Rational Construction of Z‐Scheme CuInS2/Au/g‐C3N4 Heterostructure: Experimental Results and Theoretical Calculation

Abstract Two dimensional (2D) heterojunction based on g‐C 3 N 4 and CuInS 2 (CIS) nanosheets has been successfully constructed with the assistance of biomolecules L‐cysteine. We demonstrated that a typical p–n junction charges transfer mode of CIS/PCN (protonated g‐C 3 N 4 ) can be switched to Z‐scheme transfer mode through the integration of Au by weakening the role of built‐in electric field. The morphology of CIS/Au/PCN can be well adjusted through the formation of Au−S covalent bond and the electrostatic adsorption between Au and PCN during the hydrothermal process. Furthermore, the intimate interface contact inside CIS/Au/PCN heterojunction was indeed constructed, which may promote the charges separation and transfer process at the interface as evidenced by ESR spectra and time‐resolved PL spectra. Under visible light illumination, the CIS/Au/PCN exhibited an enhanced CO (19.46 μmol/g) and CH 4 (1.18 μmol/g) yield in CO 2 reduction, which was about 5.04 times and 2.03 times higher than pure PCN. The composite heterojunction also showed excellent photocatalytic activity for tetracycline degradation with a 87 % degradation efficiency in 1 hour, which was 2.07 times higher than pure PCN. The experimental and theoretical calculation results demonstrated that an all‐solid‐state Z‐scheme heterojunction was formed in the CIS/Au/PCN system, which was different from the typical p–n junction charges transfer mechanism in CIS/PCN.