Elucidating the structure-activity relationship in electrocatalysis is of fundamental interest for electrochemical energy conversion and storage.However,the heterogeneity in the surface structure of electrocatalysts,i...Elucidating the structure-activity relationship in electrocatalysis is of fundamental interest for electrochemical energy conversion and storage.However,the heterogeneity in the surface structure of electrocatalysts,including the presence of various facets,poses an analytical challenge in revealing the true structure-activity relationship because the activity is conventionally measured on ensemble,resulting in an averaged activity that cannot be unequivocally associated with a single structural motif.Scanning electrochemical cell microscopy(SECCM)[1]combined with colocalized electron backscatter diffraction(EBSD)offers a direct way to reveal the correlative local electrochemical and structural information.Herein,we measured the hydrogen evolution reaction(HER)activity on Ag and its dependence on the crystal orientation.From the combined EBSD and SECCM mapping,it is found that Ag grains closer to{111}show a higher exchange current density,while those closer to{110}show a lower Tafel slope.The Tafel slope is also found to decrease with the step density increase.The ability to measure the electrocatalytic activity under a high mass-transfer rate allows us to reveal the activity difference at a high current density(up to 200 mA/cm^(2)).The approach reported here can be expanded to other systems to reveal the nature of active sites of electrocatalysis.展开更多
A nanoplatelet-like spinel metal oxide grain-decorated MXene composite was successfully synthesized via a hydrothermal reaction.The prepared MXene/Co_(3)O_(4)and MXene/Fe_(3)O_(4)nanocomposites possessed higher porosi...A nanoplatelet-like spinel metal oxide grain-decorated MXene composite was successfully synthesized via a hydrothermal reaction.The prepared MXene/Co_(3)O_(4)and MXene/Fe_(3)O_(4)nanocomposites possessed higher porosity than their pristine counterparts,realizing outstanding bifunctional electrocatalytic activity for hydrogen and oxygen evolution kinetics in alkaline media and requiring relatively low overpotentials of 52 and 6_(3)mV and 270 and_(3)10 mV vs.展开更多
基金sponsored by the Defense Advanced Research Project Agency (DARPA) and the Army Research Office and was accomplished under Grant Number W911NF-20-1-0304
文摘Elucidating the structure-activity relationship in electrocatalysis is of fundamental interest for electrochemical energy conversion and storage.However,the heterogeneity in the surface structure of electrocatalysts,including the presence of various facets,poses an analytical challenge in revealing the true structure-activity relationship because the activity is conventionally measured on ensemble,resulting in an averaged activity that cannot be unequivocally associated with a single structural motif.Scanning electrochemical cell microscopy(SECCM)[1]combined with colocalized electron backscatter diffraction(EBSD)offers a direct way to reveal the correlative local electrochemical and structural information.Herein,we measured the hydrogen evolution reaction(HER)activity on Ag and its dependence on the crystal orientation.From the combined EBSD and SECCM mapping,it is found that Ag grains closer to{111}show a higher exchange current density,while those closer to{110}show a lower Tafel slope.The Tafel slope is also found to decrease with the step density increase.The ability to measure the electrocatalytic activity under a high mass-transfer rate allows us to reveal the activity difference at a high current density(up to 200 mA/cm^(2)).The approach reported here can be expanded to other systems to reveal the nature of active sites of electrocatalysis.
基金supported by the research program of Dongguk University(No.S-2022-G0001-00016).
文摘A nanoplatelet-like spinel metal oxide grain-decorated MXene composite was successfully synthesized via a hydrothermal reaction.The prepared MXene/Co_(3)O_(4)and MXene/Fe_(3)O_(4)nanocomposites possessed higher porosity than their pristine counterparts,realizing outstanding bifunctional electrocatalytic activity for hydrogen and oxygen evolution kinetics in alkaline media and requiring relatively low overpotentials of 52 and 6_(3)mV and 270 and_(3)10 mV vs.
