Bi catalysts supported on GaN nanowires toward efficient photoelectrochemical CO2 reduction

Abstract

Photoelectrodes combined with semiconductors and cocatalysts have been extensively investigated for photoelectrochemical reduction of CO₂ gas to chemicals and fuels. However, little attention has been paid to the electronic interaction between semiconductor photoelectrodes and cocatalysts, which is critical for controlling the CO₂ reduction reaction. Here, we have discovered that the unique electronic interaction at the interface between bismuth nanoparticles (Bi NPs) and gallium nitride nanowires (GaN NWs) can significantly boost the catalytic activity for the CO₂ reduction reaction on a silicon photocathode. Theoretical calculations suggest that the binary system consisting of Bi and GaN favors CO₂ conversion to HCOOH and enhances electron transfer from GaN NWs to Bi NPs. The optimized Bi/GaN/Si photocathode results in a superior faradaic efficiency of HCOOH (FE_HCOOH) of ∼98% at −0.3 V_RHE under 1-sun illumination.