Hydroxides Ni(OH)2&Ce(OH)3 as a novel hole storage layer for enhanced photocatalytic hydrogen evolution

Abstract

In this work, a novel photocatalyst Ni(OH)₂&Ce(OH)₃@P-CdS was synthesized successfully by phosphorization of CdS and in situ loading of Ni(OH)₂&Ce(OH)₃ on the surface of P-CdS. It was found that the introduction of the element P can expand the absorption range of light, prolong the lifetime of the photoinduced carriers of CdS and enhance photocatalytic hydrogen evolution activity. Importantly, we found that Ni(OH)₂&Ce(OH)₃ can play the role of storing holes, which can efficiently inhibit the recombination of photoinduced electron–hole pairs, thus enhancing hydrogen evolution activity, the hydrogen evolution activity of Ni(OH)₂&Ce(OH)₃@P-CdS is 11.36 mmol g⁻¹ h⁻¹, which is 4.2 times greater than that of P-CdS. A series of characterization methods, including XRD, SEM, TEM, XPS, BET, UV-vis DRS, PL and TRPL spectroscopy and electrochemical methods (IT, LSV, EIS, MS), were performed, aimed at studying the behavior of Ni(OH)₂&Ce(OH)₃@P-CdS. The BET result showed that coupling Ni(OH)₂&Ce(OH)₃ with P-CdS can enhance the specific surface area of the compound catalyst. Also, the UV-vis DRS results showed that the introduction of Ni(OH)₂&Ce(OH)₃ can expand the absorption range of light. Importantly, photoluminescence spectroscopy (PL) showed that the recombination of photoinduced electron–hole pairs was hindered greatly after adding Ni(OH)₂&Ce(OH)₃ into the system.