A facile preparation of dual-phase nitrogen-doped TiO2-SrTiO3 macroporous monolithic photocatalyst for organic dye photodegradation under visible light

A dual-phase nitrogen-doped TiO2-SrTiO3 macroporous monolithic photocatalyst was fabricated through the impregnation of the preformed TiO2 gel in a Sr2+-containing alcohol-water solution followed by nitridation under a modest flow of ammonia gas at 800 °C for 2 h. The fabricated monolithic photocatalyst was characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), mercury porosimetry, N2 gas adsorption (SBET), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible (UV-vis) spectroscopy. The XRD results showed that the fabricated monolithic photocatalyst is comprised of two crystalline phases (anatase TiO2 and SrTiO3) and possesses a highly interconnected (co-continuous) macroporous framework. The photocatalytic activity of the fabricated monolithic photocatalyst was evaluated by the photodegradation of organic dye (Rhodamine B) over the samples under visible light. As expected, the N-doped TiO2-SrTiO3 macroporous monolithic photocatalyst showed a higher photodegradation rate constant (0.0019 min−1) compared to the undoped TiO2-SrTiO3 (0.0010 min−1) under the identical experimental conditions due mainly to the band gap reduction.