Nickel and lanthanum co-doped TiO2 nanoparticles with different metal loading, narrow particle size distribution, and high surface area are synthesized using the sol–gel method. The nanoparticles are further characterized using different techniques like flame atomic absorption spectroscopy (FAAS), specific surface area and porosity measurements, X-ray diffraction (XRD) analysis, fourier transform infrared spectroscopy (FT-IR), UV–vis diffused reflectance spectroscopy (DRS), raman analysis, scanning electron microscopic studies (SEM), photoluminescence (PL) studies, X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopic measurements (EIS). The experimental results of XRD analysis indicated that the co-doping of TiO2 with lanthanum (La) and nickel (Ni) results in an increased in the surface area of TiO2 nanoparticles accomplished by a decrease in the crystallite size from 18.00 to 10.42 nm. The appearance of a new absorption band in DRS spectra at 721 nm caused by the Ni+2 and La+3 doping is responsible for the enhancement of the photocatalytic degradation under visible light. The increased oxygen vacancies, surface defects as well as reduced recombination of charge carriers are confirmed by the PL studies. The photocatalytic experiment for Reactive Yellow-145 (RY-145) is carried out using 1.00 g/L of modified TiO2 suspension at different values of pH and temperature. The experimental results revealed that 96.5% of RY-145 is degraded after a short time of irradiation. The maximum degradation is achieved in case of nanoparticles co-doped with 5% Ni and 3% La ion. Furthermore, the adsorption experiment is also carried out to explore the adsorption of dye by photocatalytic support. The photocatalytic degradation of dye is further confirmed by measuring chemical oxygen demand (COD) values before and after degradation.
