Construction of 2D/3D g-C 3 N 4 /ZnIn 2 S 4 Heterojunction for Efficient Photocatalytic Reduction of CO 2 under Visible Light

A 2D/3D g-C 3 N 4 /ZnIn 2 S 4 heterojunction photocatalyst was constructed by a one-step hydrothermal method combined with a calcination process. This composite not only can use its heterostructure to improve the migration and separation of photogenerated electron–holes but also has stronger visible light utilization efficiency and CO 2 adsorption capacity, thereby improving the severe charge recombination of g-C 3 N 4 and ZnIn 2 S 4 monomers. The g-C 3 N 4 /ZnIn 2 S 4 heterojunction exhibits outstanding performance in CO 2 photoreduction. A maximum CO production of 40 wt % g-C 3 N 4 /ZnIn 2 S 4 composite can reach 82.26 μmol·g –1, which is 10.1 and 2.8 times as high as those of the g-C 3 N 4 and ZnIn 2 S 4 monomers, respectively. The heterojunction fabrication process and electronic changes were analyzed with respect to both experimental and theoretical aspects by means of photoelectrochemical measurements and density functional theory (DFT). Finally, we propose a feasible mechanism for the photocatalytic reduction of CO 2 on the g-C 3 N 4 /ZnIn 2 S 4 composite. This work could help to understand the structure regulation of carbon nitride-based materials and provides a certain guidance for the development of novel efficient and green heterojunction catalysts.