Bimetallic CoMoS₄ Decorated MOF-Derived CdS: A Synergistic Heterostructure for Enhanced Photocatalytic Hydrogen Evolution

Abstract This study developed a novel CdS-based photocatalyst by employing a Cd-MOF precursor and integrating CoMoS 4 as a transition bimetallic cocatalyst by two-step hydrothermal method. CdS was initially obtained by converting Cd-MOF through a sulfidation process, followed by the controlled incorporation of CoMoS 4 at varying molar ratios (2.5%, 5%, and 10%). Structural and morphological analyses (SEM-EDS, XRD, FTIR) confirmed the transformation of Cd-MOF to crystalline CdS and the successful formation of CoMoS 4 /CdS heterojunctions. The incorporation of 2.5 mol% CoMoS 4 significantly increased the BET surface area. UV–vis diffuse reflectance spectroscopy revealed a red-shifted absorption edge and a narrowed band gap of 2.26 eV for the 2.5% CoMoS 4 /CdS composite. Photoluminescence (PL) quenching and XPS analysis indicated improved charge separation and strong interfacial bonding. Mott–Schottky (M-S) measurements revealed conduction band potentials for CdS and CoMoS 4 , supporting the proposed heterojunction mechanism. Among the synthesized composites, the 2.5 mol% CoMoS 4 /CdS catalyst exhibited the highest photocatalytic hydrogen production rate of 5.8 mmol·g⁻¹·h⁻¹ under visible light, representing a tenfold increase compared to bare CdS (0.52 mmol·g⁻¹·h⁻¹). These findings demonstrate that CoMoS 4 is an effective cocatalyst for enhancing hydrogen generation through improved light harvesting and charge-carrier separation, offering a promising strategy for solar-to-hydrogen energy conversion.