Remarkable positive effect of Cd(OH)2 on CdS semiconductor for visible-light photocatalytic H2 production

Abstract

In the past decade, photocatalytic H2 production over CdS semiconductor has garnered considerable interest due to its visible-light response, suitable band structure, and controllable morphologies. To pursue higher photocatalytic efficiency and more feasibility for practical industrial applications, Cd(OH)2 nanoparticle decorated CdS rod composites were designed and successfully fabricated in this study by a facile one-step hydrothermal method in strong alkali NaOH solution. The synthesis process followed a “mother liquor circulation” criteria since no NaOH was lost during the whole preparation course, which could greatly save costs and be conducive to the realization of large-scale production. When the content of Cd(OH)2 was 17.6 mol% in the obtained composite, the photocatalytic H2 production rate reached the highest (579.0 μmol h−1) with the help of 0.6 wt% platinum (Pt), which was more than 386 and 15 times higher than that of Pt/Cd(OH)2 and Pt/CdS, respectively. It was evidenced that such surprising and prominent enhancement of photoactivity was mainly attributed to the presence of Cd0 as an electron transport intermediary, which was produced by in-situ photoreduction of Cd(OH)2 interfacial layer between CdS and Pt. This work could not only highlight the significant roles of Cd(OH)2 on invigorating the photoactivity of CdS for H2 production, but also open an avenue of using the concept of mother liquor circulation in the photocatalyst synthesis process to satisfy the industrial manufacture requirement.