Layered Molybdenum (Meta)phosphate for Photoreduction of Hexavalent Chromium and Degradation of Methylene Blue under Sunlight Radiance.

Noble metal, semiconductor, or metal-free nanomaterials have shown promising applicability as potential photocatalyst materials. A one-step process has been established for the synthesis of layered molybdenum (meta)phosphate [MoO(PO)] using a solvothermal method. The nanopowders were characterized by X-ray diffraction (XRD), UV-visible spectroscopy (UV-vis), scanning electron microscopy (SEM), infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), photoluminescence spectroscopy (PL), surface area analysis (Brunauer-Emmett-Teller (BET)), electron spin resonance (ESR), and high-resolution transmission electron microscopy (HRTEM). Through this study, we demonstrate the use of MoO(PO) as a photocatalyst for wastewater treatment. The photoreduction of toxic Cr to Cr by layered molybdenum (meta)phosphate is investigated using formic acid as a scavenger. This catalyst has also been used for photodegrading organic dyes like methylene blue. MoO(PO) has been shown to complete photoreduction of toxic Cr to Cr in 6 min and achieved 78% degradation efficiency for methylene blue in 36 min. The reactive species trapping experiments revealed that the key active species like O , OH, and h can exist and play an important role in methylene blue photodegradation.