Pub Date : 2024-12-03DOI: 10.3866/PKU.WHXB202404023
Xin Han , Zhihao Cheng , Jinfeng Zhang , Jie Liu , Cheng Zhong , Wenbin Hu
The efficient electrocatalysts towards the oxygen evolution reaction (OER) are vital for water splitting. Herein, a novel FeCoCrMnBS high-entropy (Oxy) hydroxide (HEH) is synthesized on a nickel foam (NF) surface via a facile approach. The FeCoCrMnBS HEH possesses a porous morphology composed of plentiful ultra-thin nanosheets with the amorphous structure. The obtained FeCoCrMnBS/NF electrode exhibits exceptional electrocatalytic OER activity in alkaline solution, requiring only 290 mV overpotential for 100 mA · cm−2. Moreover, this catalyst displays a long-term durability of over 120 h at 10 mA · cm−2. The enhanced catalytic performance benefits from the unique amorphous structure and the positive synergy effect between B and S, promoting the formation of SO42− and thus weakening the adsorption of intermediates in OER on the catalyst surface. This work provides a new strategy for the design of desirable OER electrocatalysts.
{"title":"Design of amorphous high-entropy FeCoCrMnBS (Oxy) hydroxides for boosting oxygen evolution reaction","authors":"Xin Han , Zhihao Cheng , Jinfeng Zhang , Jie Liu , Cheng Zhong , Wenbin Hu","doi":"10.3866/PKU.WHXB202404023","DOIUrl":"10.3866/PKU.WHXB202404023","url":null,"abstract":"<div><div>The efficient electrocatalysts towards the oxygen evolution reaction (OER) are vital for water splitting. Herein, a novel FeCoCrMnBS high-entropy (Oxy) hydroxide (HEH) is synthesized on a nickel foam (NF) surface <em>via</em> a facile approach. The FeCoCrMnBS HEH possesses a porous morphology composed of plentiful ultra-thin nanosheets with the amorphous structure. The obtained FeCoCrMnBS/NF electrode exhibits exceptional electrocatalytic OER activity in alkaline solution, requiring only 290 mV overpotential for 100 mA · cm<sup>−2</sup>. Moreover, this catalyst displays a long-term durability of over 120 h at 10 mA · cm<sup>−2</sup>. The enhanced catalytic performance benefits from the unique amorphous structure and the positive synergy effect between B and S, promoting the formation of SO<sub>4</sub><sup>2−</sup> and thus weakening the adsorption of intermediates in OER on the catalyst surface. This work provides a new strategy for the design of desirable OER electrocatalysts.</div></div>","PeriodicalId":6964,"journal":{"name":"物理化学学报","volume":"41 4","pages":"Article 100033"},"PeriodicalIF":10.8,"publicationDate":"2024-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143093639","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-03DOI: 10.3866/PKU.WHXB202404012
Xue Dong , Xiaofu Sun , Shuaiqiang Jia , Shitao Han , Dawei Zhou , Ting Yao , Min Wang , Minghui Fang , Haihong Wu , Buxing Han
Copper-based electrocatalysts have great potential to produce high-value products in CO2 reduction reaction (CO2RR), offering a promising way to achieve negative carbon emissions. Additionally, achieving ampere-level currents is crucial for realizing the industrialization of multi-carbon (C2+) products. However, the C2+ selectivity at industrial current densities remains unsatisfactory due to complex electron transport processes and inevitable side reactions. Herein, we developed a carbon-modification strategy aimed at optimizing the local environment and regulating the adsorption of intermediates at Cu active sites. Our findings demonstrated the effectiveness of Cu-Cx catalysts (where ‘x’ denoted the atomic percentage of C in the catalysts) in facilitating CO2RR for producing C2+ products. Especially, over Cu–C6%, the current density could reach to 1.25 A cm−2 at −0.72 V vs. RHE (versus reversible hydrogen electrode) in a flow cell, and the Faradaic efficiency (FE) of C2H4 and C2+ products could reach to 54.4 % and 80.2 %, respectively. In situ spectral analysis and density functional theory (DFT) calculations showed that the presence of C regulated the adsorption of ∗CO on Cu surface, reduced the energy barrier of C–C coupling, thus promoting the production of C2+ products.
