Pub Date : 2022-08-23DOI: 10.33961/jecst.2022.00458
M. Ha, Donghoon Shin, Jeawoo Jung, E. Audasso, Juhun Song, Yong-Tae Kim, Hee-Young Park, Hyun S. Park, You-Me Na, J. Jang
In this study, the electrochemical impedance characteristics of CO 2 /H 2 O co-reduction to produce CO/H 2 syngas were investigated in a low-temperature single cell. The effect of the operating conditions on the single-cell performance was evaluated at different feed concentrations and cell voltages, and the corresponding electrochemical impedance spectroscopy (EIS) data were collected and analyzed. The Nyquist plots exhibited two semicircles with separated characteristic frequencies of approximately 1 kHz and tens of Hz. The high-frequency semicircles, which depend only on the catholyte concentration, could be correlated to the charge transfer processes in competitive CO 2 reduction and hydrogen evolution reactions at the cathodes. The EIS characteristics of the CO 2 /H 2 O co-reduction single cell could be explained by the equivalent circuit sug-gested in this study. In this circuit, the cathodic mass transfer and anodic charge transfer processes are collectively represented by a parallel combination of resistance and a constant phase element to show low-frequency semicircles. Through nonlinear fitting using the equivalent circuit, the parameters for each electrochemical element, such as polarization resistances for high- and low-frequency processes, could be quantified as functions of feed concentration and cell voltage.
{"title":"Electrochemical Impedance Characteristics of a Low-Temperature Single Cell for CO2/H2O Co-Reduction to Produce Syngas (CO+H2)","authors":"M. Ha, Donghoon Shin, Jeawoo Jung, E. Audasso, Juhun Song, Yong-Tae Kim, Hee-Young Park, Hyun S. Park, You-Me Na, J. Jang","doi":"10.33961/jecst.2022.00458","DOIUrl":"https://doi.org/10.33961/jecst.2022.00458","url":null,"abstract":"In this study, the electrochemical impedance characteristics of CO 2 /H 2 O co-reduction to produce CO/H 2 syngas were investigated in a low-temperature single cell. The effect of the operating conditions on the single-cell performance was evaluated at different feed concentrations and cell voltages, and the corresponding electrochemical impedance spectroscopy (EIS) data were collected and analyzed. The Nyquist plots exhibited two semicircles with separated characteristic frequencies of approximately 1 kHz and tens of Hz. The high-frequency semicircles, which depend only on the catholyte concentration, could be correlated to the charge transfer processes in competitive CO 2 reduction and hydrogen evolution reactions at the cathodes. The EIS characteristics of the CO 2 /H 2 O co-reduction single cell could be explained by the equivalent circuit sug-gested in this study. In this circuit, the cathodic mass transfer and anodic charge transfer processes are collectively represented by a parallel combination of resistance and a constant phase element to show low-frequency semicircles. Through nonlinear fitting using the equivalent circuit, the parameters for each electrochemical element, such as polarization resistances for high- and low-frequency processes, could be quantified as functions of feed concentration and cell voltage.","PeriodicalId":15542,"journal":{"name":"Journal of electrochemical science and technology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2022-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43081553","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-08-23DOI: 10.33961/jecst.2022.00262
M. Rahman, H. Kang, Kicheon Yoo, Jae‐Joon Lee
A chemically sintered and binder-free paste of TiO 2 nanoparticles (NPs) was prepared using a binary-liquid mixture of 1-octanol and CCl 4 . The 1:1 (v/v) complex of CCl 4 and 1-octanol easily interacted chemically with the TiO 2 NPs and induced the formation of a highly viscous paste. The as-prepared binary-liquid paste ( P BL )-based TiO 2 film exhibited the complete removal of the binary-liquid and residuals with the subsequent low-temperature sintering (~150ºC) and UV-O 3 treatment. This facilitated the fabrication of TiO 2 photoanodes for flexible dye-sensitized solar cells ( f -DSSCs). For comparison pur-poses, pure 1-octanol-based TiO 2 paste ( P O ) with moderate viscosity was prepared. The P BL -based TiO 2 film exhibited strong adhesion and high mechanical stability with the conducting oxide coated glass and plastic substrates compared to the P O -based film. The corresponding low-temperature sintered P BL -based f -DSSC showed a power conversion efficiency (PCE) of 3.5%, while it was 2.0% for P O -based f -DSSC. The P BL - based low- and high-temperature (500ºC) sintered glass-based rigid DSSCs exhibited the PCE of 6.0 and 6.3%, respectively, while this value was 7.1% for a 500ºC sintered rigid DSSC based on a commercial (or conventional) paste.
