Hydrogenation Synthesis of Sub-stoichiometric Tungsten Oxide (WOX) Nanoparticles and Its Superior Decompose Rhodamine B Behavior

A metal-free, sub-stoichiometric tungsten oxide (WOX) photocatalyst has been successfully prepared by hydrogenating WO3 plasma nanoparticles at 425 °C. X-ray diffraction (XRD) analysis indicated that the photocatalyst comprised WO3 monoclinic, WO2.9, WO2.7, and WO2.0, depending on the reduction time. Their adsorption and photocatalytic activity on organic contaminants were evaluated by decomposing Rhodamine B (RhB). The prepared WOX demonstrated remarkable capabilities in decomposing 1.2 gL−1 Rhodamine B (RhB) compared to WO3 plasma NPs. WOX-120 exhibited the optimal catalytic performance, with the adsorption capacity for RhB at 174.9 mgg−1, 73 times greater than WO3 plasma NPs. WOX-60 exhibited the highest photodecomposition rate, with a k rate more than 90 times greater than that of WO3 plasma NPs. The investigation into active species in the photocatalytic reaction suggested that superoxide hydroxyl radicals (*OH) and photoinduced holes (h+) were the primary contributors. Furthermore, the photocatalytic degradation of RhB by the synthesized WOX showed improvement when Benzoquinone was introduced into the system as a scavenger, effectively capturing generated electrons and inhibiting their recombination with holes. This research showed the potential for metal-free semiconductor photocatalysts to efficiently remove various organic pollutants through adsorption and photocatalysis under visible light irradiation. Furthermore, the simple reduction process makes this material promising for large-scale catalyst and photocatalyst production.