Breaking new grounds: Solid-state synthesis of TiO2–La2O3–CuO nanocomposites for degrading brilliant green dye under visible light.

Environmental pollution, particularly from industrial dyes and chemicals, poses a significant threat to ecosystems and human health. Traditional pollution mitigation methods are often inefficient and costly. Photocatalysis has emerged as a promising solution for degrading pollutants using light energy. Titanium dioxide (TiO 2) is a widely studied photocatalyst due to its stability, non-toxicity, and strong oxidative power. However, its efficiency is limited by a wide bandgap, restricting absorption to the UV region, and rapid electron-hole recombination. To address these limitations, doping TiO 2 with materials (La 2 O 3 and CuO) can enhance its photocatalytic activity under visible light. This study investigates the enhancement of TiO 2 nanocomposites by incorporating La 2 O 3 and CuO. X-ray diffraction (XRD) revealed that the nanocomposites retained the TiO 2 anatase and rutile phases with their improved crystallinity. Scanning electron microscopy (SEM) displayed spherical nanoparticles forming agglomerates, typically due to high surface energy. Energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) confirmed the presence of La and Cu in the TiO 2 matrix. Fourier-transform infrared (FTIR) spectroscopy identified characteristic vibrational modes of Ti–O, La–O, and Cu–O bonds, suggesting strong interactions between dopants and TiO 2 lattice. Ultraviolet–visible (UV–vis) spectroscopy showed a red shift in absorption spectra with La 2 O 3 and CuO addition, reducing the bandgap energy from 3.23 eV (pure TiO 2) to 2.27 eV for the TiO 2 –0.1La 2 O 3 –0.2CuO composite. Photoluminescence (PL) spectroscopy indicated improved charge separation and reduced electron-hole recombination rates in the synthesized nanocomposites. Photocatalytic performance was evaluated by degrading brilliant green (BG) dye under visible light. The TiO 2 –0.1La 2 O 3 –0.2CuO (TLC 0.2) nanocomposite achieved the highest dye degradation of over 95% after 204 min under optimal conditions (C o = 17 mg/L and 1 g/L). Adding the inorganic agent Na 2 SO 4 to this process significantly enhanced the photocatalytic activity, increasing degradation from 56% to 95% after 180 min of visible light irradiation. TLC 0.2 exhibited a high stability of dye degradation efficiency after six consecutive photocatalysis cycles. La 2 O 3 and CuO doping significantly enhance TiO 2 nanocomposites' crystalline structure, morphology, optical property, and photocatalytic efficiency. TLC 0.2 has a potential use for environmental remediation and solar energy conversion. [ABSTRACT FROM AUTHOR]