{"title":"Low-Temperature Chemical Sintered TiO2 Photoanodes Based on a Binary Liquid Mixture for Flexible Dye-Sensitized Solar Cells","authors":"M. Rahman, H. Kang, Kicheon Yoo, Jae‐Joon Lee","doi":"10.33961/jecst.2022.00262","DOIUrl":"https://doi.org/10.33961/jecst.2022.00262","url":null,"abstract":"A chemically sintered and binder-free paste of TiO 2 nanoparticles (NPs) was prepared using a binary-liquid mixture of 1-octanol and CCl 4 . The 1:1 (v/v) complex of CCl 4 and 1-octanol easily interacted chemically with the TiO 2 NPs and induced the formation of a highly viscous paste. The as-prepared binary-liquid paste ( P BL )-based TiO 2 film exhibited the complete removal of the binary-liquid and residuals with the subsequent low-temperature sintering (~150ºC) and UV-O 3 treatment. This facilitated the fabrication of TiO 2 photoanodes for flexible dye-sensitized solar cells ( f -DSSCs). For comparison pur-poses, pure 1-octanol-based TiO 2 paste ( P O ) with moderate viscosity was prepared. The P BL -based TiO 2 film exhibited strong adhesion and high mechanical stability with the conducting oxide coated glass and plastic substrates compared to the P O -based film. The corresponding low-temperature sintered P BL -based f -DSSC showed a power conversion efficiency (PCE) of 3.5%, while it was 2.0% for P O -based f -DSSC. The P BL - based low- and high-temperature (500ºC) sintered glass-based rigid DSSCs exhibited the PCE of 6.0 and 6.3%, respectively, while this value was 7.1% for a 500ºC sintered rigid DSSC based on a commercial (or conventional) paste.","PeriodicalId":15542,"journal":{"name":"Journal of electrochemical science and technology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2022-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45518903","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-18DOI: 10.33961/jecst.2022.00234
B. A. Fil, Cansu Elgün, Sevim Alya Cihan, Sermin Günaslan, A. Yılmaz
In the study, Ni 2+ (nickel) removal from synthetically prepared wastewater by electrocoagulation method, which is one of the electrochemical treatment processes, was investigated and parameters such as current density, pH, mixing speed, initial Ni 2+ concentration, supporting electrolyte type and concentration were determined to determine Ni 2+ removal efficiencies effects were studied. Experiment conditions during 30 minutes of electrolysis; the current density was determined as 0.95 mA/cm 2 , the initial pH of the wastewater was 6, the mixing speed was 150 rpm, and the initial nickel concentration was 250 mg/L. The Ni 2+ removal efficiency was obtained as 75.99% under the determined experimental conditions, while the energy consumption was calculated as 3.15 kW-h/m 3 . In the experiments, it was observed that the type and concentration of the supporting electrolyte did not have a significant effect on the Ni 2+ removal efficiency. In the trials where the effect of the support electrolyte concentration was examined, the Ni 2+ removal efficiency was 75.99% in the wastewater environment without the supporting electrolyte, while the Ni 2+ removal efficiency was 81.55% when 7.5 mmol/L NaCl was used after the 30-minute reaction, and the energy consumption was 2.15 kW-h/m 3 obtained as. As a result of the studies, it was concluded that the electrocoagulation process can be applied in the treatment of wastewater containing Ni 2+ .
