Pub Date : 2023-08-28DOI: 10.1149/ma2023-01362118mtgabs
Christopher P. Rhodes, Jose Fernando Godinez Salomon, Michael E. Urena
Proton exchange membrane unitized regenerative fuel cells (PEM-URFCs) can generate storable fuel (hydrogen) and oxidant (oxygen) which can then be used to produce power from the same cell. Combining electrolysis and fuel cell modes within the same cell allows PEM-URFCs to have the potential for lower mass, volume, and cost compared with discrete fuel cell and electrolyzer systems. The bifunctional oxygen catalyst layer (BOCL) catalyzes the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR) at the same electrode, and there are wide potential differences and opposing mass transport phenomena involved within the BOCL when operating in electrolyzer or fuel cell mode. The BOCL composition, structure and morphology significantly affect performance and stability of PEM-URFCs. In our prior work, we showed bimetallic nanoframes provide bifunctional oxygen electrocatalysts with significantly higher activity compared with monometallic structures, evaluated using a rotating disk electrode configuration. 1 We will present our investigation of the effects of the BOCL composition, structure and morphology on URFC membrane electrode assemblies (MEAs) prepared using ultrasonic spraying. Catalyst composition and loading were determined to influence URFC performance, and there are tradeoffs between fuel cell performance, electrolyzer performance, and catalyst cost. In addition to the effects of the active catalyst (either Pt for ORR or IrO 2 for OER), our work supports the non-catalytically active component influences MEA performance, which is in agreement with our finding of synergistic effects of Pt and IrO 2 within rotating disk electrode measurements. 1 We are also evaluating the effects of porous transport layers and different operating conditions on URFC MEA performance and durability over repeated cycling. References Godínez-Salomón, F.; Albiter, L.; Mendoza-Cruz, R.; Rhodes, C.P. Bimetallic Two-dimensional Nanoframes: High Activity Acidic Bifunctional Oxygen Reduction and Evolution Electrocatalysts. ACS Appl. Energy Mater. 2020, 3 , 2404-2421 .
{"title":"Effects of Bifunctional Oxygen Catalyst Layer Composition on Unitized Regenerative Fuel Cell Performance","authors":"Christopher P. Rhodes, Jose Fernando Godinez Salomon, Michael E. Urena","doi":"10.1149/ma2023-01362118mtgabs","DOIUrl":"https://doi.org/10.1149/ma2023-01362118mtgabs","url":null,"abstract":"Proton exchange membrane unitized regenerative fuel cells (PEM-URFCs) can generate storable fuel (hydrogen) and oxidant (oxygen) which can then be used to produce power from the same cell. Combining electrolysis and fuel cell modes within the same cell allows PEM-URFCs to have the potential for lower mass, volume, and cost compared with discrete fuel cell and electrolyzer systems. The bifunctional oxygen catalyst layer (BOCL) catalyzes the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR) at the same electrode, and there are wide potential differences and opposing mass transport phenomena involved within the BOCL when operating in electrolyzer or fuel cell mode. The BOCL composition, structure and morphology significantly affect performance and stability of PEM-URFCs. In our prior work, we showed bimetallic nanoframes provide bifunctional oxygen electrocatalysts with significantly higher activity compared with monometallic structures, evaluated using a rotating disk electrode configuration. 1 We will present our investigation of the effects of the BOCL composition, structure and morphology on URFC membrane electrode assemblies (MEAs) prepared using ultrasonic spraying. Catalyst composition and loading were determined to influence URFC performance, and there are tradeoffs between fuel cell performance, electrolyzer performance, and catalyst cost. In addition to the effects of the active catalyst (either Pt for ORR or IrO 2 for OER), our work supports the non-catalytically active component influences MEA performance, which is in agreement with our finding of synergistic effects of Pt and IrO 2 within rotating disk electrode measurements. 1 We are also evaluating the effects of porous transport layers and different operating conditions on URFC MEA performance and durability over repeated cycling. References Godínez-Salomón, F.; Albiter, L.; Mendoza-Cruz, R.; Rhodes, C.P. Bimetallic Two-dimensional Nanoframes: High Activity Acidic Bifunctional Oxygen Reduction and Evolution Electrocatalysts. ACS Appl. Energy Mater. 2020, 3 , 2404-2421 .","PeriodicalId":11461,"journal":{"name":"ECS Meeting Abstracts","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135089192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-28DOI: 10.1149/ma2023-0154322mtgabs
Fabian Rosner, Mike C Tucker, Boxun Hu, Hanna Breunig
With the shift away from fossil resources, there is a need for alternative pathways to carbon-based commodities such as ethylene. The electrochemical oxidative coupling of methane (OCM) enables the synthesis of higher hydrocarbons from simple organic molecules i.e., methane and has the potential to replace conventional ethylene production in the future. However, current solid oxide OCM cell development is still in an early stage and more comprehensive system-level analyses are needed to better understand operating conditions and economics to guide research and development. For this purpose, process models and new integration strategies for the electrochemical OCM process were developed. The integration of the electrochemical OCM unit into the plant revealed to be challenging based on current solid oxide cell designs and will be discussed as part of this presentation. The performance of the OCM plant is benchmarked against current state-of-the-art ethane steam cracker plants. In this context, key performance metrics are efficiency, direct and indirect carbon dioxide emissions, power consumption, plant cost and cost of ethylene. Of particular interest are aspects of hydrogen co-production and carbon dioxide utilization as well as the impact of carbon dioxide emission factors from the grid, which have shown to be of particular importance for electrochemical processes. Moreover, critical aspects of heat integration will be discussed including fuel pre-heating, carbon deposition and thermal cell management. The analysis will provide new insights into economic cost driving factors and the impact of cell cost, current density, overpotentials and Faraday efficiency upon the cost of ethylene. Based upon this information, performance targets will be recommended that will allow electrochemical OCM to become economically competitive in a free market environment.
