Light-Assisted Preparation of a ZnO/CdS Nanocomposite for Enhanced Photocatalytic H₂ Evolution: An Insight into Importance of in Situ Generated ZnS

Abstract

In our work, ZnO/CdS hybrid photocatalysts were prepared by a simple and reproducible photodeposition method and the content of deposited CdS can be varied by irradiation time. The ZnO/CdS photocatalysts showed good photocatalytic H 2 evolution activities in aqueous Na 2 S + Na 2 SO 3 solution. When the content of CdS loading increased to 22.91% after an irradiation time of 120 min (ZnO/CdS-T120), the highest photocatalytic activity was obtained (1725 μmol g –1 h –1 ), which was about 9.2 and 34.5 times than that of single ZnO and CdS photocatalysts. At the same time, ZnO/CdS-T120 presented stable photocatalytic ability (no noticeable degradation of H 2 evolution in four repeated runs in 48 h). Compared with other reported H 2 evolution photocatalysts, ZnO/CdS-T120 showed higher H 2 evolution activity and stability. Additionally, ZnO/CdS-T120 has a good natural sunlight driven H 2 evolution ability (2077 μmol g –1 h –1 ). ZnS was proved to generate on ZnO/CdS-T120 surface in process of photocatalytic H 2 evolution based on structural analyses of recycle ZnO/CdS-T120. The formation of ZnS enhanced the photocatalytic H 2 evolution activity of ZnO/CdS and extended the visible light adsorption region. Meanwhile, the generation of ZnS increased the transfer interfaces for photogenerated charge carriers and consequently promoted the separation of photogenerated electrons and holes.