{"title":"Investigation of Nickel Removal from Heavy Metal Containing Industrial Wastewater by Electrocoagulation Method","authors":"B. A. Fil, Cansu Elgün, Sevim Alya Cihan, Sermin Günaslan, A. Yılmaz","doi":"10.33961/jecst.2022.00234","DOIUrl":"https://doi.org/10.33961/jecst.2022.00234","url":null,"abstract":"In the study, Ni 2+ (nickel) removal from synthetically prepared wastewater by electrocoagulation method, which is one of the electrochemical treatment processes, was investigated and parameters such as current density, pH, mixing speed, initial Ni 2+ concentration, supporting electrolyte type and concentration were determined to determine Ni 2+ removal efficiencies effects were studied. Experiment conditions during 30 minutes of electrolysis; the current density was determined as 0.95 mA/cm 2 , the initial pH of the wastewater was 6, the mixing speed was 150 rpm, and the initial nickel concentration was 250 mg/L. The Ni 2+ removal efficiency was obtained as 75.99% under the determined experimental conditions, while the energy consumption was calculated as 3.15 kW-h/m 3 . In the experiments, it was observed that the type and concentration of the supporting electrolyte did not have a significant effect on the Ni 2+ removal efficiency. In the trials where the effect of the support electrolyte concentration was examined, the Ni 2+ removal efficiency was 75.99% in the wastewater environment without the supporting electrolyte, while the Ni 2+ removal efficiency was 81.55% when 7.5 mmol/L NaCl was used after the 30-minute reaction, and the energy consumption was 2.15 kW-h/m 3 obtained as. As a result of the studies, it was concluded that the electrocoagulation process can be applied in the treatment of wastewater containing Ni 2+ .","PeriodicalId":15542,"journal":{"name":"Journal of electrochemical science and technology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2022-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48019178","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-15DOI: 10.33961/jecst.2022.00269
Xiaohua Jiang, Zhiwen Lv, Wenjie Ding, Ying Zhang, F. Lin
As one of the most hazardous and deadliest pathogens, Listeria monocytogenes (LM) posed various serious diseases to the human being, thus designing effective strategy for its detection is of great significance. In this work, by preparing Ti 3 C 2 T x MXenes nanoribbon (Ti 3 C 2 T x R) as carrier and selecting thionine (Th) acted simultaneously as signal probe and functional monomer, a LM pathogen-imprinted polymers (PIP) integrated probe electrochemical sensor was design to monitor LM for the first time, that was carried out through the electropolymerization of Th on the Ti 3 C 2 T x R/GCE surface in the exis-tence of LM. Upon eluting the templates from the LM imprinted cavities, the fabricated PIP/Ti 3 C 2 T x R/GCE sensor can rebound LM cells effectively. By recording the peak current of Th as the response signal, it can be weakened when LM cell was re-bound to the LM imprinted cavity on PIP/Ti 3 C 2 T x R/GCE, and the absolute values of peak current change increase with the increasement of LM concentrations. After optimizing three key parameters, a considerable low analytical limit (2 CFU mL -1 ) and wide linearity (10–10 8 CFU mL -1 ) for LM were achieved. In addition, the experiments demonstrated that the PIP/Ti 3 C 2 T x R sensor offers satisfactory selectivity, reproducibility and stability.
