Designing Z-scheme CdS/WS2 heterojunctions with enhanced photocatalytic degradation of organic dyes and photoreduction of Cr (VI): Experiments, DFT calculations and mechanism

•A Z-scheme CdS/WS2 heterojunction with built-in electric field was successfully constructed.•Z-scheme configuration is confirmed through experiments and DFT calculations.•Photogenerated carrier separation and transfer was accelerated at the interface.•Excellent ability for photocatalytic degradation and mineralization of dyes and reduction of Cr(VI) is exhibited.•CdS/WS2 heterojunction has excellent stability and photocorrosion resistance.