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Full-Text Articles in Physical Sciences and Mathematics

Electrochemical Impedance Spectroscopy For Electrocatalytic Interfaces And Reactions: Classics Never Die, Huang Jun Feb 2020

Electrochemical Impedance Spectroscopy For Electrocatalytic Interfaces And Reactions: Classics Never Die, Huang Jun

Journal of Electrochemistry

This review article recapitulates electrochemical impedance spectroscopy (EIS) studies in the field of electrocatalysis. The history of this specialized field, ranging from the beginning of the twentieth century to now, is outlined. We then chronicle milestones of the impedance theory. Special emphases are put on the Dolin-Ershler model, the prevailing model for analyzing adsorption impedance data. Afterwards, we narrow into a very specific and fundamental topic, the double-layer capacitance at platinum (Pt) single crystals. We discuss the challenges in experimentation and theoretical understanding thereof. We cast doubts into the validity of using the Dolin-Ershler model to obtain the double-layer capacitance …


Recent Progress In The Mechanistic Understanding Of Co2 Reduction On Copper, Matthew M Sartin, Wei Chen, Fan He, Yan-Xia Chen Feb 2020

Recent Progress In The Mechanistic Understanding Of Co2 Reduction On Copper, Matthew M Sartin, Wei Chen, Fan He, Yan-Xia Chen

Journal of Electrochemistry

In this review, we present the major developments in the understanding of the mechanisms of the electrochemical reduction of CO2 from a historical perspective. Most of the work discussed in this review was carried out at copper electrodes, as this is the only material at which hydrocarbons are produced in reasonable quantities. The emphasis focuses on the differentiation of mechanisms for the generation of C1 and C2 products as well as factors and methods for controlling the product selectivity of CO2 reduction. We have highlighted ambiguities, assumptions, and important methodologies, such as differential electrochemical mass spectrometry and electrochemical …


Challenges In The Activity And Stability Of Pt-Based Catalysts Toward Orr, Tuo Zhao, Er-Gui Luo, Xian Wang, Jun-Jie Ge, Chang-Peng Liu, Wei Xing Feb 2020

Challenges In The Activity And Stability Of Pt-Based Catalysts Toward Orr, Tuo Zhao, Er-Gui Luo, Xian Wang, Jun-Jie Ge, Chang-Peng Liu, Wei Xing

Journal of Electrochemistry

The development of highly efficient oxygen reduction reaction (ORR) catalysts is the key to the commercialization of fuel cells, where the sluggish ORR reaction rate needs to be overcome by adjusting the intermediates adsorption energies on the catalytic surfaces. To-date, platinum (Pt)-based materials are the-state-of-the-art catalysts in terms of both activity and stability in ORR, making them the preferred choice for commercial applications. However, the high cost of Pt-based catalysts limits their widespread use, leading to massive effects paid in reducing Pt loading, improving catalyst activity and stability. This article illustrates the challenges in the ORR reaction and introduces the …


Effect Of Nitrogen Content In Catalyst Precursor On Activity Of Fen/C Catalyst For Oxygen Reduction Reaction, Zhi Yang, Ya-Yun Shen, E Zhou, Cheng-Ling Wei, Hao-Li Qin, Juan Tian Feb 2020

Effect Of Nitrogen Content In Catalyst Precursor On Activity Of Fen/C Catalyst For Oxygen Reduction Reaction, Zhi Yang, Ya-Yun Shen, E Zhou, Cheng-Ling Wei, Hao-Li Qin, Juan Tian

Journal of Electrochemistry

Non-noble metal catalysts with high activity and low cost have attracted increasing interest as potential catalysts for oxygen reduction reaction (ORR) to replace Pt-based catalysts. In this paper, the effect of nitrogen content in catalyst precursor on ORR activity of FeN/C catalyst was investigated by X-ray diffraction (XRD), Brunauer-Emmet-Teller (BET) surface area and pore size distribution measurements, transmission electron microscope (TEM), thermogravimetric analysis (TGA), and rotating disk electrode (RDE) techniques. The results show that the most active catalyst was obtained by pyrolysis in argon at 1050 °C with a catalyst precursor containing 20wt% 1,10-phenanthroline, 1wt% Fe and Black Pearl 2000. …


Structures And Electrochemical Properties Of Sn-Cl Co-Doped Li2Mno3 As Positive Materials For Lithium Ion Batteries, Fei Wang, Huan-Huan Zhai, Du-Dan Wang, Yu-Peng Li, Kang-Hua Chen Feb 2020