单核细胞增多性李斯特菌（LM）作为危害最大、致死率最高的病原体之一，给人类带来了各种严重的疾病，因此设计有效的检测策略具有重要意义。本工作通过制备Ti3C2Tx MXenes纳米带（Ti3C2TxR）作为载体，并选择硫堇（Th）同时作为信号探针和功能单体，首次设计了一种LM病原体印迹聚合物（PIP）集成探针电化学传感器来监测LM，在存在LM的条件下，通过Th在Ti 3 C 2 T x R/GCE表面的电聚合进行。从LM印迹腔中洗脱模板后，所制备的PIP/Ti3C2TxR/GCE传感器可以有效地使LM细胞反弹。通过记录Th的峰值电流作为响应信号，当LM细胞重新结合到PIP/Ti3C2TxR/GCE上的LM印迹腔中时，Th的峰电流可以减弱，并且峰值电流变化的绝对值随着LM浓度的增加而增加。在优化了三个关键参数后，LM的分析极限相当低（2 CFU mL-1），线性范围很宽（10–10 8 CFU mL-1）。此外，实验证明PIP/Ti3C2TxR传感器具有良好的选择性、再现性和稳定性。
{"title":"Pathogen-Imprinted Polymer Film Integrated probe/Ti3C2Tx MXenes Electrochemical Sensor for Highly Sensitive Determination of Listeria Monocytogenes","authors":"Xiaohua Jiang, Zhiwen Lv, Wenjie Ding, Ying Zhang, F. Lin","doi":"10.33961/jecst.2022.00269","DOIUrl":"https://doi.org/10.33961/jecst.2022.00269","url":null,"abstract":"As one of the most hazardous and deadliest pathogens, Listeria monocytogenes (LM) posed various serious diseases to the human being, thus designing effective strategy for its detection is of great significance. In this work, by preparing Ti 3 C 2 T x MXenes nanoribbon (Ti 3 C 2 T x R) as carrier and selecting thionine (Th) acted simultaneously as signal probe and functional monomer, a LM pathogen-imprinted polymers (PIP) integrated probe electrochemical sensor was design to monitor LM for the first time, that was carried out through the electropolymerization of Th on the Ti 3 C 2 T x R/GCE surface in the exis-tence of LM. Upon eluting the templates from the LM imprinted cavities, the fabricated PIP/Ti 3 C 2 T x R/GCE sensor can rebound LM cells effectively. By recording the peak current of Th as the response signal, it can be weakened when LM cell was re-bound to the LM imprinted cavity on PIP/Ti 3 C 2 T x R/GCE, and the absolute values of peak current change increase with the increasement of LM concentrations. After optimizing three key parameters, a considerable low analytical limit (2 CFU mL -1 ) and wide linearity (10–10 8 CFU mL -1 ) for LM were achieved. In addition, the experiments demonstrated that the PIP/Ti 3 C 2 T x R sensor offers satisfactory selectivity, reproducibility and stability.","PeriodicalId":15542,"journal":{"name":"Journal of electrochemical science and technology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2022-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42365238","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-04DOI: 10.33961/jecst.2022.00122
Hyunwoo Kim, Dong Inn Kim, W. Yoon
To satisfy the growing demand for high-performance batteries, diverse novel anode materials with high specific capacities have been developed to replace commercial graphite. Among them, cobalt hydroxides have received considerable attention as promising anode materials for lithium-ion batteries as they exhibit a high reversible capacity owing to the additional reaction of LiOH, followed by conversion reaction. In this study, we introduced graphene in the fabrication of Co(OH) 2 -based anode materials to further improve electrochemical performance. The resultant Co(OH) 2 /graphene composite exhibited a larger reversible capacity of ~1090 mAh g -1 , compared with ~705 mAh g -1 for bare Co(OH) 2 . Synchrotron-based analyses were conducted to explore the beneficial effects of graphene on the composite material. The experimental results demonstrate that introducing graphene into Co(OH) 2 facilitates both the conversion and reaction of the LiOH phase and provides additional lithium storage sites. In addition to insights into how the electrochemical performance of composite materials can be improved, this study also provides an effective strategy for designing composite materials.
