Enhancement Mechanism of Photocatalytic Hydrogen Production Activity of CeO<sub>2</sub>/CdS by Morphology Regulation
Ziwei Liu, Yanli Zhuang, Limin Dong, Hong-Xu Mu, Dan Li, Fengming Zhang, Huanyan Xu, Haijiao Xie
Abstract
The morphology of the catalyst is one of the important factors affecting the photocatalytic activity. Being highly specific exposed to different crystal facets has a significant effect on photocatalysis. Thereby, well-interpreted examples of CeO 2, dominated by (311) and (220), respectively, are presented to explore the reactivity of photocatalyzed special exposed crystal surfaces in photocatalyzed hydrogen evolution. The photocatalytic activity of NR-CeO 2 (311) was testified to be remarkably higher than NF-CeO 2 (220). Further electrochemical detection studies have confirmed that the difference in activity is not only due to the different morphologies of the materials but also controlled by the different exposing facets, resulting in photogenerated carriers and effective spatial separation. When the mass proportion of NR-CeO 2 and CdS is 1:4, the photocatalytic activity of NR-CeO 2 /CdS is highest (about 444 μmol·g –1 ·h –1 ), which is about 19.7 times stronger than that of pure CdS. The reaction mechanism was further confirmed by the DFT calculation. Effective separation of photogenerated carriers and specific rod-like shapes and surface atomic arrangements contribute to the high activity of well-designed CeO 2 /CdS photocatalysis. Combined with the experiment and characterization, the regulation mechanism of the CeO 2 morphology and crystal surfaces with different morphologies was proposed, and the photogenerated carrier transport was evaluated. The results show that the morphology and crystal facets have great influence on the photocatalytic activity of CeO 2 .