{"title":"Techno-Economic Analysis of Electrochemical Refineries Using Solid Oxide Cells for Oxidative Coupling of Methane","authors":"Fabian Rosner, Mike C Tucker, Boxun Hu, Hanna Breunig","doi":"10.1149/ma2023-0154322mtgabs","DOIUrl":"https://doi.org/10.1149/ma2023-0154322mtgabs","url":null,"abstract":"With the shift away from fossil resources, there is a need for alternative pathways to carbon-based commodities such as ethylene. The electrochemical oxidative coupling of methane (OCM) enables the synthesis of higher hydrocarbons from simple organic molecules i.e., methane and has the potential to replace conventional ethylene production in the future. However, current solid oxide OCM cell development is still in an early stage and more comprehensive system-level analyses are needed to better understand operating conditions and economics to guide research and development. For this purpose, process models and new integration strategies for the electrochemical OCM process were developed. The integration of the electrochemical OCM unit into the plant revealed to be challenging based on current solid oxide cell designs and will be discussed as part of this presentation. The performance of the OCM plant is benchmarked against current state-of-the-art ethane steam cracker plants. In this context, key performance metrics are efficiency, direct and indirect carbon dioxide emissions, power consumption, plant cost and cost of ethylene. Of particular interest are aspects of hydrogen co-production and carbon dioxide utilization as well as the impact of carbon dioxide emission factors from the grid, which have shown to be of particular importance for electrochemical processes. Moreover, critical aspects of heat integration will be discussed including fuel pre-heating, carbon deposition and thermal cell management. The analysis will provide new insights into economic cost driving factors and the impact of cell cost, current density, overpotentials and Faraday efficiency upon the cost of ethylene. Based upon this information, performance targets will be recommended that will allow electrochemical OCM to become economically competitive in a free market environment.","PeriodicalId":11461,"journal":{"name":"ECS Meeting Abstracts","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135089215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-28DOI: 10.1149/ma2023-01382232mtgabs
Daniel Houghton, Pei Zhao, Yisong Han, Richard Beanland, Julie V. Macpherson, Louis Godeffroy, Viacheslav Shkirskiy, Frederic Kanoufi, Jonathan Sharman
Proton exchange membrane fuel cell (PEMFC) electrocatalysts are typically Pt or Pt alloy nanoparticles (NPs) supported on high surface area carbon black powders, the latter which contain a significant sp 2 carbon component. One of the barriers to PEMFC commercialisation is the lifetime of the catalyst-support system, which should be at least 5,000 hours for automotive applications. [1] During the start-up and shut-down of the PEMFC, the cathode is subjected to significant oxidative potentials (greater than 1 V vs RHE) which can lead to corrosion of the predominantly sp2 bonded carbon support, a key factor which can limit the lifetime of PEMFCs. [2] High quality boron doped diamond (BDD) is an sp 3 bonded network with above 1:1000 B:C ratio, which is required for metal-like electronic conductivity. BDD has many favourable properties for electrochemical experiments, most notably: higher electrochemical corrosion resistance with respect to sp 2 carbons, low background currents, and a wide aqueous solvent window. [3] In this work we first explore the electrochemical corrosion stability of BDD when undergoing electrochemical cycling in acid solutions. To achieve this BDD substrates (BDD TEM grid) suitable for both electrochemical experiments and high magnification (single atom resolution) transmission electron microscopy (TEM) experiments were produced using precision ion polishing (Gatan PIPS-II). The surface was characterised using X-ray photoelectron spectroscopy to ensure the polishing process did not significantly alter the diamond substrate. Under aggressive electrochemical potential cycling in perchloric acid and sulfuric acid solutions, both TEM morphological analysis and Electron Energy Loss Spectroscopy (EELS) thickness measurements showed no evidence of BDD corrosion. [4] The BDD-TEM substrate was then used as a platform for investigating the degradation of a PEMFC electrocatalyst (Pt NPs) under accelerated stress testing (AST) [1] conditions on an atomic level, using the corrosion free carbon support. This enables the influence of other degradation pathways [2] (such as aggregation, Ostwald Ripening & direct dissolution) to be explored in more detail, free from issues associated with corrosion of the support. Pt NPs, in the size range 1 – 4 nm, were sputter coated onto the BDD TEM grid. Identical location ex-situ TEM (IL-TEM) [5] in combination with image analysis was used to probe NP changes e.g. size, shape, position, on an individual basis before, and after, AST (Fig. 1, which contains c.a. 200 NPs for analysis). Such measurements were complemented by Inductively Coupled Plasma – Optical Emission Spectroscopy analysis for any dissolved Pt, and electrochemical cyclic voltammetry measurements of the Pt to highlight changes in electrocatalytic behaviour (hydrogen evolution reaction and oxygen reduction reaction) due to AST cycling. Figure 1 – High magnification annular dark field (ADF) identical location images of Pt NPs, a) Pt/BDD bef
质子交换膜燃料电池(PEMFC)的电催化剂通常是铂或铂合金纳米颗粒(NPs)，支撑在高表面积的炭黑粉末上，后者含有大量的sp 2碳成分。PEMFC商业化的障碍之一是催化剂-支撑系统的使用寿命，汽车应用至少需要5000小时。[1]在PEMFC的启动和关闭过程中，阴极受到明显的氧化电位(大于1 V vs RHE)，这可能导致主要的sp2键合碳载体腐蚀，这是限制PEMFC寿命的关键因素。[2]高质量的硼掺杂金刚石(BDD)是一种B:C比在1:1000以上的sp - 3键合网络，是类金属电子导电性所必需的。BDD在电化学实验中具有许多有利的特性，最显著的是:相对于sp 2碳具有更高的电化学耐腐蚀性，低背景电流和宽的水溶液窗口。[3]在这项工作中，我们首先探索了BDD在酸性溶液中进行电化学循环时的电化学腐蚀稳定性。为了实现这一BDD衬底(BDD TEM栅格)适合电化学实验和高放大(单原子分辨率)透射电子显微镜(TEM)实验采用精密离子抛光(Gatan PIPS-II)。使用x射线光电子能谱对表面进行表征，以确保抛光过程不会显著改变金刚石衬底。在高氯酸和硫酸溶液中剧烈的电化学电位循环下，TEM形态分析和EELS厚度测量均未发现BDD腐蚀的证据。[4]然后，BDD-TEM衬底作为一个平台，在原子水平上研究了PEMFC电催化剂(Pt NPs)在加速应力测试(AST)[1]条件下的降解，使用无腐蚀碳载体。这使得其他降解途径[2](如聚集，奥斯特瓦尔德成熟&直接溶解)将更详细地探讨，不受与支架腐蚀有关的问题。将尺寸范围为1 ~ 4nm的铂纳米粒子溅射涂覆在BDD TEM网格上。同一位置非原位透射电镜(IL-TEM)[5]结合图像分析，以个体为基础，在AST前后探测NP的变化，如大小、形状、位置(图1，其中包含约200个NP用于分析)。这些测量还通过电感耦合等离子体-光学发射光谱分析对任何溶解的Pt进行了补充，并通过电化学循环伏安法对Pt进行了测量，以突出AST循环引起的电催化行为(析氢反应和氧还原反应)的变化。图1 -高倍环形暗场(ADF) Pt NPs的相同位置图像，a) AST前的Pt/BDD, b) AST后的Pt NPs, c) 1000周期AST在0.8 ~ 1.4 V vs Ag|AgCl (1.6 ~ 1.6 V vs RHE)下的循环伏安图。参考资料:美国能源部;多年研究、开发和示范计划;2016;3.4燃料电池。Mayrhofer K.J.J.;et al。[j];2014;5;44 - 67。麦克弗森,J.V.;理论物理。化学。化学。理论物理。2015年,17个;2935-2949侯赛因，H.E.M.;木头。g;霍顿。d;沃克,m;汉族,y;赵,p;Beanland r;麦克弗森,J.V.;ACS量。科学。非盟;2022;2;5;439-448 Feliu, J.M.;Abruna收听距离;j。化学。Soc。;2015;137;47岁;图1
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Pub Date : 2023-08-28DOI: 10.1149/ma2023-01492563mtgabs
Gioele Pagot, Federico Brombin, Keti Vezzu, Enrico Negro, Vito Di Noto
