The Outstanding Promotion Effect of La on Ru/Co ₃ O ₄ Nanofiber Catalyst for Catalytic Wet Air Oxidation of Phenol

Developing highly efficient catalysts for the catalytic wet air oxidation (CWAO) of phenolic wastewater remains a challenge. In this paper, a series of Ru catalysts supported on La-doped nanofibers (Ru/LaCoO4-x%) were prepared via an electrospinning and impregnation method. The effect of La content (5%, 10% and 15%) on the physicochemical properties and catalytic performance in phenol degradation was systematically investigated. Characterization results (XRD, XPS, H2-TPR, O2-TPD) indicate that an optimal La doping of 10% induces significant lattice distortion, maximizes the concentration of oxygen vacancies and surface Co3+ sites, and enhances the mobility of chemisorbed oxygen. Furthermore, La doping strengthens the metal–support interaction, leading to superior dispersion of Ru species and facilitating electron transfer. These synergistic effects endow the Ru/LaCoO4-10% catalyst with the highest redox activity, which achieved a superior TOC conversion rate of 88% at 160 °C, significantly outperforming the undoped and other La-doped catalysts. The outstanding performance is attributed to the optimized balance between structural disorder, defect density, and electronic modification, underscoring the efficacy of moderate La doping in designing high-performance CWAO catalysts.