Unlocking the Potential of BiS-Derived Bi Nanoplates: Enhanced Catalytic Activity and Selectivity in Electrochemical and Photoelectrochemical CO Reduction to Formate.

Various electrocatalysts are extensively examined for their ability to selectively produce desired products by electrochemical CO reduction reaction (CORR). However, an efficient CORR electrocatalyst doesn't ensure an effective co-catalyst on the semiconductor surface for photoelectrochemical CORR. Herein, BiS nanorods are synthesized and electrochemically reduced to Bi nanoplates that adhere to the substrates for application in the electrochemical and photoelectrochemical CORR. Compared with commercial-Bi, the BiS-derived Bi (S-Bi) nanoplates on carbon paper exhibit superior electrocatalytic activity and selectivity for formate (HCOO) in the electrochemical CORR, achieving a Faradaic efficiency exceeding 93%, with minimal H production over a wide potential range. This highly selective S-Bi catalyst is being employed on the Si photocathode to investigate the behavior of electrocatalysts during photoelectrochemical CORR. The strong adhesion of the S-Bi nanoplates to the Si nanowire substrate and their unique catalytic properties afford exceptional activity and selectivity for HCOO under simulated solar irradiation. The selectivity observed in electrochemical CORR using the S-Bi catalyst correlates with that seen in the photoelectrochemical CORR system. Combined pulsed potential methods and theoretical analyses reveal stabilization of the OCHO* intermediate on the S-Bi catalyst under specific conditions, which is critical for developing efficient catalysts for CO-to-HCOO conversion.