{"title":"Electrochemical CO2 reduction to C2+ products with ampere-level current on carbon-modified copper catalysts","authors":"Xue Dong , Xiaofu Sun , Shuaiqiang Jia , Shitao Han , Dawei Zhou , Ting Yao , Min Wang , Minghui Fang , Haihong Wu , Buxing Han","doi":"10.3866/PKU.WHXB202404012","DOIUrl":"10.3866/PKU.WHXB202404012","url":null,"abstract":"<div><div>Copper-based electrocatalysts have great potential to produce high-value products in CO<sub>2</sub> reduction reaction (CO<sub>2</sub>RR), offering a promising way to achieve negative carbon emissions. Additionally, achieving ampere-level currents is crucial for realizing the industrialization of multi-carbon (C<sub>2+</sub>) products. However, the C<sub>2+</sub> selectivity at industrial current densities remains unsatisfactory due to complex electron transport processes and inevitable side reactions. Herein, we developed a carbon-modification strategy aimed at optimizing the local environment and regulating the adsorption of intermediates at Cu active sites. Our findings demonstrated the effectiveness of Cu-C<sub><em>x</em></sub> catalysts (where ‘<em>x</em>’ denoted the atomic percentage of C in the catalysts) in facilitating CO<sub>2</sub>RR for producing C<sub>2+</sub> products. Especially, over Cu–C<sub>6%</sub>, the current density could reach to 1.25 A cm<sup>−2</sup> at −0.72 V <em>vs</em>. RHE (<em>versus</em> reversible hydrogen electrode) in a flow cell, and the Faradaic efficiency (FE) of C<sub>2</sub>H<sub>4</sub> and C<sub>2+</sub> products could reach to 54.4 % and 80.2 %, respectively. <em>In situ</em> spectral analysis and density functional theory (DFT) calculations showed that the presence of C regulated the adsorption of ∗CO on Cu surface, reduced the energy barrier of C–C coupling, thus promoting the production of C<sub>2+</sub> products.</div></div>","PeriodicalId":6964,"journal":{"name":"物理化学学报","volume":"41 3","pages":"Article 100024"},"PeriodicalIF":10.8,"publicationDate":"2024-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143104724","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Water scarcity has become a prominent global challenge in the twenty-first century, prompting the rapid advancement of desalination technology. Capacitive deionization (CDI) stands out as a cost-effective solution for sustainable water purification. The electrode material plays a pivotal role in capacitive deionization, impacting the salt ion removal and charge storage capacity. Carbon-based materials, characterized by high surface area and electrical conductivity, are ideal materials for capacitive deionization. However, their effectiveness in salt ion removal is hindered by unclear pore structures and poor wettability, limiting salt ion transport and storage. In this study, nitrogen-doped hierarchical porous carbon is successfully synthesized through the carbonization of MOF-5 and melamine mixtures, wherein melamine serves as both a nitrogen source and porogenic agent. Through optimization of carbonization temperature, the resulting MOF-5-derived nanoporous carbon (referred to as NPC-800) retains the cubic morphology of MOF-5, possesses a large surface area (754.34 m2 g−1), high nitrogen content (10.13 %), and favorable wettability. Electrochemical analysis reveals that the NPC-800 electrode demonstrates specific capacities of 91.8, 76.1, 66.3, 51.0, 28.0, and 15.2 mAh g−1 at current densities of 0.2, 0.5, 1.0, 2.0, 4.0, and 6.0 A g−1, respectively, outperforming NPC-700 (26.3, 19.7, 13.1, 6.90, 2.30, and 1.30 mAh g−1) and NPC-900 (46.0, 37.8, 30.4, 21.3, 11.7, and 7.50 mAh g−1). The superior electrochemical performance of NPC-800 can be attributed to its maximal specific surface area, abundant pore structure, and optimal wettability, facilitating increased active sites for salt ion adsorption and diffusion. Moreover, NPC-800 exhibits low intrinsic resistance, rapid ion transfer kinetics, and exceptional cycling stability (50,000 cycles) with 100 % capacity retention at 5 A g−1. Further investigation into the CDI performance of NPC electrodes under different applied voltages (0.8, 1.0, and 1.2 V) and initial NaCl solution concentrations (100, 300, and 500 mg L−1) demonstrates the superior adsorption capacity of the NPC-800 electrode compared to the other two electrodes. Specifically, at 1.2 V in a 500 mg L−1 salt solution, NPC-800 exhibits a faster salt adsorption rate (2.8 mg g−1 min−1) and higher salt adsorption capacity (24.17 mg g−1) compared to NPC-700 and NPC-900. Consequently, the melamine-assisted synthesis of N-doped porous carbon materials holds promise as an optimal choice for capacitive deionization.
{"title":"MOF-templated synthesis of nitrogen-doped carbon for enhanced electrochemical sodium ion storage and removal","authors":"Zhuo Wang, Xue Bai, Kexin Zhang, Hongzhi Wang, Jiabao Dong, Yuan Gao, Bin Zhao","doi":"10.3866/PKU.WHXB202405002","DOIUrl":"10.3866/PKU.WHXB202405002","url":null,"abstract":"<div><div>Water scarcity has become a prominent global challenge in the twenty-first century, prompting the rapid advancement of desalination technology. Capacitive deionization (CDI) stands out as a cost-effective solution for sustainable water purification. The electrode material plays a pivotal role in capacitive deionization, impacting the salt ion removal and charge storage capacity. Carbon-based materials, characterized by high surface area and electrical conductivity, are ideal materials for capacitive deionization. However, their effectiveness in salt ion removal is hindered by unclear pore structures and poor wettability, limiting salt ion transport and storage. In this study, nitrogen-doped hierarchical porous carbon is successfully synthesized through the carbonization of MOF-5 and melamine mixtures, wherein melamine serves as both a nitrogen source and porogenic agent. Through optimization of carbonization temperature, the resulting MOF-5-derived nanoporous carbon (referred to as NPC-800) retains the cubic morphology of MOF-5, possesses a large surface area (754.34 m<sup>2</sup> g<sup>−1</sup>), high nitrogen content (10.13 %), and favorable wettability. Electrochemical analysis reveals that the NPC-800 electrode demonstrates specific capacities of 91.8, 76.1, 66.3, 51.0, 28.0, and 15.2 mAh g<sup>−1</sup> at current densities of 0.2, 0.5, 1.0, 2.0, 4.0, and 6.0 A g<sup>−1</sup>, respectively, outperforming NPC-700 (26.3, 19.7, 13.1, 6.90, 2.30, and 1.30 mAh g<sup>−1</sup>) and NPC-900 (46.0, 37.8, 30.4, 21.3, 11.7, and 7.50 mAh g<sup>−1</sup>). The superior electrochemical performance of NPC-800 can be attributed to its maximal specific surface area, abundant pore structure, and optimal wettability, facilitating increased active sites for salt ion adsorption and diffusion. Moreover, NPC-800 exhibits low intrinsic resistance, rapid ion transfer kinetics, and exceptional cycling stability (50,000 cycles) with 100 % capacity retention at 5 A g<sup>−1</sup>. Further investigation into the CDI performance of NPC electrodes under different applied voltages (0.8, 1.0, and 1.2 V) and initial NaCl solution concentrations (100, 300, and 500 mg L<sup>−1</sup>) demonstrates the superior adsorption capacity of the NPC-800 electrode compared to the other two electrodes. Specifically, at 1.2 V in a 500 mg L<sup>−1</sup> salt solution, NPC-800 exhibits a faster salt adsorption rate (2.8 mg g<sup>−1</sup> min<sup>−1</sup>) and higher salt adsorption capacity (24.17 mg g<sup>−1</sup>) compared to NPC-700 and NPC-900. Consequently, the melamine-assisted synthesis of N-doped porous carbon materials holds promise as an optimal choice for capacitive deionization.</div></div>","PeriodicalId":6964,"journal":{"name":"物理化学学报","volume":"41 3","pages":"Article 100026"},"PeriodicalIF":10.8,"publicationDate":"2024-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143181308","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-03DOI: 10.3866/PKU.WHXB202406012
