Preparation and photocatalytic performance of low-dose La doped WO ₃

Lanthanum-doped tungsten trioxide (La-WO 3 ) was synthesized via a solid-state reaction involving mechanical mixing of lanthanum hydroxide with WO 3 and tungstic acid, followed by calcination. The materials obtained were systematically analyzed through X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), ultraviolet-visible spectroscopy (UV-VIS) diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy (XPS). Characterization revealed a well-defined block-like morphology with homogeneous La distribution. The incorporation of La was found to introduce defect states within the band gap and increase surface hydroxylation, which collectively improved visible-light harvesting and promoted the separation of photogenerated electrons and holes. The influence of La doping concentration on photocatalytic performance was examined, and an optimal formulation was identified. Specifically, the sample prepared with 0.5 g of a hydrothermally derived precursor and 0.05 g of La(OH) 3 (corresponding to 1% La doping) exhibited the highest activity in photocatalytic degradation tests. Based on experimental evidence, a plausible reaction mechanism for the enhanced photocatalysis is discussed.