Exploring the potential of defective black TiO2 and palladium-doped black TiO2 catalysts in battery applications and the photocatalytic degradation of organic dyes

Abstract In this study, we investigate the potential of defect engineering and metal doping in a TiO 2 matrix for battery applications and the photocatalytic degradation of methylene blue (MB) and methyl orange (MO) dyes. The TiO 2 defect engineering was achieved through the NaBH 4 thermal reduction method, while the doping was achieved through a palladium deposition-reduction approach. Techniques such as XRD, FTIR, Raman, BET, HRTEM, UV–Vis DRS, PL, CV, EIS, LSV, and DFT calculations were employed to elucidate the properties of developed catalysts. Among prepared catalysts, the 3.0wt% Pd-doped black TiO 2 (3.0-PdbTO) exhibits an initial discharge capacity of 3234 mAh g -1 at a current density of 200 mA g −1, which is 19.4 and 92.4 times higher than that of black TiO 2 and pristine TiO 2 , respectively. Higher discharge capacity was attributed to the enhanced electrochemical and electronic properties introduced by defect states within the TiO 2 framework. Furthermore, the 3.0-PdbTO catalyst demonstrates excellent discharge stability, with more than 90% capacity retention over 20 cycles. During photocatalytic degradation, 3.0-PdbTO exhibits excellent photocatalytic performance with 85% degradation efficiency of MB and 70% degradation efficiency of MO, within 80 min of light irradiation, ascribed to an enhancement in light absorption and improved separation of charge carriers brought in by defect states and surface plasmon resonance effect of palladium metal. This work presents a strategy for integrating defect engineering with metal doping to design multipurpose catalysts for next-generation battery technology and advanced wastewater treatment.