Structures And Electrochemical Properties Of Sn-Cl Co-Doped Li2Mno3 As Positive Materials For Lithium Ion Batteries, Fei Wang, Huan-Huan Zhai, Du-Dan Wang, Yu-Peng Li, Kang-Hua Chen

Journal of Electrochemistry

Positive material Li2MnO3 shows the highest ratio of lithium to manganese among lithium-rich materials and exhibites the theoretical capacity up to 458 mAh·g -1, making it one of the most promising cathode materials. However, this material has the intrinsic low electrical conductivity and poor cycle stability. In this paper, Li2MnO3, the lithium-rich positive material, was prepared by sol-gel method using acetate as raw material and citric acid as a complexing agent. By using SnC2O4 as a tin source, Sn 4+ instead of Mn 4+ was introduced to obtain the materials …


Lithium Storage Performance Of High Capacity Material Si@CPzs In Lithium Ion Batteries, Qing-Nuan Zhang, Fang-Fang Zhang, Hong-Xia Li, Bing-Jun Yang, Xiao-Cheng Li, Juan Yang Feb 2020

Lithium Storage Performance Of High Capacity Material Si@CPzs In Lithium Ion Batteries, Qing-Nuan Zhang, Fang-Fang Zhang, Hong-Xia Li, Bing-Jun Yang, Xiao-Cheng Li, Juan Yang

Journal of Electrochemistry

Carbon layers with different thicknesses were introduced into the surfaces of silicon (Si) nanoparticles by sol-gel method using poly (cyclotriphosphazene-co-4, 4'-sulfonyldiphenol) as the carbon source. Technologies of X-ray diffraction, thermo-gravimetric analysis, Brunauer-Emmett-Teller and transmission electron microscopy were employed to analyze the structures and components of the as-prepared Si@CPZS composites. Electrochemical performance of Si@CPZS with different carbon thicknesses was studied. The results showed that Si@CPZS with carbon thickness of 10 nm possessed the best performance. Its capacity remained 940 mAh·g -1 after 290 cycles under 500 mA·g -1. As the addictive, the graphite-based anode contained 30% of Si@C …


Electrochemical Preparations And Applications Of Nano-Catalysts With High-Index Facets, Chi Xiao, Na Tian, Zhi-You Zhou, Shi-Gang Sun Feb 2020

Electrochemical Preparations And Applications Of Nano-Catalysts With High-Index Facets, Chi Xiao, Na Tian, Zhi-You Zhou, Shi-Gang Sun

Journal of Electrochemistry

The performance of catalysts highly depends on their surface structure and composition. Nanocrystals bounded by high-index facets usually exhibit high catalytic activity due to their high-density low-coordinated step atoms with high reactivity. In this paper, we have reviewed the preparations of noble metals (e.g., Pt, Pd and Rh) nanocatalysts with high-index facets by electrochemical square-wave potential method developed in our group. The square-wave potential method includes a nucleation procedure to generate nuclei, followed by a square-wave potential procedure for a certain period of time for the growth of nuclei into nanocrystals. The formation mechanism of high-index facets is also discussed. …


Research Progresses In Ni-Co-Mn/Al Ternary Concentration Gradient Cathode Materials For Li-Ion Batteries, Chun-Fang Zhang, Wen-Gao Zhao, Shi-Yao Zheng, Yi-Xiao Li, Zheng-Liang Gong, Zhong-Ru Zhang, Yong Yang Feb 2020

Research Progresses In Ni-Co-Mn/Al Ternary Concentration Gradient Cathode Materials For Li-Ion Batteries, Chun-Fang Zhang, Wen-Gao Zhao, Shi-Yao Zheng, Yi-Xiao Li, Zheng-Liang Gong, Zhong-Ru Zhang, Yong Yang

Journal of Electrochemistry

Nickel-rich ternary materials with large reversible capacity as well as high operating voltage are considered as the most promising candidate for next generation lithium-ion batteries (LIBs). However, the inferior cycle stability and thermal stability have limited their widely commercial applications. Concentration gradient design of Ni-Co-Mn/Al ternary concentration gradient materials have been extensively studied in the past decade, which can ensure high cycle capacity while maintaining excellent cycle stability. In this paper, the latest research progresses in Ni-Co-Mn/Al ternary concentration gradient materials for LIBs are reviewed. Firstly, we summarize the different synthesis methods of ternary concentration-gradient materials, especially focusing on the …


