Synthesis of Cu–Mo/TiO ₂ and Co–Mo/TiO ₂ photocatalysts for the efficient degradation of organic pollutants in water

Co-doped titanium dioxide materials were successfully synthesized by the sol–gel method. Molybdenum was incorporated into all materials at 0.5 wt %, while the co-dopants, copper and cobalt, were added at 0.2–0.5 wt %. The co-doped TiO ₂ photocatalysts were characterized by XRD, SEM, N ₂ physisorption, UV–vis diffuse reflectance spectroscopy, and photoluminescence spectroscopy. The structural characterization showed stabilization of the anatase phase, and lattice distortion was evidenced after dopant incorporation into the TiO ₂ structure. Morphological characterization showed poorly defined spherical particles that decreased in size with increasing Cu and Co concentrations. PL spectra showed an additional signal attributed to the ability of the metal dopants to capture electrons. The point of zero charge of the photocatalytic systems TiO ₂ , Cu–Mo/TiO ₂ , and Co–Mo/TiO ₂ was evaluated and reported. Materials with lower concentrations of the co-dopants Cu and Co were more efficient at degrading ketoprofen. The most efficient photocatalyst was 0.2 Cu–0.5 Mo/TiO ₂ , which achieved the complete degradation of ketoprofen and 90% of mineralization. It was determined that HO ^· radicals play an important role in the oxidation reactions.