Construction of A NiS/g-C3N4 Co-Catalyst-Based S-Scheme Heterojunction and Its Performance in Photocatalytic CO2 Reduction

NiS nanoparticles were chemically deposited on the surface of g-C3N4, in situ, followed by high-temperature calcination to prepare x-NiS/g-C3N4 co-catalyst-based S-scheme heterojunction photocatalysts. Due to the intrinsic charge accumulation preference on specific crystal planes of g-C3N4, NiS nanoparticles selectively deposited on its surface and formed a strong interfacial contact, thereby constructing an S-scheme heterojunction with co-catalytic functionality. This structure effectively suppressesd the recombination of electron–hole pairs in the valence band, significantly enhancing the separation efficiency of photogenerated charge carriers, and thereby improving performance in photocatalytic CO2 reduction. Compared with pure g-C3N4, the x-NiS/g-C3N4 photocatalysts exhibit superior CO2 reduction activity. Among them, the sample with 1.0% NiS loading showed the best performance, achieving CO and CH4 production rates of 27.34 μmol/g and 13.87 μmol/g, respectively, within 4 h.