The large-scale rollout of electric vehicles, smart grids and portable electronics is expected to require an amount of energy storage devices that the Li-ion technology alone will not be able to satisfy. In this concern, a quest for novel electrochemical energy storage technologies has started [1]. Sodium secondary batteries appear to be a good choice due to: (i) the high availability of raw materials; (ii) the low cost of sodium; (iii) the low sodium standard reduction potential; and (iv) the similarity between the chemistries of sodium and lithium, which facilitates the transition between the two technologies. Up to date, the best-performing electrolytes for the reversible deposition of sodium are based on organic solvents, which suffer from safety concerns and a poor stability towards sodium metal. Thus, research activities in this field are devoted to the development of safe and stable solid state electrolytes able to efficiently transport Na + ions. Inspired by the pioneering work done by Di Noto and co-workers [2-4], herein we present a family of hybrid inorganic-organic polymer electrolytes (HIOPEs) for advanced solid state sodium secondary batteries. The initial HIOPE is obtained by means of a reaction between zirconium ethoxide and polyethylene glycol (PEG400). The resulting material is doped with sodium perchlorate as source of Na + ions. In this system a 3D network is obtained, where inorganic zirconium metal nodes are interconnected by means of organic PEO chains. The latter ensure flexibility to the overall structure. Na + ions are coordinated by and exchanged between the oxygen atoms of the ethereal functionalities of PEO chains. In addition, to guarantee a good structural stability, positively charged Zr nodes partially coordinate perchlorate anions, thus raising the sodium transference number. After doping with the poly(ethylene glycol) dimethyl ether (PEGDME250) plasticizer, a room temperature conductivity higher than 10 -4 S cm -1 is demonstrated. An advanced study of the thermal and structural properties of the proposed materials is presented, with a particular focus on the interactions established between the different chemical species and complexes composing the HIOPEs. The conduction mechanism is elucidated starting from the results obtained in a wide range of temperatures from broadband electrical spectroscopy studies. Taking all together, this study offers insights on the application of non-traditional solid state electrochemical functional components as replacements for conventional solvents in the emerging field of sodium secondary batteries. Acknowledgments The project “Interplay between structure, properties, relaxations and conductivity mechanism in new electrolytes for secondary Magnesium batteries” (Grant Agreement W911NF-21-1-0347-(78622-CH-INT)) of the U.S. Army Research Office. The project “ACHILLES” (prot. BIRD219831) of the University of Padua. The project “VIDICAT” (Grant Agreement 829145) of the FET-Open call
电动汽车、智能电网和便携式电子产品的大规模推广预计需要大量的能量存储设备，仅靠锂离子技术是无法满足的。在这方面，对新型电化学储能技术的探索已经开始[1]。钠二次电池似乎是一个很好的选择，因为:(1)原材料的高可用性;(二)钠的成本低;(iii)低钠标准还原电位;(iv)钠和锂的化学性质相似，这有利于两种技术之间的过渡。迄今为止，用于钠可逆沉积的性能最好的电解质是基于有机溶剂的，但存在安全问题，并且对金属钠的稳定性差。因此，该领域的研究活动致力于开发安全稳定的能够有效传输Na +离子的固态电解质。受Di Noto及其同事开创性工作的启发[2-4]，我们在这里提出了一种用于先进固态钠二次电池的无机-有机聚合物混合电解质(HIOPEs)家族。初始HIOPE是通过氧化锆和聚乙二醇(PEG400)的反应得到的。所得材料掺杂高氯酸钠作为Na +离子的来源。在该系统中获得了一个三维网络，其中无机锆金属节点通过有机PEO链相互连接。后者保证了整体结构的灵活性。钠离子通过PEO链的空灵官能团的氧原子进行配位和交换。此外，为了保证良好的结构稳定性，带正电的Zr节点部分配位高氯酸盐阴离子，从而提高了钠转移数。掺入聚乙二醇二甲醚(PEGDME250)增塑剂后，室温电导率高于10 -4 S cm -1。对所提出的材料的热学和结构特性进行了深入的研究，特别关注了组成HIOPEs的不同化学物质和配合物之间建立的相互作用。从宽频电谱研究在宽温度范围内得到的结果出发，阐明了导电机理。综上所述，本研究为非传统固态电化学功能组分替代传统溶剂在钠二次电池新兴领域的应用提供了见解。美国陆军研究办公室的项目“新型二次镁电池电解质的结构、性能、弛豫和电导率机制之间的相互作用”(资助协议W911NF-21-1-0347-(78622-CH-INT))。项目“阿喀琉斯”(proteus)。Padua大学的BIRD219831)。地平线2020年度fet公开征集项目“VIDICAT”(资助协议829145)。意大利MIUR的TRUST项目(协议2017MCEEY4)在“PRIN 2017”呼吁框架下资助。参考文献[1]R. Dominko, J. Bitenc, R. Berthelot, M. Gauthier, G. Pagot, V. Di Noto，， J.电源。478(2020) 229027。[2]李建军，李建军，李建军，等。学报48(2003)541-554。[3]李建军，李建军，李建军，等。(2010) 341-353。[4]陈晓明，陈晓明，陈晓明，等。学报45(2000)1211-1221。
{"title":"(Invited) Solid State Hybrid Inorganic Organic Polymer Electrolytes for Advanced Sodium Secondary Batteries","authors":"Gioele Pagot, Federico Brombin, Keti Vezzu, Enrico Negro, Vito Di Noto","doi":"10.1149/ma2023-01492563mtgabs","DOIUrl":"https://doi.org/10.1149/ma2023-01492563mtgabs","url":null,"abstract":"The large-scale rollout of electric vehicles, smart grids and portable electronics is expected to require an amount of energy storage devices that the Li-ion technology alone will not be able to satisfy. In this concern, a quest for novel electrochemical energy storage technologies has started [1]. Sodium secondary batteries appear to be a good choice due to: (i) the high availability of raw materials; (ii) the low cost of sodium; (iii) the low sodium standard reduction potential; and (iv) the similarity between the chemistries of sodium and lithium, which facilitates the transition between the two technologies. Up to date, the best-performing electrolytes for the reversible deposition of sodium are based on organic solvents, which suffer from safety concerns and a poor stability towards sodium metal. Thus, research activities in this field are devoted to the development of safe and stable solid state electrolytes able to efficiently transport Na + ions. Inspired by the pioneering work done by Di Noto and co-workers [2-4], herein we present a family of hybrid inorganic-organic polymer electrolytes (HIOPEs) for advanced solid state sodium secondary batteries. The initial HIOPE is obtained by means of a reaction between zirconium ethoxide and polyethylene glycol (PEG400). The resulting material is doped with sodium perchlorate as source of Na + ions. In this system a 3D network is obtained, where inorganic zirconium metal nodes are interconnected by means of organic PEO chains. The latter ensure flexibility to the overall structure. Na + ions are coordinated by and exchanged between the oxygen atoms of the ethereal functionalities of PEO chains. In addition, to guarantee a good structural stability, positively charged Zr nodes partially coordinate perchlorate anions, thus raising the sodium transference number. After doping with the poly(ethylene glycol) dimethyl ether (PEGDME250) plasticizer, a room temperature conductivity higher than 10 -4 S cm -1 is demonstrated. An advanced study of the thermal and structural properties of the proposed materials is presented, with a particular focus on the interactions established between the different chemical species and complexes composing the HIOPEs. The conduction mechanism is elucidated starting from the results obtained in a wide range of temperatures from broadband electrical spectroscopy studies. Taking all together, this study offers insights on the application of non-traditional solid state electrochemical functional components as replacements for conventional solvents in the emerging field of sodium secondary batteries. Acknowledgments The project “Interplay between structure, properties, relaxations and conductivity mechanism in new electrolytes for secondary Magnesium batteries” (Grant Agreement W911NF-21-1-0347-(78622-CH-INT)) of the U.S. Army Research Office. The project “ACHILLES” (prot. BIRD219831) of the University of Padua. The project “VIDICAT” (Grant Agreement 829145) of the FET-Open call","PeriodicalId":11461,"journal":{"name":"ECS Meeting Abstracts","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135089242","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-28DOI: 10.1149/ma2023-01492558mtgabs
Michael Philip Nitzsche, Lev Bromberg, T. Alan Hatton
Molten alkali metal borates have recently shown promise as high-temperature sorbents for capture of CO 2 and acid gases. These molten salt sorbents enable realization of thermodynamic enhancements offered by conventional solid high temperature sorbents while resolving practical challenges such as morphological degradation. Prior studies have focused on regeneration of alkali borates through steam sweeping and thermal cycling. In this work, we demonstrate that mixed sodium-lithium borate salts as CO 2 sorbents can also be regenerated electrochemically, producing valuable multiwalled carbon nanotubes (MWCNT) via electroreduction of captured CO 2 . Effects of cathode materials and operating conditions in CO 2 electroreduction in molten sodium-lithium borate are quantified. By varying relative starting compositions of alkali borates and alkali carbonates, an optimal composition of borates and carbonates is determined, achieving high coulombic efficiencies and significantly higher CO 2 uptake capacities than traditionally employed carbonate salts used for conversion of CO 2 into CNTs in the desirable 550-650°C range.