Pei Li, Yuenan Zheng, Zhankai Liu, An-Hui Lu
Boron-containing zeolites can catalyze the oxidative dehydrogenation of propane (ODHP) to produce propylene. Enhancing the quantity of active boron-oxygen species and regulating the positioning of these species within the zeolite are the main challenges in developing efficient boron-based catalysts. In this study, a boron-containing zeolite catalyst with exposed (010) crystal facets, referred to as the MFI-type boron-containing zeolite (BMFI), was synthesized using a urea-assisted hydrothermal method. The research indicates that the addition of an appropriate amount of urea can regulate the morphology of the zeolite, with its short-axis flake-like structure enhancing the accessibility of active boron sites and anchoring a higher content of active boron-oxygen species through hydrogen bonding, which significantly improves the ODHP activity and olefin selectivity of the catalyst. The propane conversion rate reached 20 %, with a propylene selectivity of 62.3 % and a total olefin selectivity of 81.3 % at 520 °C. Compared to the ellipsoidal boron-containing catalyst formed without urea, the sheet-like BMFI catalyst exhibited nearly a 20-fold increase in the reaction rate of propane. The flake-like BMFI possesses a greater number of framework tetrahedrally coordinated boron (B[4]) and defective boron species (B[3]a and B[3]b), and active boron structural evolution occurred during the reaction process, with B[3]a and B[3]b being the active sites for the catalytic reaction. This study provides a reference for the structural design and regulation of boron-based catalysts for the oxidative dehydrogenation of light alkanes.
{"title":"Boron-containing MFI zeolite: Microstructure control and its performance of propane oxidative dehydrogenation","authors":"Pei Li, Yuenan Zheng, Zhankai Liu, An-Hui Lu","doi":"10.3866/PKU.WHXB202406012","DOIUrl":"10.3866/PKU.WHXB202406012","url":null,"abstract":"<div><div>Boron-containing zeolites can catalyze the oxidative dehydrogenation of propane (ODHP) to produce propylene. Enhancing the quantity of active boron-oxygen species and regulating the positioning of these species within the zeolite are the main challenges in developing efficient boron-based catalysts. In this study, a boron-containing zeolite catalyst with exposed (010) crystal facets, referred to as the MFI-type boron-containing zeolite (BMFI), was synthesized using a urea-assisted hydrothermal method. The research indicates that the addition of an appropriate amount of urea can regulate the morphology of the zeolite, with its short-axis flake-like structure enhancing the accessibility of active boron sites and anchoring a higher content of active boron-oxygen species through hydrogen bonding, which significantly improves the ODHP activity and olefin selectivity of the catalyst. The propane conversion rate reached 20 %, with a propylene selectivity of 62.3 % and a total olefin selectivity of 81.3 % at 520 °C. Compared to the ellipsoidal boron-containing catalyst formed without urea, the sheet-like BMFI catalyst exhibited nearly a 20-fold increase in the reaction rate of propane. The flake-like BMFI possesses a greater number of framework tetrahedrally coordinated boron (B[4]) and defective boron species (B[3]<sup>a</sup> and B[3]<sup>b</sup>), and active boron structural evolution occurred during the reaction process, with B[3]<sup>a</sup> and B[3]<sup>b</sup> being the active sites for the catalytic reaction. This study provides a reference for the structural design and regulation of boron-based catalysts for the oxidative dehydrogenation of light alkanes.</div></div>","PeriodicalId":6964,"journal":{"name":"物理化学学报","volume":"41 4","pages":"Article 100034"},"PeriodicalIF":10.8,"publicationDate":"2024-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143093636","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-03DOI: 10.3866/PKU.WHXB202407025
Pengyu Dong , Yue Jiang , Zhengchi Yang , Licheng Liu , Gu Li , Xinyang Wen , Zhen Wang , Xinbo Shi , Guofu Zhou , Jun-Ming Liu , Jinwei Gao
Organic-inorganic metal halide perovskite solar cells (PSCs) are favorable candidates for next-generation solar cells, due to their excellent photovoltaic performance and promising low-cost fabrication process. Particularly, tin oxide (SnO2), with excellent charge mobility and extraction efficiency, is widely used as electron transport layers (ETLs), and the efficiency of the corresponding n-i-p-type perovskites has been certified as high as 26.21 % in single-junction devices. The SnO2 layer serves as the substrate for the growth of perovskite films, determining the crystalline quality and the buried interface of perovskite films. However, due to the different thermal expansion coefficient of SnO2 and perovskite, the subsequent perovskite annealing process leads to the residual stress at the buried interfaces and lattice distortion in the perovskite films, which seriously affects their optoelectronic performance and stability. To release this interfacial stress, researchers have made some progress by applying different polymers and small molecules to the SnO2/perovskite interface as a buffer layer. Among these, two-dimensional (2D) nanosheets with high carrier mobility, a wide bandgap range, and excellent optical absorption properties are promising, especially 2D NbSe2 nanosheets showing the advantages of solution-processability, high intrinsic conductivity and clean smooth surface, namely without dangling bonded atoms. Herein, 2D NbSe2 nanosheets have been introduced at the SnO2/perovskite interface to release the undesired residual tensile strain in perovskite films and to form a more matched interfacial energy level alignment. As a result, we have obtained a high-quality perovskite film and further an improved photovoltaic performance. The PCE has been increased from 21.81 % to 24.05 %. The unencapsulated cell maintained 91 % of the initial efficiency after aging over 1000 h under atmospheric condition.
