Promotional Effect of Cu₂S–ZnS Nanograins as a Shell Layer on ZnO Nanorod Arrays for Boosting Visible Light Photocatalytic H₂ Evolution
2020
Ranjith, Kugalur Shanmugam | Ranjith Kumar, D. | Huh, Yun Suk | Han, Young-Kyu | Uyar, Tamer | Rajendra Kumar, Ramasamy Thangavelu
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.
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