Enhanced photocatalytic degradation of Bisphenol A under visible light by Cr-TiO2 nanoparticles

In this study, Cr-TiO₂ nanoparticles were synthesized using the sol–gel method, with TiO₂ photocatalyst doped varying Cr concentration. The photocatalysts were assessed for their efficacy in degrading Bisphenol-A under visible light (40 W, 3000 lm, and λ = 400–700 nm, with two maximum peaks at 450 and 545 nm). Optical, morphological, and structural characterization were conducted. TiO₂ doped with 1 % Cr exhibited a remarkable 99 % reduction in BPA degradation within 4 h, compared to the 51.5 % degradation observed with bare TiO₂. This enhancement can be attributed to synergistic effects arising from increased surface area, reduced particle size, and the semi-spherical, uniform morphology of the nanoparticles. Photoluminescence analysis revealed that Cr ion incorporation slowed the recombination processes between photogenerated electron/hole pairs. XPS and Eg data facilitated the calculation of VB and CB values, indicating that the photocatalysts predominantly oxidize the BPA molecule through superoxide ($O_2^{\bullet -}$) and hydroxyl (${\mathrm{HO}}^{\bullet }$) radicals.