{"title":"NbSe2 nanosheets improved the buried interface for perovskite solar cells","authors":"Pengyu Dong , Yue Jiang , Zhengchi Yang , Licheng Liu , Gu Li , Xinyang Wen , Zhen Wang , Xinbo Shi , Guofu Zhou , Jun-Ming Liu , Jinwei Gao","doi":"10.3866/PKU.WHXB202407025","DOIUrl":"10.3866/PKU.WHXB202407025","url":null,"abstract":"<div><div>Organic-inorganic metal halide perovskite solar cells (PSCs) are favorable candidates for next-generation solar cells, due to their excellent photovoltaic performance and promising low-cost fabrication process. Particularly, tin oxide (SnO<sub>2</sub>), with excellent charge mobility and extraction efficiency, is widely used as electron transport layers (ETLs), and the efficiency of the corresponding n-i-p-type perovskites has been certified as high as 26.21 % in single-junction devices. The SnO<sub>2</sub> layer serves as the substrate for the growth of perovskite films, determining the crystalline quality and the buried interface of perovskite films. However, due to the different thermal expansion coefficient of SnO<sub>2</sub> and perovskite, the subsequent perovskite annealing process leads to the residual stress at the buried interfaces and lattice distortion in the perovskite films, which seriously affects their optoelectronic performance and stability. To release this interfacial stress, researchers have made some progress by applying different polymers and small molecules to the SnO<sub>2</sub>/perovskite interface as a buffer layer. Among these, two-dimensional (2D) nanosheets with high carrier mobility, a wide bandgap range, and excellent optical absorption properties are promising, especially 2D NbSe<sub>2</sub> nanosheets showing the advantages of solution-processability, high intrinsic conductivity and clean smooth surface, namely without dangling bonded atoms. Herein, 2D NbSe<sub>2</sub> nanosheets have been introduced at the SnO<sub>2</sub>/perovskite interface to release the undesired residual tensile strain in perovskite films and to form a more matched interfacial energy level alignment. As a result, we have obtained a high-quality perovskite film and further an improved photovoltaic performance. The PCE has been increased from 21.81 % to 24.05 %. The unencapsulated cell maintained 91 % of the initial efficiency after aging over 1000 h under atmospheric condition.</div></div>","PeriodicalId":6964,"journal":{"name":"物理化学学报","volume":"41 3","pages":"Article 100029"},"PeriodicalIF":10.8,"publicationDate":"2024-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143181298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-03DOI: 10.3866/PKU.WHXB202406009
Qiqi Li , Su Zhang , Yuting Jiang , Linna Zhu , Nannan Guo , Jing Zhang , Yutong Li , Tong Wei , Zhuangjun Fan
Activated carbons are widely used as the electrode material for supercapacitors owing to their large surface area, moderate conductivity, and outstanding electrochemical stability. However, large-surface-area activated carbons usually show low density and poor volumetric energy storage performance, which is difficult to meet the development of devices miniaturization. Mechanical compression is a simple and effective method to improve the density of the activated carbons. However, most of the studies focus on mechanical compression of the as-prepared porous carbon materials. Preparation of high-density activated carbons by mechanical compression of the carbon precursors has been proposed. But the surface area and porous structure evolution, and the possible mechanism have rarely investigated. Herein, we propose a universal method to improve the density of the activated carbons by mechanical compression of the precursors before activation. The influence of mechanical compression on the surface area, porous structure, and capacitive energy storage performance of the activated carbons prepared by two typical methods, outside-in activation (carbon powder/KOH mixture) and homogeneous ion activation (pyrolysis of potassium-containing salts), are studied. Mechanical compression of the precursors can generally improve the activation reaction efficiency, as well as the density and volumetric capacitive performance of the activated carbons. However, the surface area and porous structure evolution mainly depend on the carbon precursor and pore-forming process. For outside-in activation, the surface area and porosity of the activated carbons show a first increasing and then decreasing trend with the increase of mechanical pressure. This is because mechanical compression enhances the contact between the carbon precursors and activator through eliminating the voids between particles, significantly improves the activation efficiency. For homogeneous ion activation, the surface area and porosity of activated carbons show a trend of decreasing first and then increasing. The reason is deduced as compressed precursors inhibit the rapid release of active gas molecules (H2O, CO2etc.) produced during pyrolysis. These gas molecules further participate in the activation etching reaction and promote the activation efficiency. The optimized sample shows high gravimetric and volumetric capacitances of 316 F g−1/291 F cm−3 and 131 F g−1/92 F cm−3 at 1 A g−1 in aqueous and organic electrolytes, respectively. This work provides a simple way for design and preparation of activated carbons with large surface area and high density.
