N-Doped K3Ti5NbO14@TiO2 Core-Shell Structure for Enhanced Visible-Light-Driven Photocatalytic Activity in Environmental Remediation

Xin Gao,Chen Wang,Xinguo Xi,Qixiang Xu,Ting Chen,Hongjie Lv,Chao Liu

doi:10.3390/catal9010106

Abstract

A novel N-doped K3Ti5NbO14@TiO2 (NTNT) core-shell heterojunction photocatalyst was synthesized by firstly mixing titanium isopropoxide and K3Ti5NbO14 nanobelt, and then calcinating at 500 °C in air using urea as the nitrogen source. The samples were analyzed by X-ray diffraction pattern (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-Vis absorption spectroscopy and X-ray photoelectron spectroscopic (XPS) spectra. Anatase TiO2 nanoparticles were closely deposited on the surface of K3Ti5NbO14 nanobelt to form a nanoscale heterojunction structure favorable for the separation of photogenerated charge carriers. Meanwhile, the nitrogen atoms were mainly doped in the crystal lattices of TiO2, resulting in the increased light harvesting ability to visible light region. The photocatalytic performance was evaluated by the degradation of methylene blue (MB) under visible light irradiation. The enhanced photocatalytic activity of NTNT was ascribed to the combined effects of morphology engineering, N doping and the formation of heterojunction. A possible photocatalytic mechanism was proposed based on the experimental results.

Highlights

Nowadays, two main problems of environmental pollution and energy shortage are major challenges with the industrial development, and many organic pollutants will be generated, especially leading to the serious water pollution problem [1,2]
After coupling with TiO2, both K3 Ti5 NbO14 and anatase TiO2 phases (JCPDF: No 21-1272) exist in the resulted K3 Ti5 NbO14 @TiO2 (TNT) composite, indicating that the crystal structure of K3 Ti5 NbO14 can be well maintained after the deposition of TiO2 on its surface
The characteristic peaks of K3 Ti5 NbO14 in TNT composite are broaden in comparison with pure K3 Ti5 NbO14, suggesting the decreased crystallization of TNT derived from the formation of TiO2 nanoparticles on the surface of K3 Ti5 NbO14 nanobelts

Summary

Introduction

Two main problems of environmental pollution and energy shortage are major challenges with the industrial development, and many organic pollutants will be generated, especially leading to the serious water pollution problem [1,2]. Considering the comprehensive economic benefits, catalytic efficiency, and absence of secondary pollution for this technique, many semiconductor photocatalysts have been widely applied for the removal of produced waste water [6,7,8]. TiO2 has been widely investigated and commonly used in photocatalytic applications because of its excellent biological and chemical ability, low cost, and nontoxicity [9,10,11,12]. The pure TiO2 exhibits the drawbacks of having a wide band gap value and high recombination rate of photogenerated charge carriers, which will cause low quantum efficiency and limit its application [13,14,15]. It is necessary to carefully construct photocatalysts with a high efficiency so as to improve photocatalytic activity

Results

Discussion

Conclusion