{"title":"Capture and Electrochemical Conversion of CO<sub>2</sub> into Carbon Nanotubes Using Molten Alkali Metal Borates","authors":"Michael Philip Nitzsche, Lev Bromberg, T. Alan Hatton","doi":"10.1149/ma2023-01492558mtgabs","DOIUrl":"https://doi.org/10.1149/ma2023-01492558mtgabs","url":null,"abstract":"Molten alkali metal borates have recently shown promise as high-temperature sorbents for capture of CO 2 and acid gases. These molten salt sorbents enable realization of thermodynamic enhancements offered by conventional solid high temperature sorbents while resolving practical challenges such as morphological degradation. Prior studies have focused on regeneration of alkali borates through steam sweeping and thermal cycling. In this work, we demonstrate that mixed sodium-lithium borate salts as CO 2 sorbents can also be regenerated electrochemically, producing valuable multiwalled carbon nanotubes (MWCNT) via electroreduction of captured CO 2 . Effects of cathode materials and operating conditions in CO 2 electroreduction in molten sodium-lithium borate are quantified. By varying relative starting compositions of alkali borates and alkali carbonates, an optimal composition of borates and carbonates is determined, achieving high coulombic efficiencies and significantly higher CO 2 uptake capacities than traditionally employed carbonate salts used for conversion of CO 2 into CNTs in the desirable 550-650°C range.","PeriodicalId":11461,"journal":{"name":"ECS Meeting Abstracts","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135089250","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
There is a growing interest in developing ultrasensitive biological sensors that can be used for rapid testing at the point-of-need. 1 A major hurdle in developing such sensors for detecting pathogens such as bacteria is that they require target enrichment or amplification to deliver the required limit-of-detection. 2 Among signal transduction strategies, photoelectrochemical (PEC) signal readout, built on the use of light for enhancing electrochemical reactions, is emerging as an ultrasensitive signal transduction mechanism. 3 However, the existing PEC platforms fail to deliver single step testing due to the existence of multiple manual steps, including the addition of biological materials labelled with inorganic photoactive nanoparticles, for signal transduction. 3 RNA-cleaving DNAzymes (RCDs), a class of synthetic nucleic acids, have been selected for precisely identifying specific bacterial species without the need for sample processing. 4 RCDs are molecular switches that cleave a segment of themselves in response to a particular bacterial target, combining biological recognition with signal transduction. 4 We developed photoactive RCDs by tagging them with TiO 2 nanomaterials for combining these molecular switches with PEC signal readout. We designed these molecular switches to make and then break semiconductive heterostructures in response to bacterial targets. These photoactive RCDs were the foundational basis for the design novel and highly sensitive PEC bacterial sensor. We developed two photoactive materials for use in the PEC bacterial assay: TiO 2 nanorod clusters (rutile) that form high surface area photoelectrodes and sub-nanometer sized TiO 2 -nanoparticles (anatase) that link to RCDs to create photoactive reporter probes. Combining TiO 2 -assemblies and TiO 2 -nanoparticles gives rise to a semiconductor heterostructure that massively improves the photoexcitation efficiency of the combined material system and improves photocurrent generation. Our PEC bacterial sensor makes use of this phenomenon for bacterial detection by utilizing photoactive RCDs to modulate photocurrent by breaking and then rebuilding the TiO 2 heterostructures, as a signaling mechanism. The assay consists of a release electrode – modified with photoactive RCDs and a capture electrode – modified with single-stranded DNA probes. Upon target interaction, RCDs release photoactive reporters which are captured by the probes, decreasing the release electrode signal while raising the capture electrode signal. The resulting biosensor can detect E. coli bacterial contamination with high specificity and has achieved a very low limit of detection of 21 CFU/mL in buffer and 18 CFU/mL in lake water samples. These results have set a new record for amplification-free detection of bacteria, that does not rely on target enrichment, reagent addition, or sample processing. This presents a new tool for rapid and in-field water testing. References Nat. Microbiol. , 1 , 16089 (2016).
