Reaching Visible Light Photocatalysts with Pt Nanoparticles Supported in TiO₂-CeO₂

Nanostructured catalysts of platinum (Pt) supported on commercial TiO₂, as well as TiO₂-CeO₂ (1, 5 and 10 wt% CeO₂), were synthesized through the Sol-Gel and impregnation method doped to 1 wt% of Platinum, in order to obtain a viable photocatalytic material able to oxidate organic pollutants under the visible light spectrum. The materials were characterized by different spectroscopy and surface techniques such as Specific surface area (BET), X-ray photoelectron spectroscopy (XPS), XRD, and TEM. The results showed an increase in the diameter of the pore as well as the superficial area of the supports as a function of the CeO₂ content. TEM images showed Pt nanoparticles ranking from 2-7 nm, a decrease in the particle size due to the increase of CeO₂. The XPS showed oxidized Pt²⁺ and reduced Pt⁰ species; also, the relative abundance of the elements Ce³⁺/Ce^4- and Ti⁴⁺ on the catalysts. Additionally, a shift in the Eg band gap energy (3.02-2.82 eV) was observed by UV-vis, proving the facticity of applying these materials in a photocatalytic reaction using visible light. Finally, all the synthesized materials were tested on their photocatalytic oxidation activity on a herbicide used worldwide; 2,4-Dichlorophenoxyacetic acid, frequently use in the agriculture in the state of Jalisco. The kinetics activity of each material was measured during 6 h of reaction at UV-Vis 190-400 nm, reaching a removal efficiency of 98% of the initial concentration of the pollutant in 6 h, compared to 32% using unmodified TiO₂ in 6 h.