Visible-light induced hydrogen generation with ZnO/NiO/Cd1−xZnxS (x = 0.0, 0.2) heterostructures

ZnO/NiO/Cd1−xZnxS (x = 0.0, 0.2) heterostructures have been prepared by a simple solution-based procedure using ZnO/NiO heterostructures prepared by different methods. We obtain good hydrogen evolution activity only with ZnO/NiO heterostructures and not with Zn1−yNiyO solid solutions. The hydrogen evolution activities of ZnO/NiO/CdS and ZnO/NiO/Cd1−xZnxS are 2.2 and 8.2 mmol/h/g respectively with apparent quantum yields of 2.3 and 14% under visible-light irradiation. These values of activity are comparable or superior to those obtained with ZnO/Pt/Cd1−xZnxS and ZnO/Au/Cd1−xZnxS heterostructures. With UV–vis irradiation, the activity found with ZnO/NiO/Cd1−xZnxS is 14–17 mmol/h/g with an apparent quantum yield in the range of 12–15%.