Enhanced photoelectrocatalytic CO2 reduction to CO via structure-induced carrier separation in coral-like CuBi2O4-Bi2O3

Significant carrier recombination has severely limited the development of the most potential photoelectrocatalytic CO 2 reduction reaction (PEC-CO 2 RR). Herein, coral-like CuBi 2 O 4 -Bi 2 O 3 photocathodes are prepared using the strategy of the construction of heterojunction to improve the efficiency of carrier separation. As expected, its faradic efficiency of CO (FE CO ) at the lower potential (0.1 V vs. RHE) is 86.03 %, which is about 1.49 times higher than that of the original CuBi 2 O 4 film. The increased catalytic activity of CuBi 2 O 4 -Bi 2 O 3 can be attributed to the high surface area of the distinctive coral-like structure of Bi 2 O 3 , which enhances light absorption efficiency. Additionally, the higher degree of band bending in CuBi 2 O 4 -Bi 2 O 3 and the built-in electric field can speed up the transport rate of electrons, slow down the recombination of photogenerated electrons with holes and extend the lifetime of photogenerated electrons, allowing electrons to continuously participate in the reaction. This study proposes a novel strategy to optimize the efficiency of photoelectrocatalytic CO 2 reduction by CuBi 2 O 4 -based photocathodes.