Promotional Effect of Cu2S-ZnS Nanograins as a Shell Layer on ZnO Nanorod Arrays for Boosting Visible Light Photocatalytic H-2 Evolution

Abstract

The construction of systematically designed hetero-structures with different integrated functionalities in a well-oriented nanoarchitecture is an efficient strategy for attaining high-performance photocatalysts. In this work, a heterostructural platform of ZnO-ZnS-Cu2S core-shell nanorod (NR) arrays is prepared as a photocatalyst for efficient H-2 evolution using visible light. The fabrication is a three-stepprocess involving solution growth of a ZnO NR array, followed by reactive sputtering of Cu2O, and then a sulfidation reaction. Addition of a ZnS interlayer to the ZnO-Cu2S core-shell arrays further extends the visible light absorbance range and promotes effective charge carrier separation. More importantly, the transition of Cu2O into Cu2S ensures the effective interaction of the core-shell assembly with the ZnS-based interface, thereby creating a valuable energy-level configuration and spectral bands that allow accurate separation of the photogenerated charge carrier. The effective H-2 evolution in response to visible light irradiation is 436 mu mol h(-1)g(-1) for the ZnO-ZnS-Cu2S (8 h) NR arrays, which is 2.55 and 1.61 times higher than that achieved with ZnO-Cu2O and ZnO-Cu2S photocatalytic NR arrays, respectively. The pollutant degradation rate for ZnO-ZnS-Cu2S (8 h) NR arrays under visible light irradiation is 7.8, 2.7, and 1.6 times higher than that achieved with pristine ZnO, ZnO-Cu2O, and ZnO-Cu2S core-shell structures, respectively. These visible light-responsive core-shell heterostructures show promising reuse properties and maintain their stability during use.