Development of SrTiO3 Photocatalysts with Visible Light Response Using Amino Acids as Dopant Sources for the Degradation of Organic Pollutants in Aqueous Systems

Abstract

N-doped and N,S-co-doped SrTiO3 photocatalysts were prepared using glycine and L-histidine amino acids as nitrogen sources and L-cysteine as nitrogen and sulphur source. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 porosimetry, UV-Vis diffuse reflectance (DRS) and fluorescence spectroscopy, dynamic light scattering (DLS). Cubic SrTiO3 phase is formed in all samples, with crystal size ranged from 14.2 nm to 35.7 nm. The catalysts’ specific surface area and porosity depend on the amino acid dopant showing micro-mesoporosity for glycine, mesoporosity for histidine and non-porosity for cysteine. The lowest band gap (2.95 eV) was observed for the sample G-N-STO3 prepared with glycine (N:Sr:Ti 3:1:1 molar ratio) which produced also the higher amount of •OH radicals. The photocatalytic activity was tested against the degradation of methylene blue (MB) dye under UV-Vis and visible light irradiation following first-order kinetics.