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

CO2, 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 (Cu2O/β-Bi2O3) at 300 °C with the main exposure of β-Bi2O3 (2 0 1) planes shows the beautiful micro-flower morphology with numerous petals in thickness around 20 ∼ 40 nm. Therefore, the Cu2O/β-Bi2O3 heterostructure with active edge sites can electrochemically convert CO2 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 Cu2O/β-Bi2O3 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 CO2 reduction performance is due to the fast charge-transfer process between Cu2O and β-Bi2O3. This study may provide a new route to directly synthesize the photoactive electrocatalysts with more edge sites and heterojunction for promoting electrochemical CO2 reduction performance with the assistance of light field.