人们对开发超灵敏的生物传感器越来越感兴趣，这种传感器可以用于在需要的地方进行快速测试。开发用于检测病原体(如细菌)的此类传感器的一个主要障碍是，它们需要对目标进行富集或扩增，以提供所需的检测限。在信号转导策略中，光电化学(PEC)信号读出是一种超灵敏的信号转导机制，它建立在利用光来增强电化学反应的基础上。然而，由于存在多个手动步骤，包括添加标记有无机光活性纳米颗粒的生物材料，用于信号转导，现有的PEC平台无法提供单步测试。rna - cleaved DNAzymes (rcd)是一类合成核酸，已被用于精确识别特定的细菌种类，而无需样品处理。rcd是一种分子开关，它对特定的细菌靶标做出反应，将生物识别与信号转导结合起来，切割自己的一段。我们通过用二氧化钛纳米材料标记它们来开发光活性rcd，并将这些分子开关与PEC信号读出相结合。我们设计了这些分子开关来制造和破坏半导体异质结构，以响应细菌目标。这些光敏rcd是设计新型高灵敏度PEC细菌传感器的基础。我们开发了两种用于PEC细菌检测的光活性材料:形成高表面积光电极的tio2纳米棒团簇(金红石)和亚纳米尺寸的tio2纳米颗粒(锐钛矿)，它们与rcd连接以创建光活性报告探针。结合tio2 -组件和tio2 -纳米颗粒产生半导体异质结构，大大提高了组合材料体系的光激发效率，并改善了光电流的产生。我们的PEC细菌传感器利用这种现象进行细菌检测，利用光活性rcd通过破坏然后重建tio2异质结构来调制光电流，作为信号机制。该分析包括一个用光活性rcd修饰的释放电极和一个用单链DNA探针修饰的捕获电极。当靶相互作用时，RCDs释放被探针捕获的光活性报告蛋白，从而降低释放电极信号，同时提高捕获电极信号。该传感器检测大肠杆菌污染的特异性高，在缓冲液中的检测限为21 CFU/mL，在湖泊水样中的检测限为18 CFU/mL。这些结果为细菌的无扩增检测创造了新的记录，不依赖于目标富集，试剂添加或样品处理。这是一种快速现场水质检测的新工具。参考文献奈特。微生物。中文信息学报，11,16089(2016)。L. Castillo-Henríquez等，传感器，20,6926(2020)。A.凯旋，S.萨哈，R.潘迪，T. F.迪达尔和L.索莱马尼，前线。化学。中文信息学报，7,617(2019)。I. Cozma, E. M. McConnell, J. D. Brennan和Y. Li, Biosens。Bioelectron。生物医学工程学报，177,112972(2021)。
{"title":"Integration of Photoelectrochemical Signal Transduction with RNA-Cleaving Dnazymes for Culture-Free Detection of Bacteria","authors":"Sadman Sakib, Zijie Zhang, Enas Osman, Farhaan Kanji, Fatemeh Bahkshandeh, Yingfu Li, Igor Zhitomirsky, Leyla Soleymani","doi":"10.1149/ma2023-01532635mtgabs","DOIUrl":"https://doi.org/10.1149/ma2023-01532635mtgabs","url":null,"abstract":"There is a growing interest in developing ultrasensitive biological sensors that can be used for rapid testing at the point-of-need. 1 A major hurdle in developing such sensors for detecting pathogens such as bacteria is that they require target enrichment or amplification to deliver the required limit-of-detection. 2 Among signal transduction strategies, photoelectrochemical (PEC) signal readout, built on the use of light for enhancing electrochemical reactions, is emerging as an ultrasensitive signal transduction mechanism. 3 However, the existing PEC platforms fail to deliver single step testing due to the existence of multiple manual steps, including the addition of biological materials labelled with inorganic photoactive nanoparticles, for signal transduction. 3 RNA-cleaving DNAzymes (RCDs), a class of synthetic nucleic acids, have been selected for precisely identifying specific bacterial species without the need for sample processing. 4 RCDs are molecular switches that cleave a segment of themselves in response to a particular bacterial target, combining biological recognition with signal transduction. 4 We developed photoactive RCDs by tagging them with TiO 2 nanomaterials for combining these molecular switches with PEC signal readout. We designed these molecular switches to make and then break semiconductive heterostructures in response to bacterial targets. These photoactive RCDs were the foundational basis for the design novel and highly sensitive PEC bacterial sensor. We developed two photoactive materials for use in the PEC bacterial assay: TiO 2 nanorod clusters (rutile) that form high surface area photoelectrodes and sub-nanometer sized TiO 2 -nanoparticles (anatase) that link to RCDs to create photoactive reporter probes. Combining TiO 2 -assemblies and TiO 2 -nanoparticles gives rise to a semiconductor heterostructure that massively improves the photoexcitation efficiency of the combined material system and improves photocurrent generation. Our PEC bacterial sensor makes use of this phenomenon for bacterial detection by utilizing photoactive RCDs to modulate photocurrent by breaking and then rebuilding the TiO 2 heterostructures, as a signaling mechanism. The assay consists of a release electrode – modified with photoactive RCDs and a capture electrode – modified with single-stranded DNA probes. Upon target interaction, RCDs release photoactive reporters which are captured by the probes, decreasing the release electrode signal while raising the capture electrode signal. The resulting biosensor can detect E. coli bacterial contamination with high specificity and has achieved a very low limit of detection of 21 CFU/mL in buffer and 18 CFU/mL in lake water samples. These results have set a new record for amplification-free detection of bacteria, that does not rely on target enrichment, reagent addition, or sample processing. This presents a new tool for rapid and in-field water testing. References Nat. Microbiol. , 1 , 16089 (2016).","PeriodicalId":11461,"journal":{"name":"ECS Meeting Abstracts","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135089252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-28DOI: 10.1149/ma2023-01452470mtgabs
Xinhao Li, Wing-Chi Ashley Lam, In Won Yeu, Abhiroop Mishra, Joaquin Rodriguez Lopez, Alexander Urban
Although LiNiO 2 (LNO) is chemically very similar to LiCoO 2 (LCO), LNO and related Co-free Ni-rich cathodes suffer from continuing surface degradation via oxygen gas release during electrochemical cycling that leads to the formation of surface phases with high impedance. While the surface degradation of LNO and related cathode compositions have been characterized experimentally on a phenomenological level, an understanding of the surface reconstructions that form on the atomic scale and the intrinsic surface instability of LNO compared with other related cathode compositions is still lacking. To shed light on surface reactivity, we developed a thermodynamic methodology for the prediction of voltage and temperature-dependent surface electrode reconstructions [1] and a computational framework to automate the time-consuming enumeration of surface reconstructions, the construction of symmetric surface-slab models, and the analysis of surface phase diagrams [2]. By applying first-principles atomistic modeling, we determined the self-reduction mechanism of LNO and compared the stable surface reconstructions with those of LCO. To further assess the surface stability of more complicated NMC/NCA cathodes with the help of our own generated LNO and LCO databases, we developed a supervised machine learning (ML) model to train on geometrical and electronic fingerprints from surface and bulk models, respectively. Our results provide insight into the initial stages of surface degradation in Ni-rich cathodes and lay the foundation for the computational design of stable cathode materials against oxygen release. Li, X.; Wang, Q.; Guo, H.; Artrith, N.; Urban, A. ACS Appl. Energy Mater. 2022, 5 (5), 5730–5741. Li, X.; Qu, J.; Yeu, I.; Li, Z.; Rodríguez-López, J.; Urban, A., in preparation , 2023
