Core-Shell Heterostructured and Visible-Light-Driven Titanoniobate/TiO2 Composite for Boosting Photodegradation Performance.

Chao Liu,Zitong Han,Zhigang Zou,Xin Gao,Yue Feng,Qinfang Zhang,Guiyun Yu,Yao Sun,Xinguo Xi

doi:10.3390/nano9101503

Chao Liu, Zitong Han + Show 7 more

Open Access

https://doi.org/10.3390/nano9101503

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Abstract

Herein, we report a one-dimensional (1D) S-doped K3Ti5NbO14@TiO2 (STNT) core-shell heterostructured composite with an enhanced photocatalytic degradation activity under visible light, which was prepared by a simple reassembly-calcination method using thiourea as the S source. The anisotropically shaped rods are favorable for the rapid transport of photogenerated charge carriers. The substitution of Ti4+ by S6+ is primarily incorporated into the lattice of the TiO2 shell so as to create an intra-band-gap state below the conduction band (CB) position, giving rise to Ti−O−S bonds and thus the visible light response. The presence of electron-deficient S atoms is of benefit to the decreased recombination rate of photogenerated electrons and holes by capturing electrons (e−). Meanwhile, a tight close interface between K3Ti5NbO14 and TiO2 was formed to achieve a nano-heterojunction structure, leading to the fostered separation of its interfacial photogenerated electrons and holes. The visible-light-driven photocatalytic degradation of methylene blue (MB) by STNT composites is higher than that by pure K3Ti5NbO14, owing to the synergistic effects of S doping and heterojunction. A possible photocatalytic mechanism was proposed with a reasonable discussion. This work may provide an insight into constructing highly efficient core-shell photocatalysts used toward sustainable environmental remediation and resource shortages.

Highlights

With the rapid development of global industrialization and population explosion, organic pollutants show negative impacts on human health and ecosystem equilibrium due to the difficult removal from wastewater [1,2,3]
Pure TiO2 shows some drawbacks, such as it is unresponsive to visible light and it has a quick recombination rate of photogenerated electron–hole pairs [8,9,10]
Anisotropically shaped rods can provide a channel for the rapid transport of charge carriers along the longitudinal direction, leading to the decreased recombination rate of photogenerated electrons and holes [14]

Summary

Introduction

With the rapid development of global industrialization and population explosion, organic pollutants show negative impacts on human health and ecosystem equilibrium due to the difficult removal from wastewater [1,2,3]. The improved photocatalytic activity was ascribed to the synergistic effects of anisotropic K3Ti5NbO14 rod for the high-charge carrier mobility, the layered heterojunction for quick separation of photo-induced electrons and holes, and N-doping for the improvement of the light response region. Park et al combined Ti5NbO14 nanosheets with Ag2CO3/Ag to construct Ag2CO3/Ag-Ti5NbO14 multicomponent nanohybrids, which exhibited a much more superior photodegradation activity under visible light in comparison to the unhybridized Ag2CO3 sample [23] It highlighted that the construction of the heterojunction structure was beneficial to the retarded recombination rate of photogenerated electrons and holes, leading to the remarkable improvement of photodegradation activity. We successfully fabricated 1D S-doped K3Ti5NbO14@TiO2 (STNT) core-shell heterostructured composites, showing an improved visible-light-driven photodegradation activity for the removal of methylene blue (MB) due to the combined effects of S doping and heterojunction. This work will provide an insight into fabricating core-shell hetero-structured catalysts with a high photocatalytic performance

Materials and Methods

Powder X-Ray Diffraction Analysis

UV-Vis Analysis

Electrochemical Analysis and PL Analysis

Photocatalytic Mechanism