Efficient methane production from photocatalytic CO2 reduction by InCu0.05Co0.05Ox: The synergistic effect of Co and Cu

• The co-doping of Cu and Co exhibits a synergistic effect in the In 2 O 3 catalyst. • The doping of Co can efficiently reduce the band gap of the In 2 O 3 catalyst. • The doping of Cu has improved the adsorption performance of the catalyst for CO 2 . • Cu Co co-doping synergistically modulates the band structures and CO 2 activation. Photocatalytic reduction of CO 2 to methane (CH 4 ) is a promising strategy to address CO 2 emissions and energy scarcity. However, low efficiency limits its practical application. This study presents a bimetallic co-doping strategy using Cu and Co to enhance the photocatalytic performance of the In 2 O 3 catalyst. The InCu 0.05 Co 0.05 O x (InCuCo) catalyst demonstrated a CH 4 yield of 22.3 µmol·g −1 ·h −1 , outperforming In 2 O 3 (8.8 µmol·g −1 ·h −1 ), InCu (14.5 µmol·g -1 ·h −1 ), and InCo (18.0 µmol·g -1 ·h −1 ). This remarkable improvement highlights the synergistic effects of Cu and Co in the In 2 O 3 catalyst. Characterizations and density functional theory (DFT) calculations revealed that Co doping narrows the bandgap of the catalyst, enhancing light utilization, while Cu adjusts the energy band positions and improves CO 2 adsorption. Consequently, the InCuCo catalyst significantly enhances the photocatalytic reduction of CO 2 –CH 4 , offering remarkable activity and stability. These results provide new insights into CO 2 photoreduction to CH 4 , facilitating further practical applications.