{"title":"Preparation of high density activated carbon by mechanical compression of precursors for compact capacitive energy storage","authors":"Qiqi Li , Su Zhang , Yuting Jiang , Linna Zhu , Nannan Guo , Jing Zhang , Yutong Li , Tong Wei , Zhuangjun Fan","doi":"10.3866/PKU.WHXB202406009","DOIUrl":"10.3866/PKU.WHXB202406009","url":null,"abstract":"<div><div>Activated carbons are widely used as the electrode material for supercapacitors owing to their large surface area, moderate conductivity, and outstanding electrochemical stability. However, large-surface-area activated carbons usually show low density and poor volumetric energy storage performance, which is difficult to meet the development of devices miniaturization. Mechanical compression is a simple and effective method to improve the density of the activated carbons. However, most of the studies focus on mechanical compression of the as-prepared porous carbon materials. Preparation of high-density activated carbons by mechanical compression of the carbon precursors has been proposed. But the surface area and porous structure evolution, and the possible mechanism have rarely investigated. Herein, we propose a universal method to improve the density of the activated carbons by mechanical compression of the precursors before activation. The influence of mechanical compression on the surface area, porous structure, and capacitive energy storage performance of the activated carbons prepared by two typical methods, outside-in activation (carbon powder/KOH mixture) and homogeneous ion activation (pyrolysis of potassium-containing salts), are studied. Mechanical compression of the precursors can generally improve the activation reaction efficiency, as well as the density and volumetric capacitive performance of the activated carbons. However, the surface area and porous structure evolution mainly depend on the carbon precursor and pore-forming process. For outside-in activation, the surface area and porosity of the activated carbons show a first increasing and then decreasing trend with the increase of mechanical pressure. This is because mechanical compression enhances the contact between the carbon precursors and activator through eliminating the voids between particles, significantly improves the activation efficiency. For homogeneous ion activation, the surface area and porosity of activated carbons show a trend of decreasing first and then increasing. The reason is deduced as compressed precursors inhibit the rapid release of active gas molecules (H<sub>2</sub>O, CO<sub>2</sub> <em>etc</em>.) produced during pyrolysis. These gas molecules further participate in the activation etching reaction and promote the activation efficiency. The optimized sample shows high gravimetric and volumetric capacitances of 316 F g<sup>−1</sup>/291 F cm<sup>−3</sup> and 131 F g<sup>−1</sup>/92 F cm<sup>−3</sup> at 1 A g<sup>−1</sup> in aqueous and organic electrolytes, respectively. This work provides a simple way for design and preparation of activated carbons with large surface area and high density.</div></div>","PeriodicalId":6964,"journal":{"name":"物理化学学报","volume":"41 3","pages":"Article 100028"},"PeriodicalIF":10.8,"publicationDate":"2024-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143181297","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-02DOI: 10.3866/PKU.WHXB202311032
Ping Ye , Lingshuang Qin , Mengyao He , Fangfang Wu , Zengye Chen , Mingxing Liang , Libo Deng
With the growth of batteries, electroplating, and mining industries, heavy metal ions such as cadmium (Cd2+) are being discharged on a massive scale, thus posing a severe threat to the environment. Conventional techniques for removing Cd2+ from wastewater with low concentrations still suffer from slow kinetics and secondary pollution. A carbon-based capacitive deionization (CDI) system is highly desired but encounters a severe co-ion expulsion effect. Herein, we developed CDI systems based on surface charge-modulated porous carbon and an asymmetric configuration. This was achieved by first preparing porous carbons through facile microwave pyrolysis of lotus leaf followed by KOH activation. The morphology, pore structure, heteroatom content, surface charge, and electrochemical behavior of porous carbons were investigated by adjusting the mass ratio of KOH to carbon. The lotus leaf-derived carbons show a morphology of nanosheet-like thin carbon (NSTC), with their specific surface areas increasing with the amount of KOH used for activation. In contrast, the heteroatom (i.e., nitrogen and oxygen) contents decrease with the increase in the mass ratio of KOH to carbon, resulting in a more positive surface charge. Notably, the NSTC with a mass ratio of 3 for KOH/carbon (NSTC-3) displays an ultrahigh specific surface area of 3705.0 m2 g−1, and a specific capacitance of 92.5 F g−1 at a current density of 0.5 A g−1 when coupled with a commercial activated carbon in an asymmetric YP-50F//NSTC-3 supercapacitor. Consequently, the CDI cell equipped with a YP-50F as the anode and a NSTC-3 as the cathode exhibits a high specific adsorption capacity of 88.6 mgCd·gcathode−1 at 1.2 V in a 100 mg L−1 Cd2+ solution, which is about 36.3 % higher than that of the symmetrical configuration NSTC-3//NSTC-3. Furthermore, 71 % of the initial removal capacity of the YP-50F//NSTC-3 system is retained after 7 cycles of charging and discharging. Characterizations of the cathode after the adsorption process indicate that the Cd2+ is captured by both electrical-double-layer and pseudocapacitive mechanisms. Additionally, CdCO3 precipitate is also responsible for Cd2+ removal, which might be ascribed to the reaction of dissolved CO2 in aqueous media with Cd2+ under the electrified action. The high removal performance and excellent cycling stability are attributed to the tunability of the surface charge properties and the asymmetric configuration, which minimizes the co-ion expulsion and modulates potential distribution. This study provides a novel avenue to design biochar-based configurations for electrified water treatment.
