Promotional Effect of Cu<sub>2</sub>S–ZnS Nanograins as a Shell Layer on ZnO Nanorod Arrays for Boosting Visible Light Photocatalytic H<sub>2</sub> Evolution
Kugalur Shanmugam Ranjith, Deivasigamani Ranjith Kumar, Yun Suk Huh, Young‐Kyu Han, Tamer Uyar, Ramasamy Thangavelu Rajendra Kumar
Abstract
The construction of systematically designed heterostructures 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 H2 evolution using visible light. The fabrication is a three-step process 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 H2 evolution in response to visible light irradiation is 436 μmol 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.