Erbium and nitrogen co-doped SrTiO₃ with highly visible light photocatalytic activity and stability by solvothermal synthesis

Highlights: • Er/N co-doped SrTiO₃ was prepared by a solvothermal process at low temperature. • The co-doping induces the band gap narrowing and prominent absorbance in visible light region. • The samples show excellent catalytic activity and stability under visible light irradiation. - Abstract: Erbium–nitrogen co-doped SrTiO₃ photocatalysts have been synthesized by a facile solvothermal method. The resulting samples were analyzed by FE-SEM, XRD, BET-surface area and UV–vis. The UV–vis absorption spectra of these powders indicated that erbium–nitrogen co-doped SrTiO₃ possessed stronger absorption bands in the visible light region in comparison with that of pure SrTiO₃. The occurrence of the erbium–nitrogen co-doped cubic SrTiO₃ induced the higher photocatalytic activities for the degradation of methyl orange (MO) under irradiation by ultraviolet light and visible light, respectively, being superior to that of pure SrTiO₃ and commercial TiO₂ (P-25) powders. In addition, the Er–N co-doped SrTiO₃ (initial molar ratios of Sr/Er/N = 1:0.015:0.1, designated as S5) sample showed the best photocatalytic activity with the degradation rate as high as 98% after 30 min under the visible light irradiation. After five cycles, the photocatalytic activity of the S5 catalyst showed no significant decrease, which indicated that the photocatalysts were stable under visible light irradiation