{"title":"Potential of zero charge-mediated electrochemical capture of cadmium ions from wastewater by lotus leaf-derived porous carbons","authors":"Ping Ye , Lingshuang Qin , Mengyao He , Fangfang Wu , Zengye Chen , Mingxing Liang , Libo Deng","doi":"10.3866/PKU.WHXB202311032","DOIUrl":"10.3866/PKU.WHXB202311032","url":null,"abstract":"<div><div>With the growth of batteries, electroplating, and mining industries, heavy metal ions such as cadmium (Cd<sup>2+</sup>) are being discharged on a massive scale, thus posing a severe threat to the environment. Conventional techniques for removing Cd<sup>2+</sup> from wastewater with low concentrations still suffer from slow kinetics and secondary pollution. A carbon-based capacitive deionization (CDI) system is highly desired but encounters a severe co-ion expulsion effect. Herein, we developed CDI systems based on surface charge-modulated porous carbon and an asymmetric configuration. This was achieved by first preparing porous carbons through facile microwave pyrolysis of lotus leaf followed by KOH activation. The morphology, pore structure, heteroatom content, surface charge, and electrochemical behavior of porous carbons were investigated by adjusting the mass ratio of KOH to carbon. The lotus leaf-derived carbons show a morphology of nanosheet-like thin carbon (NSTC), with their specific surface areas increasing with the amount of KOH used for activation. In contrast, the heteroatom (<em>i.e</em>., nitrogen and oxygen) contents decrease with the increase in the mass ratio of KOH to carbon, resulting in a more positive surface charge. Notably, the NSTC with a mass ratio of 3 for KOH/carbon (NSTC-3) displays an ultrahigh specific surface area of 3705.0 m<sup>2</sup> g<sup>−1</sup>, and a specific capacitance of 92.5 F g<sup>−1</sup> at a current density of 0.5 A g<sup>−1</sup> when coupled with a commercial activated carbon in an asymmetric YP-50F//NSTC-3 supercapacitor. Consequently, the CDI cell equipped with a YP-50F as the anode and a NSTC-3 as the cathode exhibits a high specific adsorption capacity of 88.6 mg<sub>Cd</sub>·g<sub>cathode</sub><sup>−1</sup> at 1.2 V in a 100 mg L<sup>−1</sup> Cd<sup>2+</sup> solution, which is about 36.3 % higher than that of the symmetrical configuration NSTC-3//NSTC-3. Furthermore, 71 % of the initial removal capacity of the YP-50F//NSTC-3 system is retained after 7 cycles of charging and discharging. Characterizations of the cathode after the adsorption process indicate that the Cd<sup>2+</sup> is captured by both electrical-double-layer and pseudocapacitive mechanisms. Additionally, CdCO<sub>3</sub> precipitate is also responsible for Cd<sup>2+</sup> removal, which might be ascribed to the reaction of dissolved CO<sub>2</sub> in aqueous media with Cd<sup>2+</sup> under the electrified action. The high removal performance and excellent cycling stability are attributed to the tunability of the surface charge properties and the asymmetric configuration, which minimizes the co-ion expulsion and modulates potential distribution. This study provides a novel avenue to design biochar-based configurations for electrified water treatment.</div></div>","PeriodicalId":6964,"journal":{"name":"物理化学学报","volume":"41 3","pages":"Article 100023"},"PeriodicalIF":10.8,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143181307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-02DOI: 10.3866/PKU.WHXB202408007
Aoyu Huang , Jun Xu , Yu Huang , Gui Chu , Mao Wang , Lili Wang , Yongqi Sun , Zhen Jiang , Xiaobo Zhu
5 V-class LiNi0.5Mn1.5O4 (LNMO) cathode material is emerging as a promising cobalt-free alternative to meet the growing demand for affordable, high-performance lithium-ion batteries (LIBs). However, LNMO faces significant electrochemical challenges, particularly interfacial instability with commercial electrolytes due to its high operating potentials. This instability leads to the dissolution of transition metals and consequently electrode crosstalk, which severely deteriorates electrochemical performance. Surface coating is extensively investigated to reduce interfacial side reactions for enhanced cycling stability. Traditional methods typically require multiple steps, including dispersion, mixing, drying, and calcination, which can be time-consuming and complex. Additionally, the resulting ceramic coatings are often rigid and unevenly distributed due to lattice mismatches, potentially leading to poor interfacial contact and increased resistance. In this study, tetraethyl orthosilicate (TEOS) is proposed as a streamlined slurry additive to in situ form an ethoxy-functional polysiloxane (EPS) film on the surface of LNMO particles during electrode preparation. Post-mortem X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma (ICP) analyses reveal the crucial role of the EPS film in addressing interfacial instability issues. First, the EPS film serves as an artificial cathode-electrolyte interface (CEI) with a robust Si–O–Si bonding network, which is less vulnerable under high potentials. Second, the remaining ethoxy-functional groups in EPS scavenge HF by forming stable Si–F bonds, thereby suppressing the detrimental transition metal dissolution and crosstalk. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) further confirm the stability of the EPS film and the enhanced structural stability of the modified LNMO. Galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS) results demonstrate that EPS reduces the overall impedance and improves ion diffusion kinetics by forming stable electrode-electrolyte interfaces. As a result, compared to the baseline, the optimized LNMO cathode exhibits significantly improved cycling stability in both half cells (84.6 % vs. 51.4 % capacity retention after 1000 cycles) and full cells when paired with commercial graphite anodes (83.3 % vs. 53.4 % retention after 500 cycles). This strategy, further validated under elevated temperatures of 50 °C and in pouch-type cells, is expected to pave the way for the development of next-generation high-performance LIBs.