{"title":"Predicting Oxygen Release and Surface Reconstructions in Li-Ion Battery Cathodes Via Automated Construction of Computational Surface Phase Diagrams and Machine Learning","authors":"Xinhao Li, Wing-Chi Ashley Lam, In Won Yeu, Abhiroop Mishra, Joaquin Rodriguez Lopez, Alexander Urban","doi":"10.1149/ma2023-01452470mtgabs","DOIUrl":"https://doi.org/10.1149/ma2023-01452470mtgabs","url":null,"abstract":"Although LiNiO 2 (LNO) is chemically very similar to LiCoO 2 (LCO), LNO and related Co-free Ni-rich cathodes suffer from continuing surface degradation via oxygen gas release during electrochemical cycling that leads to the formation of surface phases with high impedance. While the surface degradation of LNO and related cathode compositions have been characterized experimentally on a phenomenological level, an understanding of the surface reconstructions that form on the atomic scale and the intrinsic surface instability of LNO compared with other related cathode compositions is still lacking. To shed light on surface reactivity, we developed a thermodynamic methodology for the prediction of voltage and temperature-dependent surface electrode reconstructions [1] and a computational framework to automate the time-consuming enumeration of surface reconstructions, the construction of symmetric surface-slab models, and the analysis of surface phase diagrams [2]. By applying first-principles atomistic modeling, we determined the self-reduction mechanism of LNO and compared the stable surface reconstructions with those of LCO. To further assess the surface stability of more complicated NMC/NCA cathodes with the help of our own generated LNO and LCO databases, we developed a supervised machine learning (ML) model to train on geometrical and electronic fingerprints from surface and bulk models, respectively. Our results provide insight into the initial stages of surface degradation in Ni-rich cathodes and lay the foundation for the computational design of stable cathode materials against oxygen release. Li, X.; Wang, Q.; Guo, H.; Artrith, N.; Urban, A. ACS Appl. Energy Mater. 2022, 5 (5), 5730–5741. Li, X.; Qu, J.; Yeu, I.; Li, Z.; Rodríguez-López, J.; Urban, A., in preparation , 2023","PeriodicalId":11461,"journal":{"name":"ECS Meeting Abstracts","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135089256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-28DOI: 10.1149/ma2023-0154187mtgabs
Christian Rose, Luca Mastropasqua, Jack Brouwer
Temperature, current density, steam utilization variability, and local steam starvation or excess may cause diverse degradation processes to occur in solid oxide electrolysis cells. Typical degradation mechanisms for SOEC with nickel-based fuel electrode materials include nickel migration/evaporation and agglomeration, which may lead to reduced active sites at the triple-phase boundary. However, the phenomenological cause of such degradation mechanisms is still actively debated, making the selection of a durable fuel electrode material challenging. It is desirable to understand the process by which these phenomena occur not only to minimize it, but to intentionally induce it to develop accelerated stress test protocols for cell lifetime prognostics. The degradation of solid oxide electrolyzers has been reported to be accelerated by certain stressful operating conditions. Brisse and Mocotuguy conducted a review of the degradation mechanisms of solid oxide button cells; they reported that high steam partial pressures can lead to the formation of nickel hydroxide at the cathode, which then diffuse to the surface of YSZ 1 . Sun et al. hypothesize that this is the main mechanism for nickel migration, due to the positive oxidation state of nickel and the direction of the electric potential 2 . Changes in the surface morphology of the fuel electrode due to redox cycle-induced degradation has been reported, showing the dynamics of nickel migration and agglomeration under these conditions 3 . Redox cycling was found to be a destructive test protocol; efforts are currently being made by the group of Daria Vladikova to prevent fracturing of the electrodes and electrolyte during such stressful testing 4 . Königshofer et al. have reported through multiple investigations that protocols inducing operation at high steam conversion rates (>90%) and large current densities (0.8 A/cm 2 ) have been effective at reproducing long-term SOEC voltage degradation 5,6 . The objective of this research is to establish a protocol that will help determine the causes that trigger Ni migration or evaporation, and that will mimic the electrode degradation mechanism to standardize the procedure for comparing the long-term performance of solid oxide electrolysis cells. Symmetric button cells of various fuel electrode chemistries with a diameter of 20 mm (active area 1.23 cm 2 ) are tested under symmetric atmospheres with steam/H 2 blends. The following two accelerated stress tests (AST) protocols are employed: cycling of steam partial pressure and cycling of current density. In the former, the steam molar fraction is varied from 75% to 95% in a 20-minute cycle for at least 400 cycles (i.e., 1,176 h). In the latter protocol, current density is controlled using a galvanodynamic 10-minute long cyclic ramp profile between 0.8 A/cm 2 and 1.5 A/cm 2 at a constant steam molar fraction between 75-95% for at least 800 cycles (i.e., 1,176 h). For all tests, the cells are operated at a con
温度、电流密度、蒸汽利用率可变性和局部蒸汽缺乏或过剩可能导致固体氧化物电解池中发生不同的降解过程。镍基燃料电极材料对SOEC的典型降解机制包括镍的迁移/蒸发和团聚，这可能导致三相边界活性位点的减少。然而，这种降解机制的现象学原因仍然存在争议，这使得选择耐用的燃料电极材料具有挑战性。我们希望了解这些现象发生的过程，不仅是为了尽量减少它，而且是为了有意地诱导它来开发用于细胞寿命预后的加速压力测试方案。据报道，固体氧化物电解槽的降解在一定的高压操作条件下会加速。Brisse和Mocotuguy对固体氧化物纽扣电池的降解机制进行了综述;他们报告说，高蒸汽分压会导致阴极形成氢氧化镍，然后扩散到ysz1的表面。Sun等人假设这是镍迁移的主要机制，由于镍的正氧化态和电势2的方向。据报道，由于氧化还原循环引起的降解，燃料电极表面形貌发生了变化，显示了在这些条件下镍迁移和团聚的动力学。发现氧化还原循环是一种破坏性的试验方案;达里亚·弗拉迪科娃(Daria Vladikova)小组目前正在努力防止在这种压力测试中电极和电解质破裂。Königshofer等人通过多次调查报道，在高蒸汽转化率(>90%)和大电流密度(0.8 A/ cm2)下诱导操作的方案有效地再现了长期的SOEC电压退化5,6。本研究的目的是建立一个方案，以帮助确定触发Ni迁移或蒸发的原因，并将模拟电极降解机制，以标准化比较固体氧化物电解电池长期性能的程序。在蒸汽/ h2混合物的对称气氛下，对直径为20mm(活性面积1.23 cm 2)的各种燃料电极化学的对称纽扣电池进行了测试。采用了蒸汽分压循环和电流密度循环两种加速应力测试(AST)协议。在前,蒸汽摩尔分数从75%变化到95% 20分钟周期至少400周期(例如,1176 h)。在后一种协议,电流密度控制使用galvanodynamic 10分钟长循环斜坡剖面/厘米2 0.8和1.5之间以恒定的蒸汽/厘米2摩尔分数在75 - 95%之间至少800个周期(即1176 h)。对于所有的测试,细胞在一个常数炉温700°C到850°C。在AST过程中，用电化学阻抗谱(EIS)和每隔12 h的极化曲线来表达各种细胞的性能特征，用x射线衍射(XRD)和荧光(XRF)分析细胞在生命初期和死亡后的状态，以识别运行过程中发生的相变。扫描电子显微镜-能量色散光谱(SEM-EDS)和辉光放电光谱(GD)用于识别和绘制阴极表面和横截面上的镍浓度。初步结果表明，在恒定高蒸汽条件下，高频电阻可提高近500% (>90%)在Ni-YSZ|YSZ|Ni-YSZ电池中工作200小时。张建军，张建军，张建军，等。氢能与氢能的关系[J] .能源工程学报，2003,19(3):557 - 557(2013)。Sun, T. L. Skafte和S. H. Jensen，燃料电池(2021)。杨士林等，合金材料学报，1999,16(6):444 - 444。D. Vladikova等人，能源(巴塞尔)，15(2022)。B. Königshofer et al.， J Power Sources, 523(2022)。B. Königshofer et al.， J Power Sources, 497(2021)。
{"title":"Accelerated Stress Testing of Solid Oxide Electrolysis Cells in a Symmetric Steam-Rich Atmosphere","authors":"Christian Rose, Luca Mastropasqua, Jack Brouwer","doi":"10.1149/ma2023-0154187mtgabs","DOIUrl":"https://doi.org/10.1149/ma2023-0154187mtgabs","url":null,"abstract":"Temperature, current density, steam utilization variability, and local steam starvation or excess may cause diverse degradation processes to occur in solid oxide electrolysis cells. Typical degradation mechanisms for SOEC with nickel-based fuel electrode materials include nickel migration/evaporation and agglomeration, which may lead to reduced active sites at the triple-phase boundary. However, the phenomenological cause of such degradation mechanisms is still actively debated, making the selection of a durable fuel electrode material challenging. It is desirable to understand the process by which these phenomena occur not only to minimize it, but to intentionally induce it to develop accelerated stress test protocols for cell lifetime prognostics. The degradation of solid oxide electrolyzers has been reported to be accelerated by certain stressful operating conditions. Brisse and Mocotuguy conducted a review of the degradation mechanisms of solid oxide button cells; they reported that high steam partial pressures can lead to the formation of nickel hydroxide at the cathode, which then diffuse to the surface of YSZ 1 . Sun et al. hypothesize that this is the main mechanism for nickel migration, due to the positive oxidation state of nickel and the direction of the electric potential 2 . Changes in the surface morphology of the fuel electrode due to redox cycle-induced degradation has