Composition Tuned Electron Rearrangement of Transition-Metal-Based Compounds Promotes Hydrogen Generation

Efficient noble-metal-free electrocatalysts are criticallyimportantfor sustainable generation of green hydrogen. Though many advancedtransition-metal-based catalysts have been well developed, the composition-structure-performancerelationship is still arguable. Herein, we comprehensively investigatedthe catalytic performance of transition-metal-based compounds withtuned chemical compositions but similar atomic and microstructuresto disentangle the roles of chemical composition from the structuraleffects. Based on a series of characterizations, we found that theengineering of transition metal cations would lead to electron rearrangementand then improve the catalytic activity of the formed transition metaloxides (TMO) toward water oxidation. The intake of anions on the TMOsurface resulted in the change of surface charge, making them multifunctionalcatalysts for both urea oxidation and hydrogen evolution reactions.By using the prepared TMO and derived heterostructured a-TMO/c-TMSin the two-electrode system, the constructed TMO & PAR;a-TMO/c-TMSexhibited a much decreased potential for alkali hydrogen generationthan that of the noble-metal-based system (IrO2 & PAR;Pt).This work reveals the roles of cations and anions in transition-metal-basedmaterials for energy conversion reactions, which would shed lighton the design of novel and efficient catalysts by chemical compositiontuning.