{"title":"Tailoring electrode-electrolyte interfaces via a simple slurry additive for stable high-voltage lithium-ion batteries","authors":"Aoyu Huang , Jun Xu , Yu Huang , Gui Chu , Mao Wang , Lili Wang , Yongqi Sun , Zhen Jiang , Xiaobo Zhu","doi":"10.3866/PKU.WHXB202408007","DOIUrl":"10.3866/PKU.WHXB202408007","url":null,"abstract":"<div><div>5 V-class LiNi<sub>0.5</sub>Mn<sub>1.5</sub>O<sub>4</sub> (LNMO) cathode material is emerging as a promising cobalt-free alternative to meet the growing demand for affordable, high-performance lithium-ion batteries (LIBs). However, LNMO faces significant electrochemical challenges, particularly interfacial instability with commercial electrolytes due to its high operating potentials. This instability leads to the dissolution of transition metals and consequently electrode crosstalk, which severely deteriorates electrochemical performance. Surface coating is extensively investigated to reduce interfacial side reactions for enhanced cycling stability. Traditional methods typically require multiple steps, including dispersion, mixing, drying, and calcination, which can be time-consuming and complex. Additionally, the resulting ceramic coatings are often rigid and unevenly distributed due to lattice mismatches, potentially leading to poor interfacial contact and increased resistance. In this study, tetraethyl orthosilicate (TEOS) is proposed as a streamlined slurry additive to <em>in situ</em> form an ethoxy-functional polysiloxane (EPS) film on the surface of LNMO particles during electrode preparation. Post-mortem X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma (ICP) analyses reveal the crucial role of the EPS film in addressing interfacial instability issues. First, the EPS film serves as an artificial cathode-electrolyte interface (CEI) with a robust Si–O–Si bonding network, which is less vulnerable under high potentials. Second, the remaining ethoxy-functional groups in EPS scavenge HF by forming stable Si–F bonds, thereby suppressing the detrimental transition metal dissolution and crosstalk. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) further confirm the stability of the EPS film and the enhanced structural stability of the modified LNMO. Galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS) results demonstrate that EPS reduces the overall impedance and improves ion diffusion kinetics by forming stable electrode-electrolyte interfaces. As a result, compared to the baseline, the optimized LNMO cathode exhibits significantly improved cycling stability in both half cells (84.6 % <em>vs.</em> 51.4 % capacity retention after 1000 cycles) and full cells when paired with commercial graphite anodes (83.3 % <em>vs.</em> 53.4 % retention after 500 cycles). This strategy, further validated under elevated temperatures of 50 °C and in pouch-type cells, is expected to pave the way for the development of next-generation high-performance LIBs.</div></div>","PeriodicalId":6964,"journal":{"name":"物理化学学报","volume":"41 4","pages":"Article 100037"},"PeriodicalIF":10.8,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143093637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-01DOI: 10.3866/PKU.WHXB202405016
Yuanyin Cui , Jinfeng Zhang , Hailiang Chu , Lixian Sun , Kai Dai
Semiconductor photocatalysis makes full use of solar energy, serving as a potent tactic to solve the worldwide energy deficit and safeguard the environment. Bismuth-based photocatalysts stand out among various photocatalysts as a significant area, due to their unique crystal structure, favorable mixed electron band structure, diverse composition, and huge potential for solar catalytic conversion. This document reviews the rational design of Bi-based photocatalysts for solar energy. Recent advancements in diverse Bi-based photocatalysts such as Layered Bi, Bismuth element, BiVO4, Bi2S2, and Bi2O3 are highlighted. Secondly, the synthesis strategies of Bi-based catalysts, including hydrothermal/solvothermal, chemical precipitation, and solid-state reaction, are summarized. Third, various structural regulation methods to improve the photocatalytic performance, including defect regulation, heteroatom doping, morphology, SPR effect utilization, and heterojunction construction, are systematically introduced. Additionally, a focus is given to the exclusive applications of Bi-based photocatalysts, including CO2 reduction, water decomposition, N2 fixation, NOx removal, H2O2 production, and selective organic synthesis, followed by an introduction of advanced in situ characterization techniques of the Bi-based photocatalysts. Ultimately, the forthcoming obstacles are underscored, and a future outlook for Bi-based photocatalysts is anticipated. This review aims to offer detailed instructions for comprehensively understanding and logically crafting effective bismuth-based photocatalysts, while also encouraging novel ideas and advances in energy and environmental fields, contributing to the goals of green chemistry and sustainable development.