为了满足对高性能电池日益增长的需求，已经开发出各种高比容量的新型阳极材料来取代商业石墨。其中，氢氧化钴作为锂离子电池的正极材料受到了相当大的关注，因为它们由于LiOH的额外反应和随后的转化反应而表现出高的可逆容量。在本研究中，我们将石墨烯引入Co（OH）2基阳极材料的制备中，以进一步提高电化学性能。与裸Co（OH）2的~705 mAh g-1相比，所得到的Co（OH2/石墨烯复合材料表现出更大的可逆容量，约为1090 mAh g-1。基于同步加速器的分析旨在探索石墨烯对复合材料的有益影响。实验结果表明，将石墨烯引入Co（OH）2中促进了LiOH相的转化和反应，并提供了额外的锂存储位点。除了深入了解如何提高复合材料的电化学性能外，本研究还为设计复合材料提供了一种有效的策略。
{"title":"Enhancing Electrochemical Performance of Co(OH)2 Anode Materials by Introducing Graphene for Next-Generation Li-ion Batteries","authors":"Hyunwoo Kim, Dong Inn Kim, W. Yoon","doi":"10.33961/jecst.2022.00122","DOIUrl":"https://doi.org/10.33961/jecst.2022.00122","url":null,"abstract":"To satisfy the growing demand for high-performance batteries, diverse novel anode materials with high specific capacities have been developed to replace commercial graphite. Among them, cobalt hydroxides have received considerable attention as promising anode materials for lithium-ion batteries as they exhibit a high reversible capacity owing to the additional reaction of LiOH, followed by conversion reaction. In this study, we introduced graphene in the fabrication of Co(OH) 2 -based anode materials to further improve electrochemical performance. The resultant Co(OH) 2 /graphene composite exhibited a larger reversible capacity of ~1090 mAh g -1 , compared with ~705 mAh g -1 for bare Co(OH) 2 . Synchrotron-based analyses were conducted to explore the beneficial effects of graphene on the composite material. The experimental results demonstrate that introducing graphene into Co(OH) 2 facilitates both the conversion and reaction of the LiOH phase and provides additional lithium storage sites. In addition to insights into how the electrochemical performance of composite materials can be improved, this study also provides an effective strategy for designing composite materials.","PeriodicalId":15542,"journal":{"name":"Journal of electrochemical science and technology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2022-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42861814","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-04DOI: 10.33961/jecst.2022.00444
Joo Young Lee, Y. Park
Surface coating of cathodes is an essential process for all-solid-state batteries (ASSBs) based on sulfide electrolytes as it efficiently suppresses interfacial reactions between oxide cathodes and sulfide electrolytes. Based on computational cal-culations, Li 3 PO 4 has been suggested as a promising coating material because of its higher stability with sulfides and its optimal ionic conductivity. However, it has hardly been applied to the coating of ASSBs due to the absence of a suitable coating process, including the selection of source material that is compatible with ASSBs. In this study, polyphosphoric acid (PPA) and (NH 4 ) 2 HPO 4 were used as source materials for preparing a Li 3 PO 4 coating for ASSBs, and the properties of the coating layer and coated cathodes were compared. The Li 3 PO 4 layer fabricated using the (NH 4 ) 2 HPO 4 source was rough and inhomogeneous, which is not suitable for the protection of the cathodes. Moreover, the water-based coating solution with the (NH 4 ) 2 HPO 4 source can deteriorate the electrochemical performance of high-Ni cathodes that are vulnerable to water. In contrast, when an alcohol-based solvent was used, the PPA source enabled the formation of a thin and homogeneous coating layer on the cathode surface. As a consequence, the ASSBs containing the Li 3 PO 4 -coated cathode prepared by the PPA source exhibited significantly enhanced discharge and rate capabilities compared to ASSBs containing a pristine cathode or Li 3 PO 4 -coated cathode prepared by the (NH 4 ) 2 HPO source.
{"title":"Li3PO4 Coated Li[Ni0.75Co0.1Mn0.15]O2 Cathode for All-Solid-State Batteries Based on Sulfide Electrolyte","authors":"Joo Young Lee, Y. Park","doi":"10.33961/jecst.2022.00444","DOIUrl":"https://doi.org/10.33961/jecst.2022.00444","url":null,"abstract":"Surface coating of cathodes is an essential process for all-solid-state batteries (ASSBs) based on sulfide electrolytes as it efficiently suppresses interfacial reactions between oxide cathodes and sulfide electrolytes. Based on computational cal-culations, Li 3 PO 4 has been suggested as a promising coating material because of its higher stability with sulfides and its optimal ionic conductivity. However, it has hardly been applied to the coating of ASSBs due to the absence of a suitable coating process, including the selection of source material that is compatible with ASSBs. In this study, polyphosphoric acid (PPA) and (NH 4 ) 2 HPO 4 were used as source materials for preparing a Li 3 PO 4 coating for ASSBs, and the properties of the coating layer and coated cathodes were compared. The Li 3 PO 4 layer fabricated using the (NH 4 ) 2 HPO 4 source was rough and inhomogeneous, which is not suitable for the protection of the cathodes. Moreover, the