Solvothermal synthesis of nonmetals-modified SnO2 nanoparticles with high visible-light-activated photocatalytic activity in the reduction of aqueous Cr(VI)

This work took the initiative to conduct the synthesis and evaluation of visible-light-active nonmetals (N, C and CO-modified SnO2 nanoparticles for photocatalytic reduction of aqueous Cr(VI). Using inexpensive SnCl4-5H(2)O, absolute ethanol and concentrated (65-68 mass%) nitric acid as the starting materials, a onestep low temperature (180 degrees C) solvothermal method was developed for the synthesis of nonmetals (N, C and CO-modified SnO2 nanoparticles (which was abbreviated as SnO2-HNO3). The composition, structure, BET specific surface area and optical property of SnO2-HNO3 were characterized by powder X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, N-2 adsorption and UV-vis diffuse reflectance spectroscopy. The photocatalytic activity of SnO2-HNO3 was tested in the reduction of aqueous Cr(VI) under visible-light (lambda > 420 nm) irradiation, and compared with that of SnO2-NH3 (which denoted the product synthesized when 65-68 mass% HNO3 was replaced by 25-28 mass% NH3.H2O). It was observed that SnO2-HNO3 exhibited high photocatalytic activity, whereas SnO2-NH3 exhibited no photocatalytic activity in the reduction of aqueous Cr(VI) under visible-light (2 > 420 nm) irradiation. Besides, the dosage of SnO2-HNO3 and the initial concentration of Cr(VI) aqueous solution had great effects on the photocatalytic reduction rate of Cr(VI). This work suggests that SnO2-HNO3 is a new promising visiblelight-activated photocatalyst in efficient utilization of solar energy for treating Cr(VI) wastewater. (c) 2014 Elsevier B.V. All rights reserved.