4-Methyl-5-vinyl thiazole modified Ni-MOF/g-C₃N₄/CdS composites for efficient photocatalytic hydrogen evolution...

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-C₃N₄ (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-C₃N₄/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 H₂ evolution (17.844 mmol·g^-1·h^-1) under an optimum CdS loading of 40 wt%. The H₂ 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-C₃N₄, and CdS could realize the directional migration of photocarriers and significantly diminished the transfer resistance of carriers. The Ni²⁺ in Ni-MOF provided many cocatalytic sites for H₂ evolution via g-C₃N₄ 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.