Roles of Cr3+ doping and oxygen vacancies in SrTiO3 photocatalysts with high visible light activity for NO removal

The photocatalytic degradation of nitrogen monoxide (deNOx) in the gas phase was investigated in a continuous reactor using a strontium titanate-based semiconductor, CaAl2O4:(Eu, Nd)/Cr-doped SrTiO3, and CaAl2O4:(Eu, Nd)/oxygen vacancy-induced SrTiO3 catalysts. Cr doping and oxygen vacancies generation could narrow the band gap of SrTiO3 and affect the photocatalytic performance to varying degrees. The photocatalytic activity of SrTiO3 toward LED light (445 nm)-induced photocatalytic deNOx can be greatly improved by the nonstoichiometric synthesis of SrTiO3, mainly due to oxygen deficiency generation. CaAl2O4:(Eu, Nd)/Cr-doped SrTiO3 composites possessed superiority in NO removal under persistent fluorescence irradiation (440 nm) after the mercury lamp with wavelength larger than 290 nm was turned off.