Solvothermal synthesis of visible-light-active N-modified ZrO2 nanoparticles

This work reports the synthesis and evaluation of visible-light-active N-modified ZrO2 nanoparticles for photocatalytic reduction of aqueous Cr(VI). Using ZrCl4, absolute ethanol and concentrated (65-68 mass%) nitric acid as the starting materials, a simple low temperature (180 degrees C) solvothermal method was proposed for the synthesis of N-modified ZrO2 nanoparticles (which were abbreviated as ZrO2-HNO3). The composition, structure, BET specific surface area and optical property of ZrO2-HNO3 were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, N-2 adsorption and UV-vis diffuse reflectance spectroscopy. The photocatalytic activity of ZrO2-HNO3 was tested in the reduction of aqueous Cr(VI) under visible-light (lambda > 420 nm) irradiation, and compared with that of ZrO2-NH3 (which denoted the product synthesized when 65-68 mass% HNO3 was replaced by 25-28 mass% NH3 center dot H2O). It was observed that ZrO2-HNO3 exhibited remarkable visible-light-absorbing ability and high photocatalytic activity, whereas ZrO2-NH3 exhibited little absorption of visible-light and no photocatalytic activity in the reduction of aqueous Cr(VI) under visible-light (lambda > 420 nm) irradiation. This work suggests that ZrO2-HNO3 is a new promising visible-light-activated photocatalyst. (C) 2014 Elsevier B.V. All rights reserved.