Ir-based dectrocatalysts have been system- atically studied for a variety of applications, among which the electrocatalysis for oxygen evolution reaction （OER） is one of the most prominent. The investigation on surf...Ir-based dectrocatalysts have been system- atically studied for a variety of applications, among which the electrocatalysis for oxygen evolution reaction （OER） is one of the most prominent. The investigation on surface-micro- structure-sensitive catalytic activity in different pH media is of great significance for developing efficient electrocatalysts and corresponding mechanism research. Herein, shape-tunable Ir- Pd alloy nanocrystals, including nano-hollow-spheres （NHSs）, nanowires （NWs）, and nanotetrahedrons （NTs）, are synthe- sized via a facile one-pot solvothermal method, Electro- chemical studies show that the OER activity of the Ir-Pd alloy nanocatalysts exhibits surface-microstructure-sensitive en- hancement in acidic and alkaline media. Ir-Pd NWs and NTs show more than five times higher mass activity than com- mercial Ir/C catalyst at an overpotential of 0.25 V in acidic and alkaline media. Post-XPS analyses reveal that surface Ir（VI） oxide generated at surface defective sites of Ir-Pd nanocata- lysts is a possible key intermediate for OER. In acidic medium, the specific activity of Ir-Pd nanocatalysts has a positive cor- relation with the surface roughness of NWs 〉 NHSs 〉 NTs. However, the strong dissociation of surface Ir（VI） species （IrO42-） at surface defective sites is a possible obstacle for the formation of Ir（VI） oxide, which reverses the activity sequence for OER in alkaline medium.展开更多
基金supported by the National Natural Science Foundation of China (21573005, 21771009 and 21621061)the National Key Research and Development Program (2016YFB0701100)Beijing Natural Science Foundation (2162019)
文摘Ir-based dectrocatalysts have been system- atically studied for a variety of applications, among which the electrocatalysis for oxygen evolution reaction （OER） is one of the most prominent. The investigation on surface-micro- structure-sensitive catalytic activity in different pH media is of great significance for developing efficient electrocatalysts and corresponding mechanism research. Herein, shape-tunable Ir- Pd alloy nanocrystals, including nano-hollow-spheres （NHSs）, nanowires （NWs）, and nanotetrahedrons （NTs）, are synthe- sized via a facile one-pot solvothermal method, Electro- chemical studies show that the OER activity of the Ir-Pd alloy nanocatalysts exhibits surface-microstructure-sensitive en- hancement in acidic and alkaline media. Ir-Pd NWs and NTs show more than five times higher mass activity than com- mercial Ir/C catalyst at an overpotential of 0.25 V in acidic and alkaline media. Post-XPS analyses reveal that surface Ir（VI） oxide generated at surface defective sites of Ir-Pd nanocata- lysts is a possible key intermediate for OER. In acidic medium, the specific activity of Ir-Pd nanocatalysts has a positive cor- relation with the surface roughness of NWs 〉 NHSs 〉 NTs. However, the strong dissociation of surface Ir（VI） species （IrO42-） at surface defective sites is a possible obstacle for the formation of Ir（VI） oxide, which reverses the activity sequence for OER in alkaline medium.
