Unveiling the active site of an electrocatalyst is fundamental for the development of efficient electrode material.For the two-electron water oxidation to produce H_(2)O_(2),competitive reactions,including four-and on...Unveiling the active site of an electrocatalyst is fundamental for the development of efficient electrode material.For the two-electron water oxidation to produce H_(2)O_(2),competitive reactions,including four-and one-electron water oxidation and surface reconstruction derived from the high-oxidative environment co-existed,leading to great challenges to identify the real active sites on the electrode.In this work,Ti/TiO_(2)-based electrodes calcined under air,nitrogen,or urea atmospheres were selected as electrocatalysts for two-electron water oxidation.Electrochemical analyses were applied to evaluate the catalytic activity and selectivity.The morphological and current change on the electrode surface were determined by scanning electrochemical microscopy,while the chemical and valence evolutions with depth distributions were tested by XPS combined with cluster argon ion sputtering.The results demonstrated that Ti/TiO_(2) nanotube arrays served as the support,while the functional groups of carbonyl groups and pyrrolic nitrogen derived from the co-pyrolysis with urea were the active sites for the H_(2)O_(2) production.This finding provided a new horizon to design efficient catalysts for H_(2)O_(2) production.展开更多
Zinc-air battery is one of the most promising next-generation energy conversion and storage systems.Green and low-cost catalysts with high oxygen reduction reaction(ORR)catalytic activity are desired to meet the requi...Zinc-air battery is one of the most promising next-generation energy conversion and storage systems.Green and low-cost catalysts with high oxygen reduction reaction(ORR)catalytic activity are desired to meet the requirements of Zinc-air batteries.Herein,poly-active centric Co3O4-CeO2/Co-N-C(ketjenblack carbon)catalysts were prepared by a facile method.The Co3O4 and CeO2 nanoparticles are uniformly anchored on the surface of Co and N doped carbon support.The half-wave potential of Co3O4-CeO2/Co-N-C in the rotating disk electrode testing is close to that of Pt/C.The Zn-air battery using Co3O4-CeO2/Co-N-C as the cathode catalyst can provide a high specific capacity of 728 mA h g^-1 at 20 mA cm^-2 and maintain a stable discharge voltage.The remarkable catalytic performance is mainly attributed to the synergistic effect among Co3O4,CeO2 and Co-N-C,the outstanding electrical conductivity and the large surface area.Benefitting from the high catalytic activity,environmental friendliness and the facile synthesis process,Co3O4-CeO2/Co-N-C catalyst lends itself well to a great prospect in the application of metalair batteries.展开更多
Room temperature ionic liquids （ILs） composed of cations and anions, as well as deep eutectic solvents （DESs） composed of hydrogen bond donors （HBDs） and hydrogen bond acceptors （HBAs）, are regarded as green s...Room temperature ionic liquids （ILs） composed of cations and anions, as well as deep eutectic solvents （DESs） composed of hydrogen bond donors （HBDs） and hydrogen bond acceptors （HBAs）, are regarded as green solvents due to their low volatility. They have been used widely for electrochemically driven reactions because they exhibit high conductivity and excellent elec- trochemical stability. However, no systematic investigations on the electrochemical potential windows （EPWs）, which could be used to characterize the electrochemical stability, have been reported. In this regard, the EPWs of 33 ILs and 23 DESs have been studied utilizing cyclic voltammetry （CV） method and the effects of structural factors （cations and anions of ILs, and HBDs and HBAs of DESs） and external factors （electrode, water content） on the EPWs have been comprehensively investi- gated. The electrochemical stability of selected 1Ls comprising five traditional cations, namely imidazolium, pyridinium, pyr- rolidinium, piperidinium and ammonium and 13 kinds of versatile anions was studied. The results show that for ILs, both cati- on and anion play an important role on the reductive and oxidative potential limit. For a same IL at different working electrode, for example, glassy carbon （GC）, gold （Au） and platinum （Pt） electrode, the largest potential window is almost observed on the GC working electrode. The investigations on the EPWs of choline chloride （ChCl）, choline bromide （ChBr）, choline iodide （ChI）, and methyl urea based DESs show that the DES composed of ChCl and methyl urea has the largest potential window. This work may aid the selection of ILs or DESs for use as a direct electrolyte or a solvent in electrochemical applications.展开更多
