Unlocking the potential of metal Molybdates: A simple chemical method for synthesis and their photocatalytic properties under visible light irradiation

Abstract

This study presents a comprehensive characterization of metal molybdate compounds (ZnMoO₄, NiMoO₄, and CuMoO₄) synthesized via a hydrothermal method followed by a conventional solid-state reaction. Detailed structural and morphological analyses were conducted using X-ray diffraction (XRD) to confirm phase purity and crystal structures, scanning electron microscopy (SEM) and FE-TEM for morphological characterization, and X-ray photoelectron spectroscopy (XPS) for surface chemical composition. Raman spectroscopy provided insights into band mode vibrations in MoO₃ and its metal molybdates, while UV–Vis spectroscopy was employed to estimate the band gaps. The photocatalytic performance of these compounds was assessed through the degradation of methylene blue dye under visible light irradiation, with CuMoO₄ (CM) demonstrating superior activity, followed by NiMoO₄ (NM) and ZnMoO₄ (ZM). Remarkably, CM achieved over 99.5% degradation of RhB dye within 180 min, outperforming the other molybdates. Stability tests over three cycles revealed negligible catalyst loss after 630 min, affirming the exceptional stability of CM compared to ZM and NM. Furthermore, the efficacy of MO and ZM as heterogeneous catalysts for the degradation of mixed organic dye pollutants from textile industry effluents was evaluated, underscoring the significant potential of these metal molybdates, particularly CM, for environmental remediation applications.