2D/2D g-C3N4/ZnxCd1-xS Van der Waals heterojunctions modulation: Interfacial chemical bond accelerating charge separation for enhanced photocatalytic CO2 reduction

The fabrication of Van der Waals (VDW) heterojunctions between two-dimensional materials has recently sparked the curiosity of researchers due to their compact interfaces, low energy barriers and efficient interfacial electron mobility efficiency. However, the relatively weak VDW interactions and VDW gap inhibits the migration of carriers across layers. Herein, we developed a novel 2D/2D ZnxCd1-xS/g-C3N4 catalysts for regulating VDW heterojunctions by the interface engineering. ZnxCd1-xS nanosheets are strongly coordinated with g-C3N4, and the compact VDW heterojunctions and Zn/Cd molar ratios modulation induces Cd-N bonds to modulate the electronic structure at the interface. Evidenced by the experimental and theoretical calculation analysis, the constructed interfacial Cd-N bonds could function as a novel electron transport bridge between Zn0.8Cd0.2S and g-C3N4, enabling the photogenerated electron-hole pairs to be efficiently migrated directionally across the interlayer potential barrier. Therefore, Zn0.8Cd0.2S/g-C3N4 exhibits the enhanced CO2 reduction performance that is 3.2 times better than that of pure g-C3N4 without the usage of co-catalysts or sacrificial agents. This work introduces an avenue to regulate Van der Waals heterojunctions and provides an efficient photocatalyst for green energy conversion.