Amorphous CoFeB nanosheets with plasmon-regulated dynamic active sites for electrocatalytic water oxidation

Exploring efficient and low-cost oxygen evolution reaction (OER) electrocatalysts is of crucial importance. Here, we report a surface plasmon resonance (SPR) engineering strategy to regulate surface reconstruction of CoFeB nanosheets by decorating plasmonic MoO2 nanospheres (MoO2/CoFeB), in which the SPR effect of MoO2 offers an additional acceleration for the conversion of inactive Co species to active cobalt oxyhydroxide on the CoFeB surface under visible light. Our results also indicate the real reactive surface for CoFeB is in the form of CoFeOOH with adsorbed BO2− that has positive effect. The MoO2/CoFeB shows superior OER performance with a low overpotential (209 mV at J=10 mA cm−2). However, such an accelerated reconstruction behavior would be self-terminated once the anodic voltage increases to thoroughly oxidize the MoO2 to high valence state (+6). This work inspires us to develop a rational strategy to improve the catalytic performance by properly regulating the surface reconstruction.