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

Abstract

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.