Latex copolymer-assisted synthesis of metal-doped TiO2 mesoporous structures for photocatalytic applications under solar simulator

A novel and facile route was developed using latex copolymer to synthesize pure and metal-doped mesoporous M/TiO₂ (MNPs). The influence of 2.5 mol% metal doping (M = Pd, Ag, Ni and Cu) on the physical features and photocatalytic responses of M/TiO₂ was analyzed by complementary characterization methods. XRD and Raman investigations reveal that anatase and brookite structures for the prepared mesoporous nanoparticles (NPs) are being stabilized by suitable annealing at 500 °C for 2 h. A band gap varying between 2.49 and 3.08 eV was calculated using Kubelka Munk model and Tauc plot. The prepared mesoporous materials were found to have approximate sizes between 5 and 20 nm with a specific surface area up to 97.97 m² g⁻¹. Photocatalytic studies were carried out in model solutions of water and methylene blue (MB) dyes under visible irradiation in the presence of pure and metal-doped mesoporous M/TiO₂ (MNPs). The samples show a sequential combination of adsorption and photocatalytic dye degradation process with variable reaction rate constants depending on the doping metallic elements. This manifested itself by a high ability to adsorb methylene blue dye (86% of the initial solution with 2 × 10⁻⁵ M, 5 mg of TiO₂) and complete photocatalytic degradation after 2 h (98%). In the same reaction conditions, Ag/TiO₂ and Ni/TiO₂ allowed to mineralize 91% and 88% of the initial concentration MB, respectively, whereas the Cu/TiO₂ can only mineralize 58% of MB.