基金Project(2021JJ30792) supported by the Natural Science Foundation of Hunan Province,ChinaProject(52170031) supported by the National Natural Science Foundation of ChinaProject supported by the Fundamental Research Funds for the Central Universities,China。
文摘Unveiling the active site of an electrocatalyst is fundamental for the development of efficient electrode material.For the two-electron water oxidation to produce H_(2)O_(2),competitive reactions,including four-and one-electron water oxidation and surface reconstruction derived from the high-oxidative environment co-existed,leading to great challenges to identify the real active sites on the electrode.In this work,Ti/TiO_(2)-based electrodes calcined under air,nitrogen,or urea atmospheres were selected as electrocatalysts for two-electron water oxidation.Electrochemical analyses were applied to evaluate the catalytic activity and selectivity.The morphological and current change on the electrode surface were determined by scanning electrochemical microscopy,while the chemical and valence evolutions with depth distributions were tested by XPS combined with cluster argon ion sputtering.The results demonstrated that Ti/TiO_(2) nanotube arrays served as the support,while the functional groups of carbonyl groups and pyrrolic nitrogen derived from the co-pyrolysis with urea were the active sites for the H_(2)O_(2) production.This finding provided a new horizon to design efficient catalysts for H_(2)O_(2) production.
基金financial support from the Department of Science and Technology of Guangdong Province,China(2019A050510043)Shenzhen Science and Technology Innovation Commission(JCYJ20180507183818040)。
文摘Zinc-air battery is one of the most promising next-generation energy conversion and storage systems.Green and low-cost catalysts with high oxygen reduction reaction(ORR)catalytic activity are desired to meet the requirements of Zinc-air batteries.Herein,poly-active centric Co3O4-CeO2/Co-N-C(ketjenblack carbon)catalysts were prepared by a facile method.The Co3O4 and CeO2 nanoparticles are uniformly anchored on the surface of Co and N doped carbon support.The half-wave potential of Co3O4-CeO2/Co-N-C in the rotating disk electrode testing is close to that of Pt/C.The Zn-air battery using Co3O4-CeO2/Co-N-C as the cathode catalyst can provide a high specific capacity of 728 mA h g^-1 at 20 mA cm^-2 and maintain a stable discharge voltage.The remarkable catalytic performance is mainly attributed to the synergistic effect among Co3O4,CeO2 and Co-N-C,the outstanding electrical conductivity and the large surface area.Benefitting from the high catalytic activity,environmental friendliness and the facile synthesis process,Co3O4-CeO2/Co-N-C catalyst lends itself well to a great prospect in the application of metalair batteries.
基金supported by the National Natural Science Foundation of China (21173267, 21473252)
文摘Room temperature ionic liquids （ILs） composed of cations and anions, as well as deep eutectic solvents （DESs） composed of hydrogen bond donors （HBDs） and hydrogen bond acceptors （HBAs）, are regarded as green solvents due to their low volatility. They have been used widely for electrochemically driven reactions because they exhibit high conductivity and excellent elec- trochemical stability. However, no systematic investigations on the electrochemical potential windows （EPWs）, which could be used to characterize the electrochemical stability, have been reported. In this regard, the EPWs of 33 ILs and 23 DESs have been studied utilizing cyclic voltammetry （CV） method and the effects of structural factors （cations and anions of ILs, and HBDs and HBAs of DESs） and external factors （electrode, water content） on the EPWs have been comprehensively investi- gated. The electrochemical stability of selected 1Ls comprising five traditional cations, namely imidazolium, pyridinium, pyr- rolidinium, piperidinium and ammonium and 13 kinds of versatile anions was studied. The results show that for ILs, both cati- on and anion play an important role on the reductive and oxidative potential limit. For a same IL at different working electrode, for example, glassy carbon （GC）, gold （Au） and platinum （Pt） electrode, the largest potential window is almost observed on the GC working electrode. The investigations on the EPWs of choline chloride （ChCl）, choline bromide （ChBr）, choline iodide （ChI）, and methyl urea based DESs show that the DES composed of ChCl and methyl urea has the largest potential window. This work may aid the selection of ILs or DESs for use as a direct electrolyte or a solvent in electrochemical applications.