Preparation And Electrocatalytic Performance Of Nico2O4/Ni Foam For Hydrogen Peroxide Electrooxidation, Wei-Wei Chen, Fei-Fan Zhang, Jia-Liang Du, Yi Wang, Chun-Lin Zhao, Kai Zhu, Dian-Xue Cao, Gui-Ling Wang Feb 2020

Preparation And Electrocatalytic Performance Of Nico2O4/Ni Foam For Hydrogen Peroxide Electrooxidation, Wei-Wei Chen, Fei-Fan Zhang, Jia-Liang Du, Yi Wang, Chun-Lin Zhao, Kai Zhu, Dian-Xue Cao, Gui-Ling Wang

Journal of Electrochemistry

The electrodes of Ni foam supported NiCo2O4 nanowires were prepared by hydrothermal method, followed by a thermal treatment in air, and were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that the NiCo2O4 nanowires had a diameter of about 50 nm with a length up to 3 ~ 5 μm. The catalytic performances of the Ni foam supported NiCo2O4 nanowires for H2O2 electrooxidation were studied by cyclic voltammetry and chronoamperometry. The results show that the Ni foam supported NiCo …


In-Situ Raman Spectroscopic Study Of Electrochemical Reactions At Single Crystal Surfaces, Min Su, Jin-Chao Dong, Jian-Feng Li Feb 2020

In-Situ Raman Spectroscopic Study Of Electrochemical Reactions At Single Crystal Surfaces, Min Su, Jin-Chao Dong, Jian-Feng Li

Journal of Electrochemistry

Since the 1970s, in-situ spectroscopy (Raman, infrared, etc.) has been used to systematically study the electrochemical interfacial reactions which can provide more information about surface reactions and reveal the mechanisms from microscopic view due to its excellent surface sensitivity and energy resolution. With the development of nano-technology, surface-enhanced Raman scattering effect spectroscopy has made rapid progress. Recently, the emergence of SHINERS provides a good in-situ spectroscopic technique for the study of catalytic reactions on single crystal model electrodes with deterministic surface structure. In this paper, we have summarized the application of SHINERS in the study of …


Preparations Of Nickel-Iron Hydroxide/Sulfide And Their Electrocatalytic Performances For Overall Water Splitting, Hang-Shuo Lu, Xiao-Bo He, Feng-Xiang Yin, Guo-Ru Li Feb 2020

Preparations Of Nickel-Iron Hydroxide/Sulfide And Their Electrocatalytic Performances For Overall Water Splitting, Hang-Shuo Lu, Xiao-Bo He, Feng-Xiang Yin, Guo-Ru Li

Journal of Electrochemistry

The Ni-Fe/Ti oxygen evolution electrode was prepared by electrodeposition on a titanium mesh substrate. Then, the as prepared Ni-Fe/Ti electrode was used to derive the Ni-Fe-S/Ti hydrogen evolution electrode through solid phase sulfuration. The effects of the molar ratio of Ni 2+ to Fe 3+ in the electrolyte and the amount of thiourea on the structures and electrochemical performances of Ni-Fe/Ti and Ni-Fe-S/Ti electrodes were investigated. The results show that the oxygen evolution performance of Ni-Fe/Ti electrode was first increased and then decreased with the increase of nickel ion content in the electrolyte. The Ni9Fe1/Ti electrode exhibited the best oxygen …


Atomic Force Microscopic Characterization Of Solid Electrolyte Interphase In Lithium Ion Batteries, Qing-Yu Dong, Yan-Li Chu, Yan-Bin Shen, Li-Wei Chen Feb 2020

Atomic Force Microscopic Characterization Of Solid Electrolyte Interphase In Lithium Ion Batteries, Qing-Yu Dong, Yan-Li Chu, Yan-Bin Shen, Li-Wei Chen

Journal of Electrochemistry

In recent years, the rapid growing in the electric vehicle market has raised higher requirement on the lithium-ion batteries (LIBs) performance towards energy density and safety. However, considering the successful development of LIBs techniques in the past 30 years, there is little room left for improving the LIBs performance on the aspects related to the electrode materials, battery structure design and production processes. It is important to pursue more comprehensive fundamental understanding in the entire system and working principle of LIBs. Solid electrolyte interphase (SEI), existing between the electrode material and the electrolyte, has been proved to be an important …