Highly efficient photocatalytic conversion of CO2 into CH4 over Cu single atom promoted heterojunction: The effect of uplifted d-band center

Photoreduction of CO2 to solar fuels has caused great interest, but suffers from low catalytic efficiency and poor selectivity. Herein, we designed a S-scheme heterojunction (Cu-TiO2/WO3) with Cu single atom to significantly boost the photoreduction of CO2. Notably, the developed Cu-TiO2/WO3 achieved the solar-driven conversion of CO2 to CH4 with an evolution rate of 98.69 µmol g−1 h−1, and the electron selectivity of CH4 reached 88.5%. The yield was much higher than those of pristine WO3, TiO2/WO3 and Cu-TiO2 samples. Experimental and theoretical analysis suggested that the S-scheme heterojunction accelerated charge migration and inhibited the recombination of electron-hole pairs. Importantly, the charge separation effect of the heterojunction meliorated the position of the d-band. The uplifted d-band centers of Cu and Ti on Cu-TiO2/WO3 not only improved the electron interaction between Cu single atoms and substrate-TiO2, accelerated the adsorption and activation of CO2 on the active sites of Cu single atom, but also optimized the Gibbs free energies of CH4 formation pathway, leading to excellent selectivity toward CH4. This work provides new insights into the design of photocatalyst systems with high photocatalytic performance.