Hydrogen-Treated TiO₂ Nanorods Decorated with Bimetallic Pd-Co Nanoparticles for Photocatalytic Degradation of Organic Pollutants and Bacterial Inactivation

Herein, first, we synthesize a multifunctional photocatalyst via metal oxides loaded (Co/Pd) on acid-treated TiO₂ nanorods (ATO) and further introduce hydrogen annealing treatment. The hydrogen annealing treatment introduces metal oxides converted into a bimetallic form and delays the photogenerated charge recombination process. Also, oxygen vacancies are formed due to the partial reduction of Ti⁴⁺ to Ti³⁺ sites. In addition, oxygen vacancies help to improve photocatalytic degradation and antibacterial activity. The hydrogen-treated photocatalyst (Pd(1)Co(1)/ATO (red)) demonstrates high degradation efficiencies of 99.63 and 99.90% (180 min) for orange II dye and BPA degradation, respectively, and an antibacterial activity of 97.00% (120 min) under one sun irradiation. In the photocatalytic removal of abiotic pollutants and live bacteria, the trapping experiment suggests that radical species (^•O₂^- and ^•OH), assisted by photoinduced holes, are responsible for the high activities. The photoelectrochemical performance and time-resolved PL (TRPL) study illustrate that Pd(1)Co(1)/ATO (red) reveals superior photoelectrochemical charge separation (electron-hole), lower resistance, and shorter lifetime (τ₁ = 0.40 ns) as a photocatalyst. Finally, plausible charge transport mechanisms are proposed for the photocatalytic degradation of organic dye and bacterial disinfection over the Pd(1)Co(1)/ATO (red) photocatalyst.