Co(1-nSr)TiO3 (n=0, 0.05, 0.1) nano perovskites: Novel photocatalysts synthesized by sol-gel and cold-evaporated sol-gel methods for CO remediation from polluted air

The cobalt-based perovskite photocatalysts doped with three strontium levels, Co(1-nSr)TiO3 (n = 0, 0.05, 0.1), were synthesized using sol-gel (SG) and cold-evaporated sol-gel (CESG) methods and their photocatalytic performance were compared in the field of photocatalytic CO remediation from polluted air. The photocatalytic samples were evaluated by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, solid-state UV spectroscopy, scanning electron microscopy (SEM), Transmission electron microscope (TEM), and BET surface area to evaluate physicochemical properties and their correlation with activity. The results showed that the cold-evaporated synthesis reduced the bandgap and increased the photocatalytic activity. The cold-evaporated synthesis technique enhanced the bandgap range by 15% through 0.05% Sr doping (from 3.3eV at CoTiO3 to 2.85 eV at Co(1-0.05Sr)TiO3, where wavelength activity decreased from 375.97nm (UV region) to 435.33 nm (visible region). The optimum photocatalyst, Co(1-0.05Sr)TiO3 (CESG) exhibited 62.6% CO oxidation under the visible region. The result demonstrated that the CESG synthesis method increases the surface area, decreases the particle size, narrows and uniforms particle size distribution, and changes the crystal structure compared to the SG method. It is concluded that the CESG method is a promising method to synthesize photocatalysts that are activated under visible light for environmental protection.