Photocatalytic degradation of organic pollutants and inactivation of pathogens under visible light via CoO _x surface-modified Rh/Sb-doped SrTiO₃ nanocube

Visible light-active rhodium and antimony-co-doped SrTiO₃ nanocubes (Rh/Sb:SrTiO₃ NCs) were synthesized at low temperatures from Rh/Sb:TiO₂ nanorods by the molten salt flux method. The effects of different calcination temperatures (700, 800, and 900 °C) and addition of transition metal oxides (NiO_x, CoO_x, and CuO_x) on the photocatalytic properties of the Rh/Sb:SrTiO₃ NCs were studied. The phase composition and morphology of the Rh/Sb:SrTiO₃ NC photocatalysts (after calcination) were characterized using standard analytical techniques. The synergistic effect of the metal oxides and Rh/Sb:SrTiO₃ NCs boosted the photocatalytic degradation of orange II dye and bisphenol A as well as the inactivation of bacteria. 2 wt% CoO_x-loaded Rh/Sb:SrTiO₃ photocatalyst showed higher photocatalytic performance for the degradation of orange II (96.3%) and bisphenol A (87%) in aqueous solution than Ni (2 wt%) and Cu (2 wt%)-loaded Rh/Sb:SrTiO₃ NC composites. In addition, inactivation of Escherichia coli (96%) and Staphylococcus aureus (97.1%) was achieved over CoO_x (2 wt%)-loaded Rh/Sb:SrTiO₃ for 2 h under visible light irradiation (λ ≥ 420 nm). Further, scavenging experiments confirmed that superoxide anion radicals (^·O₂⁻) and holes (h⁺) are the major active species and OH^· is a minor species responsible for the photocatalytic degradation of the studied organic pollutants. The synthetic strategy presented here offers a novel approach to the design of highly active visible light active photocatalysts for the removal of organic pollutants and inactivation of bacteria in wastewater. Graphical abstract: [Figure not available: see fulltext.]