Boosting the electrochemical CO2 reduction performance by Cu2O/β-Bi2O3 bimetallic heterojunction with the assistance of light

CO 2 , as one of the greenhouse gases, actually represents a cheap and abundant C1 fuel to produce fuels and chemical stocks. Herein, inspired by photocatalysis and electrocatalysis, we have successfully synthesized a series of copper and bismuth oxides with heterostructure by a first co-electrodeposition method and then by thermal treatment at different temperatures. The bimetallic oxide (Cu 2 O/β-Bi 2 O 3 ) at 300 °C with the main exposure of β-Bi 2 O 3 (2   0   1) planes shows the beautiful micro-flower morphology with numerous petals in thickness around 20 ∼ 40 nm. Therefore, the Cu 2 O/β-Bi 2 O 3 heterostructure with active edge sites can electrochemically convert CO 2 into formate with a promising Faradaic efficiency (96.3 %) and current density (40.4 mA cm −2 ) at − 0.97 V vs. RHE. Specifically, the current density of Cu 2 O/β-Bi 2 O 3 bimetallic catalyst can be largely enhanced to 48.5 mA cm −2 at − 0.92 V vs. RHE with the assistance of light compared to the 30.1 mA cm −2 without light. The production rate of formate with the assistance of light can also be increased to 705.1 μmol h −1 cm −2 , superior to that of 536.4 μmol h −1 cm −2 without light. Such an excellent photo-assisted electrochemical CO 2 reduction performance is due to the fast charge-transfer process between Cu 2 O and β-Bi 2 O 3 . This study may provide a new route to directly synthesize the photoactive electrocatalysts with more edge sites and heterojunction for promoting electrochemical CO 2 reduction performance with the assistance of light field.