A rational design of CdS/ZnFe2O4/Cu2O core-shell nanorod array photoanode with stair-like type-II band alignment for highly efficient bias-free visible-light-driven H2 generation

Abstract

In this study, a novel photoanode of ternary CdS/ZnFe2O4/Cu2O core/shell heterojunction nanorod arrays (NRAs) was fabricated via combining two-step hydrothermal method with a facile chemical bath deposition process. Under bias-free visible light irritation, the photocurrent density of the CdS/ZnFe2O4/Cu2O core/shell nanorod array (NRA) photoanode is 3.3 mA cm−2, 2.2 and 3.3-fold as high as that of CdS/ZnFe2O4 and CdS NRAs, respectively. In addition, an average H2 generation rate of the CdS/ZnFe2O4/Cu2O core/shell NRA photoanode is as high as 134 μmol h-1, 2.2-fold of CdS/ZnFe2O4 and 4.5-fold of CdS NRA photoanodes. Furthermore, the CdS/ZnFe2O4/Cu2O core/shell NRA photoanode shows a good photostability and achieves a photocurrent density of over 3 mA cm−2 during continuous light irradiation of 2 h. Significant enhancement for H2 evaluation of the CdS/ZnFe2O4/Cu2O core/shell NRA photoanode is ascribed to the efficient charge transfer and separation, which is achieved by its novel band alignment of stair-like type-II structure.