Non-noble-metal CuSe promotes charge separation and photocatalytic CO2 reduction on porous g-C3N4 nanosheets

Photocatalytic CO2 reduction based on g-C3N4 with inexpensive, efficient, stable, and suitable energy band structure, serve as a promising candidate for alleviating the greenhouse effect. However, g-C3N4 still suffers from low CO2 photoreduction performance owing to severe charge recombination and high surface reaction energy barriers. Herein, porous g-C3N4/CuSe (PCN/CS) Schottky heterojunctions were fabricated by loading nonprecious CS nanosheets on porous PCN nanosheets, contributing to a decreased the reaction energy barrier and elevated charge separation. The improved charge separation by Schottky heterojunction were unveiled by the transient photocurrents as well as photoluminescence (PL) spectra. The photogenerated electrons transfer from PCN to CS was demonstrated by density functional theory (DFT) calculations and XPS analysis. Meanwhile, CS lowers the energy berries and serves as an active site for CO2 reduction, thus accelerating the CO2 photoreduction processes. The experimental results manifest that the CO2 photoreduction efficiency of PCN/CS was significantly higher than that of pure PCN and CS. The efficiency of CO2 photoreduction to CO in the composite sample was 25.03 mu mol.g(-1).h(-1), which was 6.53 times and 2.45 times higher than that of pure CS and PCN, respectively. This work provides a new insight on the design of Schottky junctions by anchoring non-precious metal on PCN for ameliorated CO2 photoreduction performance.