Interfacial chemical bond modulated Z-scheme mechanism in In2−xS3/Cd1+xIn2−xS4 heterojunction for enhanced photocatalytic CO2 reduction and wastewater treatment

Abstract

An interfacial CdS bond modulated hierarchical Z-scheme heterostructure composed by indium vacancies-rich In2-xS3 and Cd-rich Cd1+xIn2-xS4 (In2-xS3/Cd1+xIn2-xS4) is rationally designed and fabricated by using MIL-68 (In) as precursor and template, and used for efficient photocatalytic wastewater treatment and CO2 reduction. The in-situ ion-exchange derived CdS bond at the heterointerface induced the Z-scheme charge transfer mechanism in hierarchical In2-xS3/Cd1+xIn2-xS4 photocatalyst, which is verified by the X-ray photoelectron spectroscopy, electron paramagnetic resonance and density functional theory calculations. Moreover, the hierarchical ultrathin and loose two-dimensional nanosheet structure is conducive to expose more active sites and adsorb more reactants. By integrating the efficient adsorption capacity and Z-scheme mechanism, the In2-xS3/Cd1+xIn2-xS4 photocatalyst shows superior photocatalytic CO2 reduction activity and high removal efficiency of dyes and heavy metal. For example, under visible light illumination, it removed almost 100 % of various dyes within 10 min operation, and reduced 100 % Cr(VI) within 1 h, and it also manifested state-of-the-art production rates of 132.5 and 392.1 μmol h−1 g−1 for CH4 and CO, respectively, in reducing CO2 without co-catalyst. A useful inspiration on purposive modulating Z-scheme charge transfer by atomic-level interface engineering was proposed to significantly promote the photocatalytic performance.