Unassisted overall water splitting via photoelectrochemical(PEC)light harvesting system as a promising approach has been developed for hydrogen fuel production.However,very few p-type semiconductor photocathodes can simultaneously satisfy all the harsh requirements for overall water splitting in PEC cells: visible light response; appropriate conduction/valence band edges and high stability.In this study,a series of p-type CdSxSe1-x:Cu photocathode which has a tunable bandgap for visible light response,suitable band edge positions for water splitting in basic solution was designed.A variable bandgap from 1.7eV to 2.4eV was achieved by controlling S/Se ratio [1] in CdSxSe1-x:Cu absorber layer via a controllable co-evaporation process.Cu doping concentration has been optimized to enable a cathodic protection from photocorrosion which hindered the stability of traditional Ⅱ-Ⅵ group n-type photoanode in early works [2].A surface modification such as Pt nanoparticles [3] was further applied to enhance both the photocurrent and stability.Ultimately,hydrogen evolution from a stable p-type CdSxSe1-x:Cu photocathode with visible light response in basic solution was achieved.