Visible-Light Photocatalytic Activity of N-Doped TiO2Nanotube Arrays on Acephate Degradation

Xinlei Zhang,Yufen Gu,Juan Zhou,Ding Fan

doi:10.1155/2015/527070

Abstract

Highly ordered nitrogen-doped titanium dioxide (N-doped TiO2) nanotube arrays were prepared by anodic oxidation method and then annealed in a N2atmosphere to obtain N-doped TiO2nanotube arrays. The samples were characterized with scanning electron microscope (SEM), X-ray powder diffraction (XRD), X-ray photoelectron spectrum (XPS), and UV-visible spectrophotometry (UV-vis) spectrum. Degradation of the insecticide acephate under the visible light was used as a model to examine the visible-light photocatalytic activity of N-doped TiO2nanotube arrays. The results show that N type doping has no notable effects on the morphology and structure of TiO2nanotube arrays. After N type doping, the N replaces a small amount of O in TiO2, forming an N–Ti–O structure. This shifts the optical absorption edge and enhances absorption of the visible light. N-doped TiO2nanotube arrays subjected to annealing at 500°C in N2atmosphere show the strongest photocatalytic activity and reach a degradation rate of 84% within 2 h.

Highlights

Ordered TiO2 nanotube arrays prepared by electrochemical anodic oxidation have the advantages of traditional TiO2 including high catalytic activity, nontoxicity, and long-term photostability [1], and offer a large surface area, excellent dielectric properties, and strong adsorption capacity
N-doped TiO2 nanotube arrays were prepared by anodic oxidation and annealed in a N2 atmosphere
The degradation of acephate under the visible light shows that the N doping improves photocatalytic efficiency of TiO2 nanotube arrays

Summary

Introduction

Ordered TiO2 nanotube arrays prepared by electrochemical anodic oxidation have the advantages of traditional TiO2 including high catalytic activity, nontoxicity, and long-term photostability [1], and offer a large surface area, excellent dielectric properties, and strong adsorption capacity. Previous studies have found that the appropriate doping or surface modification of TiO2 nanotube arrays, such as nonmetallic element doping [3], metal ion doping [4], surface deposition of precious metals [5, 6], semiconductor modifications [7, 8], and dye-sensitization [9], can effectively broaden the response range of TiO2 nanotube arrays to the visible light and increase their visible-light photocatalytic activity. There are currently many methods for doping N in TiO2 nanotube arrays including heat treatment in NH3 flow [3], chemical vapor deposition [11], and wet impregnation [12, 13] With all of these methods, nonmetal elemental N can be successfully doped into the TiO2 lattice enhancing its response to the visible spectrum. Acephate, which is difficult to be degraded, was used as a model to examine the photocatalytic activity of the prepared N-doped TiO2 nanotube arrays under the visible light

Experimental

Results and Discussion

Conclusion