water-based coating solution with the (NH 4 ) 2 HPO 4 source can deteriorate the electrochemical performance of high-Ni cathodes that are vulnerable to water. In contrast, when an alcohol-based solvent was used, the PPA source enabled the formation of a thin and homogeneous coating layer on the cathode surface. As a consequence, the ASSBs containing the Li 3 PO 4 -coated cathode prepared by the PPA source exhibited significantly enhanced discharge and rate capabilities compared to ASSBs containing a pristine cathode or Li 3 PO 4 -coated cathode prepared by the (NH 4 ) 2 HPO source.","PeriodicalId":15542,"journal":{"name":"Journal of electrochemical science and technology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2022-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43959270","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-01DOI: 10.33961/jecst.2022.00171
M. García-García
The current global energy supply depends heavily on fossil fuels. This makes technology such as direct water splitting from harvesting solar energy in photoelectrochemical (PEC) systems potentially attractive due to its a promising route for environmentally benign hydrogen production. In this study, undoped and nickel-doped molybdenum oxide photoanodes (called photoanodes S 1 and S 2 respectively) were synthesized through electrodeposition by applying -1.377 V vs Ag/AgCl (3 M KCl) for 3 hours on an FTO-coated glass substrate immersed in molibdatecitrate aqueous solutions at pH 9. Scanning electron microscopy (SEM), atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) were used for microstructural and compositional characterizations of the photoanodes. In addition, the optical and photoelectrochemical characterizations of these photoanodes were performed by UV-Visible spectroscopy, and linear scanning voltammetry (LSV) respectively. The results showed that all the photoanodes produced exhibit conductivity and catalytic properties that make them attractive for water splitting application in a photoelectrochemical cell. In this context, the photoanode S 2 exhibited better photocatalytic activity than the photoanode S 1 . In addition, photoanode S 2 had the lowest optical band-gap energy value (2.58 eV), which would allow better utilization of the solar spectrum.
目前全球能源供应严重依赖化石燃料。这使得光电化学(PEC)系统中收集太阳能的直接水分解等技术具有潜在的吸引力，因为它是一种有前途的环保制氢途径。在本研究中，将-1.377 V vs Ag/AgCl (3 M KCl)电沉积于fto涂层的玻璃基板上，在pH为9的电解质水溶液中浸泡3小时，制备了未掺杂和掺杂镍的氧化钼光阳极(分别称为s1和s2)。利用扫描电镜(SEM)、原子力显微镜(AFM)、能量色散x射线能谱(EDS)和x射线光电子能谱(XPS)对光阳极的微观结构和成分进行了表征。此外，利用紫外可见光谱和线性扫描伏安法(LSV)分别对这些光阳极进行了光学和光电化学表征。结果表明，所制备的所有光阳极都具有导电性和催化性能，使其具有在光电化学电池中用于水分解的吸引力。在这种情况下，光阳极s2比光阳极s1表现出更好的光催化活性。此外，光阳极s2具有最低的光学带隙能值(2.58 eV)，可以更好地利用太阳光谱。
{"title":"Comparative Study of Undoped and Nickel-Doped Molybdenum Oxide Photoanodes for PEC Water Splitting","authors":"M. García-García","doi":"10.33961/jecst.2022.00171","DOIUrl":"https://doi.org/10.33961/jecst.2022.00171","url":null,"abstract":"The current global energy supply depends heavily on fossil fuels. This makes technology such as direct water splitting from harvesting solar energy in photoelectrochemical (PEC) systems potentially attractive due to its a promising route for environmentally benign hydrogen production. In this study, undoped and nickel-doped molybdenum oxide photoanodes (called photoanodes S 1 and S 2 respectively) were synthesized through electrodeposition by applying -1.377 V vs Ag/AgCl (3 M KCl) for 3 hours on an FTO-coated glass substrate immersed in molibdatecitrate aqueous solutions at pH 9. Scanning electron microscopy (SEM), atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) were used for microstructural and compositional characterizations of the photoanodes. In addition, the optical and photoelectrochemical characterizations of these photoanodes were performed by UV-Visible spectroscopy, and linear scanning voltammetry (LSV) respectively. The results showed that all the photoanodes produced exhibit conductivity and catalytic properties that make them attractive for water splitting application in a photoelectrochemical cell. In this context, the photoanode S 2 exhibited better photocatalytic activity than the photoanode S 1 . In addition, photoanode S 2 had the lowest optical band-gap energy value (2.58 eV), which would allow better utilization of the solar spectrum.","PeriodicalId":15542,"journal":{"name":"Journal of electrochemical science and technology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43096632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-01DOI: 10.33961/jecst.2022.00290
T. Amiri, T. Etsell, P. Sarkar
