Tailoring ZnO properties via La Doping: Improved photocurrent and pollutant degradation efficiency

This study investigates the impact of La³⁺ doping on the structural, optical, magnetic, and photocatalytic properties of ZnO nanoparticles. Pristine and La³⁺ doped ZnO (2 %, 4 %, 6 %) were synthesized via a chemical co-precipitation method and characterized using X-ray diffraction (XRD), UV–visible spectroscopy, Fourier-transform infrared spectroscopy (FTIR), photoluminescence (PL) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and vibrating sample magnetometer (VSM). Rietveld refinement of XRD data confirmed a hexagonal wurtzite structure in all samples, accompanied by strain-induced lattice distortions and atomic displacements due to La³⁺ incorporation. Optical analysis revealed a band gap reduction from 3.12 eV (pristine ZnO) to 2.93 eV for the 2 % La-doped sample, enhancing its visible light absorption. The quenching of PL spectra confirms the increased non-radiative recombination at higher doping levels. Electrochemical studies demonstrated that 2 % doping exhibited the lowest charge transfer resistance, yielding a photocurrent density of 0.36 mA, significantly higher than other concentrations. In photocatalytic testing under natural sunlight, the 2 % La-doped ZnO achieved 90 % degradation efficiency, outperforming other samples. These results underscore the optimized 2 % La-doped ZnO as a promising candidate for environmental remediation and energy harvesting applications.