Yifan Wang, Fengyu Tian, Jiayu Liang, Xuemin Yan
Photocatalytic CO 2 conversion is regarded as an effective strategy to tackle energy-related and ecological issues by generating sustainable fuels. Herein, we develop CoNi 2 S 4 /Zn 0.8 Cd 0.2 S S-scheme heterojunctions constructed via an in situ sulfurization approach. Through combined density functional theory calculations and experimental investigations, we demonstrate that electron transfer from CoNi 2 S 4 to Zn 0.8 Cd 0.2 S establishes an internal electric field (IEF) directed from CoNi 2 S 4 to Zn 0.8 Cd 0.2 S. Both in situ X-ray photoelectron spectroscopy and Kelvin probe force microscopy analyses demonstrate that the IEF promotes the migration of photoinduced electrons via interfacial Ni–S–Zn bonds, thereby verifying the establishment of an S-scheme heterojunction that markedly improves charge separation efficiency. The optimized heterojunction exhibits exceptional CO 2 photoreduction performance, accomplishing a CO yield rate of 3.60 μmol g –1 h –1, which is 9.0 and 4.9 times higher than those of the original state CoNi 2 S 4 (0.40 μmol g –1 h –1 ) and Zn 0.8 Cd 0.2 S (0.73 μmol g –1 h –1 ), respectively. This study provides critical insights for designing high-performance metal sulfide-based S-scheme heterojunctions toward efficient CO 2 photoreduction.