The use of microwaves as the energy source for synthesis and sintering of ceramics offers substantial advantages compared to conventional gas-fired and electric resistance furnaces. Benefits include much shorter processing times and reaching the sintering temperature more quickly, resulting in superior final product quality. Most oxide ceramics poorly interact with microwave irradiation at low temperatures; thus, a more complex setup including a susceptor is needed, which makes the whole process very complicated. This investigation pursued a new approach, which enabled us to use microwave irradiation directly in poorly coupled oxides. In many solid-state electrochemical devices, the support is either metal or can be reduced to metal. Metal powders in the support can act as an internal susceptor and heat the entire cell. Then sufficient interaction of microwave irradiation and ceramic material can occur as the sample temperature increases. This microwave heating and exothermic reaction of oxidation of the support can sinter the ceramic very efficiently without any external susceptor. In this study, yttria stabilized zirconia (YSZ) and a Ni-YSZ cermet support were used as an example. The cermet was used as the support, and a YSZ electrolyte was coated and sintered directly using microwave irradiation without the use of any susceptor. The results were compared to a similar cell prepared using a conventional electric furnace. The leakage test and full cell power measurement results revealed a fully leak-free electrolyte. Scanning electron microscopy and density measurements show that microwave sintered samples have lower open porosity in the electrode support than conventional heat treatment. This technique offers an efficient way to directly use microwave irradiation to sinter thin film ceramics without a susceptor.
{"title":"Direct Microwave Sintering of Poorly Coupled Ceramics in Electrochemical Devices","authors":"T. Amiri, T. Etsell, P. Sarkar","doi":"10.33961/jecst.2022.00290","DOIUrl":"https://doi.org/10.33961/jecst.2022.00290","url":null,"abstract":"The use of microwaves as the energy source for synthesis and sintering of ceramics offers substantial advantages compared to conventional gas-fired and electric resistance furnaces. Benefits include much shorter processing times and reaching the sintering temperature more quickly, resulting in superior final product quality. Most oxide ceramics poorly interact with microwave irradiation at low temperatures; thus, a more complex setup including a susceptor is needed, which makes the whole process very complicated. This investigation pursued a new approach, which enabled us to use microwave irradiation directly in poorly coupled oxides. In many solid-state electrochemical devices, the support is either metal or can be reduced to metal. Metal powders in the support can act as an internal susceptor and heat the entire cell. Then sufficient interaction of microwave irradiation and ceramic material can occur as the sample temperature increases. This microwave heating and exothermic reaction of oxidation of the support can sinter the ceramic very efficiently without any external susceptor. In this study, yttria stabilized zirconia (YSZ) and a Ni-YSZ cermet support were used as an example. The cermet was used as the support, and a YSZ electrolyte was coated and sintered directly using microwave irradiation without the use of any susceptor. The results were compared to a similar cell prepared using a conventional electric furnace. The leakage test and full cell power measurement results revealed a fully leak-free electrolyte. Scanning electron microscopy and density measurements show that microwave sintered samples have lower open porosity in the electrode support than conventional heat treatment. This technique offers an efficient way to directly use microwave irradiation to sinter thin film ceramics without a susceptor.","PeriodicalId":15542,"journal":{"name":"Journal of electrochemical science and technology","volume":"1 1","pages":""},"PeriodicalIF":3.7,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41333482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-01DOI: 10.33961/jecst.2022.00115
Jung-goo Choi, Kahyun Ham, Sungyool Bong, Jaeyoung Lee
In a direct methanol fuel cell system (DMFC), one of the drawbacks is methanol crossover. Methanol from the anode passes through the membrane and enters the cathode, causing mixed potential in the cell. Only Pt-based catalysts are capable of operating as cathode for oxygen reduction reaction (ORR) in a harsh acidic condition of DMFC. However, it causes mixed potential due to high activity toward methanol oxidation reaction of Pt. To overcome this situation, developing Pt-based catalyst that has methanol tolerance is significant, by controlling reactant adsorption or reaction kinetics. Pt/C decorated with phosphate ion was prepared by modified polyol method as cathode catalyst in DMFC. Phosphate ions, bonded to the carbon of Pt/C, surround free Pt surface and block only methanol adsorption on Pt, not oxygen. It leads to the suppression of methanol oxidation in an oxygen atmosphere, resulting in high DMFC performance compared to pristine Pt/C.