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{"title":"Rational Design of Bismuth Based Photocatalysts for Solar Energy Conversion","authors":"Yuanyin Cui , Jinfeng Zhang , Hailiang Chu , Lixian Sun , Kai Dai","doi":"10.3866/PKU.WHXB202405016","DOIUrl":"10.3866/PKU.WHXB202405016","url":null,"abstract":"<div><div>Semiconductor photocatalysis makes full use of solar energy, serving as a potent tactic to solve the worldwide energy deficit and safeguard the environment. Bismuth-based photocatalysts stand out among various photocatalysts as a significant area, due to their unique crystal structure, favorable mixed electron band structure, diverse composition, and huge potential for solar catalytic conversion. This document reviews the rational design of Bi-based photocatalysts for solar energy. Recent advancements in diverse Bi-based photocatalysts such as Layered Bi, Bismuth element, BiVO<sub>4</sub>, Bi<sub>2</sub>S<sub>2</sub>, and Bi<sub>2</sub>O<sub>3</sub> are highlighted. Secondly, the synthesis strategies of Bi-based catalysts, including hydrothermal/solvothermal, chemical precipitation, and solid-state reaction, are summarized. Third, various structural regulation methods to improve the photocatalytic performance, including defect regulation, heteroatom doping, morphology, SPR effect utilization, and heterojunction construction, are systematically introduced. Additionally, a focus is given to the exclusive applications of Bi-based photocatalysts, including CO<sub>2</sub> reduction, water decomposition, N<sub>2</sub> fixation, NO<sub><em>x</em></sub> removal, H<sub>2</sub>O<sub>2</sub> production, and selective organic synthesis, followed by an introduction of advanced <em>in situ</em> characterization techniques of the Bi-based photocatalysts. Ultimately, the forthcoming obstacles are underscored, and a future outlook for Bi-based photocatalysts is anticipated. This review aims to offer detailed instructions for comprehensively understanding and logically crafting effective bismuth-based photocatalysts, while also encouraging novel ideas and advances in energy and environmental fields, contributing to the goals of green chemistry and sustainable development.</div><div><span><figure><span><img><ol><li><span><span>Download: <span>Download high-res image (122KB)</span></span></span></li><li><span><span>Download: <span>Download full-size image</span></span></span></li></ol></span></figure></span></div></div>","PeriodicalId":6964,"journal":{"name":"物理化学学报","volume":"40 12","pages":"Article 2405016"},"PeriodicalIF":10.8,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143128039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-01DOI: 10.3866/PKU.WHXB202407021
Yuejiao An , Wenxuan Liu , Yanfeng Zhang , Jianjun Zhang , Zhansheng Lu
S-scheme heterojunctions can preserve strong redox capacity on the basis of achieving spatial separation of photogenerated carriers. Therefore, a deep comprehension of the photoinduced charge transfer dynamics in S-scheme heterostructures is vital to enhancing photocatalytic properties. Herein, SnO2/BiOBr S-scheme heterojunctions with tight contact are fabricated with in situ hydrothermal method. The optimal SnO2/BiOBr exhibits excellent photocatalytic performance for CO2 reduction, with yields of CO and CH4 of 345.7 and 6.7 μmol∙g–1∙h–1, which are 5.6 and 3.7 times higher than those of the original BiOBr. The photoinduced charge transfer mechanism and dynamics of SnO2/BiOBr S-scheme heterostructure are characterized by in situ X-ray photoelectron spectrum (XPS) and femtosecond transient absorption spectroscopy (fs-TA). A new fitted lifetime of photogenerated carriers are observed, which could be attributed to interfacial electron transfer of S-scheme heterojunction, further illustrating an ultrafast transfer channel for photoelectrons from SnO2 conduction band to BiOBr valence band. As a result, the powerful reduced electrons in BiOBr conduction band and the powerful oxidation holes in SnO2 valence band are retained. This work provides profound comprehension of photoinduced charge transfer mechanism of S-scheme heterojunction.
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{"title":"Revealing Photoinduced Charge Transfer Mechanism of SnO2/BiOBr S-Scheme Heterostructure for CO2 Photoreduction","authors":"Yuejiao An , Wenxuan Liu , Yanfeng Zhang , Jianjun Zhang , Zhansheng Lu","doi":"10.3866/PKU.WHXB202407021","DOIUrl":"10.3866/PKU.WHXB202407021","url":null,"abstract":"<div><div>S-scheme heterojunctions can preserve strong redox capacity on the basis of achieving spatial separation of photogenerated carriers. Therefore, a deep comprehension of the photoinduced charge transfer dynamics in S-scheme heterostructures is vital to enhancing photocatalytic properties. Herein, SnO<sub>2</sub>/BiOBr S-scheme heterojunctions with tight contact are fabricated with <em>in situ</em> hydrothermal method. The optimal SnO<sub>2</sub>/BiOBr exhibits excellent photocatalytic performance for CO<sub>2</sub> reduction, with yields of CO and CH<sub>4</sub> of 345.7 and 6.7 μmol∙g<sup>–1</sup>∙h<sup>–1</sup>, which are 5.6 and 3.7 times higher than those of the original BiOBr. The photoinduced charge transfer mechanism and dynamics of SnO<sub>2</sub>/BiOBr S-scheme heterostructure are characterized by <em>in situ</em> X-ray photoelectron spectrum (XPS) and femtosecond transient absorption spectroscopy (fs-TA). A new fitted lifetime of photogenerated carriers are observed, which could be attributed to interfacial electron transfer of S-scheme heterojunction, further illustrating an ultrafast transfer channel for photoelectrons from SnO<sub>2</sub> conduction band to BiOBr valence band. As a result, the powerful reduced electrons in BiOBr conduction band and the powerful oxidation holes in SnO<sub>2</sub> valence band are retained. This work provides profound comprehension of photoinduced charge transfer mechanism of S-scheme heterojunction.</div><div><span><figure><span><img><ol><li><span><span>Download: <span>Download high-res image (85KB)</span></span></span></li><li><span><span>Download: <span>Download full-size image</span></span></span></li></ol></span></figure></span></div></div>","PeriodicalId":6964,"journal":{"name":"物理化学学报","volume":"40 12","pages":"Article 2407021"},"PeriodicalIF":10.8,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143128709","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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