been reported, showing the dynamics of nickel migration and agglomeration under these conditions 3 . Redox cycling was found to be a destructive test protocol; efforts are currently being made by the group of Daria Vladikova to prevent fracturing of the electrodes and electrolyte during such stressful testing 4 . Königshofer et al. have reported through multiple investigations that protocols inducing operation at high steam conversion rates (>90%) and large current densities (0.8 A/cm 2 ) have been effective at reproducing long-term SOEC voltage degradation 5,6 . The objective of this research is to establish a protocol that will help determine the causes that trigger Ni migration or evaporation, and that will mimic the electrode degradation mechanism to standardize the procedure for comparing the long-term performance of solid oxide electrolysis cells. Symmetric button cells of various fuel electrode chemistries with a diameter of 20 mm (active area 1.23 cm 2 ) are tested under symmetric atmospheres with steam/H 2 blends. The following two accelerated stress tests (AST) protocols are employed: cycling of steam partial pressure and cycling of current density. In the former, the steam molar fraction is varied from 75% to 95% in a 20-minute cycle for at least 400 cycles (i.e., 1,176 h). In the latter protocol, current density is controlled using a galvanodynamic 10-minute long cyclic ramp profile between 0.8 A/cm 2 and 1.5 A/cm 2 at a constant steam molar fraction between 75-95% for at least 800 cycles (i.e., 1,176 h). For all tests, the cells are operated at a con","PeriodicalId":11461,"journal":{"name":"ECS Meeting Abstracts","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135089268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-28DOI: 10.1149/ma2023-01362023mtgabs
Marko Malinovic, Paul Paciok, Ezra Shanli Koh, Moritz Geuß, Jisik Choi, Philipp Pfeifer, Jan Philipp Hofmann, Daniel Göhl, Marc Heggen, Serhiy Cherevko, Marc Ledendecker
Polymer electrolyte membrane (PEM) electrolysis is considered to play a vital role in the sustainable energy transition. The efficient generation of hydrogen is largely influenced by the slow rate of the anodic oxygen evolution reaction (OER). Iridium oxide represents one of the most promising catalysts for the electrochemical oxidation of water in an acidic environment. Under harsh operating conditions at the anode, iridium oxide is found to be among the most dissolution-resistant catalysts while offering acceptable OER activity. However, iridium’s limited availability dictates high costs centralizing the research in direction of reducing noble metal content while maintaining favorable electrochemical properties. [1] Designing nanostructured catalyst with an increased surface-to-volume ratio improves the application-oriented mass-specific activity. [2] Hydrous iridium oxide is known for superior OER activity, but for a successful application, drastic dissolution of the catalyst must be addressed by stabilization. This can be achieved by heat treatment to temperatures ≥400ºC with the formation of crystalline order. However, managing to avoid agglomeration of nanoparticles at high temperatures is not trivial, thus, temperature studies on electrochemical stability and activity on similar particle sizes are missing. [3] . Here, we demonstrate how nanoparticles below 10 nm can be obtained at high preparation temperatures up to 800 °C with unprecedented control over particle size and morphology. A detailed understanding of the structural evolution during heating was obtained by in-situ scanning transmission electron microscopy ( in-situ STEM) with locally resolved nanoparticles, high spatial resolution, and chemical specificity. Additionally, changes in surface properties at different temperatures were tracked ex-situ by X-ray photoelectron spectroscopy (XPS), the crystal structure was investigated by X-ray diffraction analysis (XRD), size and morphology were characterized by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). The OER activities of synthesized iridium oxide nanoparticles were measured in half-cell measurements at forced convection. The stability was carefully studied by operando flow cell measurements that were coupled to online inductively coupled plasma mass spectrometry. [4] The iridium oxide catalyst calcined at the lowest temperature resulted in outstanding mass-specific activity outperforming the reference iridium oxide catalyst by a factor of 40. By gradual increase in calcination temperatures up to 800 °C, we observe improvement in the durability of the synthesized catalysts, being comparable to the reference catalyst, yet still with notable improvement in catalytic activity. This is the first report to synthesize iridium oxide nanoparticles at high temperatures with preserved size and morphology not exceeding 10 nm and allows for the determination of activity and durability of similarly sized
{"title":"Size-Controlled Synthesis of IrO<sub>2 </sub>nanoparticles at High Temperatures for the Oxygen Evolution Reaction","authors":"Marko Malinovic, Paul Paciok, Ezra Shanli Koh, Moritz Geuß, Jisik Choi, Philipp Pfeifer, Jan Philipp Hofmann, Daniel Göhl, Marc Heggen, Serhiy Cherevko, Marc Ledendecker","doi":"10.1149/ma2023-01362023mtgabs","DOIUrl":"https://doi.org/10.1149/ma2023-01362023mtgabs","url":null,"abstract":"Polymer electrolyte membrane (PEM) electrolysis is considered to play a vital role in the sustainable energy transition. The efficient generation of hydrogen is largely influenced by the slow rate of the anodic oxygen evolution reaction (OER). Iridium oxide represents one of the most promising catalysts for the electrochemical oxidation of water in an acidic environment. Under harsh operating conditions at the anode, iridium oxide is found to be among the most dissolution-resistant catalysts while offering acceptable OER activity. However, iridium’s limited availability dictates high costs centralizing the research in direction of reducing noble metal content while maintaining favorable electrochemical properties. [1] Designing nanostructured catalyst with an increased surface-to-volume ratio improves the application-oriented mass-specific activity. [2] Hydrous iridium oxide is known for superior OER activity, but for a successful application, drastic dissolution of the catalyst must be addressed by stabilization. This can be achieved by heat treatment to temperatures ≥400ºC with the formation of crystalline order. However, managing to avoid agglomeration of nanoparticles at high temperatures is not trivial, thus, temperature studies on electrochemical stability and activity on similar particle sizes are missing. [3] . Here, we demonstrate how nanoparticles below 10 nm can be obtained at high preparation temperatures up to 800 °C with unprecedented control over particle size and morphology. A detailed understanding of the structural evolution during heating was obtained by in-situ scanning transmission electron microscopy ( in-situ STEM) with locally resolved nanoparticles, high spatial resolution, and chemical specificity. Additionally, changes in surface properties at different temperatures were tracked ex-situ by X-ray photoelectron spectroscopy (XPS), the crystal structure was investigated by X-ray diffraction analysis (XRD), size and morphology were characterized by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). The OER activities of synthesized iridium oxide nanoparticles were measured in half-cell measurements at forced convection. The stability was carefully studied by operando flow cell measurements that were coupled to online inductively coupled plasma mass spectrometry. [4] The iridium oxide catalyst calcined at the lowest temperature resulted in outstanding mass-specific activity outperforming the reference iridium oxide catalyst by a factor of 40. By gradual increase in calcination temperatures up to 800 °C, we observe improvement in the durability of the synthesized catalysts, being comparable to the reference catalyst, yet still with notable improvement in catalytic activity. This is the first report to synthesize iridium oxide nanoparticles at high temperatures with preserved size and morphology not exceeding 10 nm and allows for the determination of activity and durability of similarly sized","PeriodicalId":11461,"journal":{"name":"ECS Meeting Abstracts","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135089300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-28DOI: 10.1149/ma2023-0154142mtgabs