{"title":"Phosphate-decorated Pt Nanoparticles as Methanol-tolerant Oxygen Reduction Electrocatalyst for Direct Methanol Fuel Cells","authors":"Jung-goo Choi, Kahyun Ham, Sungyool Bong, Jaeyoung Lee","doi":"10.33961/jecst.2022.00115","DOIUrl":"https://doi.org/10.33961/jecst.2022.00115","url":null,"abstract":"In a direct methanol fuel cell system (DMFC), one of the drawbacks is methanol crossover. Methanol from the anode passes through the membrane and enters the cathode, causing mixed potential in the cell. Only Pt-based catalysts are capable of operating as cathode for oxygen reduction reaction (ORR) in a harsh acidic condition of DMFC. However, it causes mixed potential due to high activity toward methanol oxidation reaction of Pt. To overcome this situation, developing Pt-based catalyst that has methanol tolerance is significant, by controlling reactant adsorption or reaction kinetics. Pt/C decorated with phosphate ion was prepared by modified polyol method as cathode catalyst in DMFC. Phosphate ions, bonded to the carbon of Pt/C, surround free Pt surface and block only methanol adsorption on Pt, not oxygen. It leads to the suppression of methanol oxidation in an oxygen atmosphere, resulting in high DMFC performance compared to pristine Pt/C.","PeriodicalId":15542,"journal":{"name":"Journal of electrochemical science and technology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44716234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-01DOI: 10.33961/jecst.2022.00241
A. K. Niaz, Hyung-Tae Lim
In this study, the stability of an anion exchange membrane water electrolyzer (AEMWE) cell was evaluated in an on-off cycling operation with respect to an applied electric bias, i.e., a current density of 500 mA cm -2 , and an open circuit. The ohmic and polarization resistances of the system were monitored during operation (~800 h) using electrochemical impedance spectra. Specific consideration was given to the ohmic resistance of the cell, especially that of the membrane under on-off cycling conditions, by consistently feeding the cell with KOH solution. Owing to an excess feed solution, a momen-tary increase in the polarization resistance was observed immediately after the open-circuit. The excess feed solution was mostly recovered by subjecting the cell to the applied electric bias. Stability tests on the AEMWE cell under on-off cycling with continuous feeding even under an open circuit can guarantee long-term stability by avoiding an irreversible increase in ohmic and polarization resistances.
{"title":"Stability Tests on Anion Exchange Membrane Water Electrolyzer under On-Off Cycling with Continuous Solution Feeding","authors":"A. K. Niaz, Hyung-Tae Lim","doi":"10.33961/jecst.2022.00241","DOIUrl":"https://doi.org/10.33961/jecst.2022.00241","url":null,"abstract":"In this study, the stability of an anion exchange membrane water electrolyzer (AEMWE) cell was evaluated in an on-off cycling operation with respect to an applied electric bias, i.e., a current density of 500 mA cm -2 , and an open circuit. The ohmic and polarization resistances of the system were monitored during operation (~800 h) using electrochemical impedance spectra. Specific consideration was given to the ohmic resistance of the cell, especially that of the membrane under on-off cycling conditions, by consistently feeding the cell with KOH solution. Owing to an excess feed solution, a momen-tary increase in the polarization resistance was observed immediately after the open-circuit. The excess feed solution was mostly recovered by subjecting the cell to the applied electric bias. Stability tests on the AEMWE cell under on-off cycling with continuous feeding even under an open circuit can guarantee long-term stability by avoiding an irreversible increase in ohmic and polarization resistances.","PeriodicalId":15542,"journal":{"name":"Journal of electrochemical science and technology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49088991","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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