Effect of calcination on structure and photocatalytic property of N-TiO2/g-C3N4@diatomite hybrid photocatalyst for improving reduction of Cr(Ⅵ).

Abstract The N-TiO 2 /g-C 3 N 4 @diatomite (NTCD) composite has been prepared through a simple impregnation method, using titanium tetrachloride as precursor and urea as nitrogen-carbon source. Then the effects of calcination temperature on structure, surface property and photocatalytic activity of the catalysts were investigated. And XRD, TEM, XPS, FTIR and UV–vis diffuse adsorption spectroscopy were used to characterize the obtained powders. The photocatalytic activity of the NTCD was evaluated through the reduction of aqueous Cr (VI) under visible light irradiation (λ > 400 nm). The results demonstrated that the nano-TiO 2 particles ranging from 15 to 30 nm in the crystal of anatase are well deposited on the surface of diatomite in the NTCD-500 which calcined at 500 °C for 2 h. Furthermore, the g-C 3 N 4 with the lay thickness of 0.92 nm was attached to the surface of nano-TiO 2. The N-doped TiO 2 and g-C 3 N 4 doped catalysts could co-enhance response in the visible light region and reduce band gap of NTCD-500 (E g = 3.07 eV). And the NTCD-500 sample exhibited nearly 100% removal rate within 5 h for photocatalytic reduction of Cr (VI) which was higher activity than P25, crude TiO 2 @diatomite and g-C 3 N 4 @diatomite. Graphical abstract Image 1 Highlights • The N-TiO 2 /g-C 3 N 4 @diatomite hybrid photocatalyst was prepared and characterized. • The calcination temperature has significant effect on structure and photocatalytic activity of the catalysts. • The N-TiO 2 /g-C 3 N 4 @diatomite heterostructures exhibit superior Cr(Ⅵ) removal rate under visible light irradiation. • The N-TiO 2 and g-C 3 N 4 work together to enhance the photocatalyst reduction of Cr(Ⅵ). The composite exhibit superior Cr(Ⅵ) removal rate and the calcination temperature has significant effect on structure of the catalysts. [ABSTRACT FROM AUTHOR]