Saahir Ganti-Agrawal, Dalton Cox, Scott A Barnett
Improving solid oxide cell power density will enable cheaper commercial-scale SOFCs and SOECs. In Ni-YSZ electrode-supported cells, gas diffusion through the electrode support layer can be a major limitation at high H 2 or H 2 O utilization and high temperature. Conventional methods of improving diffusion through the electrode support include increasing the support porosity and reducing the support thickness, but these can reduce the cell’s structural integrity. Freeze casting 1 and 3D printing 2 have also been explored to enhance diffusion. Here we explore cells in which the Ni-YSZ supports have macroscopic channels, produced by laser ablation, that reduce the average gas diffusion length. To test the difference in mass transport through patterned and pristine electrode supports, symmetric electrode-supported Ni-YSZ cells are patterned on one side, which enables comparison of the electrochemical performance of two otherwise identical electrodes (Figure 1a). Cells with varying pattern geometry, pore geometries, Ni/YSZ ratios, and Ni-YSZ particle sizes were created to fully understand how the support layer microstructure and macrostructure affects the cell performance. Patterned and pristine cells were tested together at three temperatures (600C, 700C, and 800C) in a 97%H 2 :3%H 2 O environment, chosen to produce a clear gas diffusion limitation in H 2 O electrolysis. j-V sweeps and electrochemical impedance spectroscopy (EIS) were carried out on each cell at each test condition, and the microstructure of patterned and control supports was characterized through SEM imaging. Upon removing the ohmic portion and fitting the j-V data to Equation 1 (see Figure 1), patterned electrodes consistently demonstrated higher limiting current density and lower mass transport losses than the control (Figure 1c-d). Three-point-bend mechanical testing revealed that the mean flexural fracture strengths of pristine cells and patterned cells are 36.0 ± 11.4 MPa and 33.0 ± 8.9 MPa respectively. Combining the equations for limiting current density with diffusion in a system with prismatic channels, we determined the ratio of the limiting current density for a patterned and pristine electrode using Equation 2 (see Figure). For the cell data shown in Figures 1c-1d, we expect an average 33% increase (with a standard deviation of 3.5%) in limiting current density based on microscopy measurements of channel and support layer thicknesses. In 1c, we see that the limiting current density of the patterned electrode is 32% higher than the pristine electrode, which matches our expectation. Furthermore, the Nyquist plot in Figure 1d demonstrates that patterned symmetric cells have similar impedance to pristine cells in the high-frequency regime with less impedance in the low-frequency regime, which is consistent with our expectations that the patterned cells have reduced mass transport losses with similar ohmic and activation losses. These j-V and EIS results suggest that macrosco
{"title":"Improving Gas Diffusion in Solid Oxide Cells Through Laser-Ablated Electrode Supports","authors":"Saahir Ganti-Agrawal, Dalton Cox, Scott A Barnett","doi":"10.1149/ma2023-0154142mtgabs","DOIUrl":"https://doi.org/10.1149/ma2023-0154142mtgabs","url":null,"abstract":"Improving solid oxide cell power density will enable cheaper commercial-scale SOFCs and SOECs. In Ni-YSZ electrode-supported cells, gas diffusion through the electrode support layer can be a major limitation at high H 2 or H 2 O utilization and high temperature. Conventional methods of improving diffusion through the electrode support include increasing the support porosity and reducing the support thickness, but these can reduce the cell’s structural integrity. Freeze casting 1 and 3D printing 2 have also been explored to enhance diffusion. Here we explore cells in which the Ni-YSZ supports have macroscopic channels, produced by laser ablation, that reduce the average gas diffusion length. To test the difference in mass transport through patterned and pristine electrode supports, symmetric electrode-supported Ni-YSZ cells are patterned on one side, which enables comparison of the electrochemical performance of two otherwise identical electrodes (Figure 1a). Cells with varying pattern geometry, pore geometries, Ni/YSZ ratios, and Ni-YSZ particle sizes were created to fully understand how the support layer microstructure and macrostructure affects the cell performance. Patterned and pristine cells were tested together at three temperatures (600C, 700C, and 800C) in a 97%H 2 :3%H 2 O environment, chosen to produce a clear gas diffusion limitation in H 2 O electrolysis. j-V sweeps and electrochemical impedance spectroscopy (EIS) were carried out on each cell at each test condition, and the microstructure of patterned and control supports was characterized through SEM imaging. Upon removing the ohmic portion and fitting the j-V data to Equation 1 (see Figure 1), patterned electrodes consistently demonstrated higher limiting current density and lower mass transport losses than the control (Figure 1c-d). Three-point-bend mechanical testing revealed that the mean flexural fracture strengths of pristine cells and patterned cells are 36.0 ± 11.4 MPa and 33.0 ± 8.9 MPa respectively. Combining the equations for limiting current density with diffusion in a system with prismatic channels, we determined the ratio of the limiting current density for a patterned and pristine electrode using Equation 2 (see Figure). For the cell data shown in Figures 1c-1d, we expect an average 33% increase (with a standard deviation of 3.5%) in limiting current density based on microscopy measurements of channel and support layer thicknesses. In 1c, we see that the limiting current density of the patterned electrode is 32% higher than the pristine electrode, which matches our expectation. Furthermore, the Nyquist plot in Figure 1d demonstrates that patterned symmetric cells have similar impedance to pristine cells in the high-frequency regime with less impedance in the low-frequency regime, which is consistent with our expectations that the patterned cells have reduced mass transport losses with similar ohmic and activation losses. These j-V and EIS results suggest that macrosco","PeriodicalId":11461,"journal":{"name":"ECS Meeting Abstracts","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135089307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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