4-Methyl-5-vinyl thiazole modified Ni-MOF/g-CN/CdS composites for efficient photocatalytic hydrogen evolution without precious metal cocatalysts.

The construction of heterojunction systems is an effective way to efficiently generate hydrogen by water photolysis. In this work, Ni-MOF (trimesic acid, (BTC)) and g-CN (denoted as CN) were combined, and then Ni-MOF/CN was modified by 4-Methyl-5-vinyl thiazole (denoted as MVTh). Finally, CdS was loaded on the surface of Ni-MOF/CN/MVTh to prepare the photocatalyst Ni-MOF/g-CN/MVTh/CdS (denoted as Ni/CN/M/Cd) with a triangular closed-loop path heterojunction for the first time. As a photocatalyst without precious metal cocatalysts, Ni/CN/M/Cd displayed high H evolution (17.844 mmol·g·h) under an optimum CdS loading of 40 wt%. The H evolution rate was approximately 79 times that of Ni-MOF/CN and exceeded those of almost all catalysts based on MOF/CN in the literature. The triangular closed-loop heterojunction formed between Ni-MOF, g-CN, and CdS could realize the directional migration of photocarriers and significantly diminished the transfer resistance of carriers. The Ni in Ni-MOF provided many cocatalytic sites for H evolution via g-CN and CdS. Furthermore, charge carrier separation in Ni-MOF/CN/CdS improved after the innovative addition of MVTh. This study provides a reference for the construction of a closed-loop heterojunction system without precious metal cocatalysts.