Photocatalytic activity enhancement of core-shell structure g-C3N4@TiO2 via controlled ultrathin g-C3N4 layer
Photocatalytic activity enhancement of core-shell structure g-C3N4@TiO2 via controlled ultrathin g-C3N4 layer
复制标题
通过受控超薄g-C3N4层增强核壳结构g-C3N4@TiO2的光催化活性
DOI：
10.1016/j.apcatb.2017.08.004
复制
发表时间：
2018-01-01
影响因子：
22.1
通讯作者：
Zhu, Yongfa
中科院分区：
文献类型：
--
作者：
Wang, Yingying;Yang, Wenjuan;Zhu, Yongfa
采用溶胶 - 凝胶原位包覆再组装的新方法制备了具有可控超薄g - C3N4层（0 nm、1.0 nm、1.5 nm、3.0 nm）的g - C3N4@TiO2核 - 壳结构光催化剂。壳层厚度为1.0 nm的g - C3N4@TiO2样品具有最高的可见光光催化降解苯酚活性，几乎是块状g - C3N4的7.2倍。其最高光电流响应强度比g - C3N4提高了10倍，比TiO2提高了5个数量级。使用g - C3N4@TiO2核 - 壳催化剂时苯酚的去除率为30%，相同催化剂的矿化程度为19.8%，与g - C3N4和TiO2相比显著提高。苯酚降解和矿化性能的提高归因于光致发光（PL）、电化学阻抗谱（EIS）和密度泛函理论计算（DFT）所揭示的有效电荷分离，以及电子自旋共振光谱（ESR）证明超氧自由基是主要的氧化物种。并且核 - 壳结构在催化过程中能有效促进电子从g - C3N4向TiO2转移。重复实验和循环实验结果表明，g - C3N4@TiO2的核与壳之间具有很强的结合力，稳定，无二次污染且便于回收。此外，结果揭示了g - C3N4@TiO2样品上不同g - C3N4壳层（0 nm、1.0 nm、1.5 nm、3.0 nm）与相应催化活性之间的规律，成功建立了构效关系。发现了一种新的催化概念，即层依赖效应，也就是核 - 壳结构中g - C3N4的层数决定光催化活性。（C）2017爱思唯尔有限公司。保留所有权利。
The g-C3N4@TiO2 core-shell structure photocatalysts with controlled ultrathin g-C3N4 layer (0 nm, 1.0 nm, 1.5 nm, 3.0 nm) were prepared by a new method of the sol-gel approaches in situ coating re-assembled. The g-C3N4@TiO2 sample with 1.0 nm thickness of shell layers has the highest visible light photocatalytic degradation phenol activity which is almost 7.2 times as high as that of bulk g-C3N4. The highest photocurrent response intensity is increased by ten times higher than that of g-C3N4 and five orders of magnitude compare to TiO2. The removal rate of phenol using g-C3N4@TiO2 core-shell catalyst is 30% and the degree of mineralization by the same catalyst is 19.8%, which dramatically increase compared with that of g-C3N4 and TiO2. The enhanced performance of the degradation phenol and the mineralization is owing to effective charge separation revealed by the photoluminescence (PL), electrochemical impedance spectroscopy (EIS) and density functional theory calculations (DFT), superoxide radicals as the main oxidative species proved by electron spin resonance spectroscopy (ESR). And the core-shell structure could effectively promote the electron transfer from g-C3N4 to TiO2 during the catalytic process. The results of repetitive experiment and cycle experiment show that the g-C3N4@TiO2 has a strong binding force between the core and shell, which is stable, without secondary pollution and convenient for recovery. What's more, the results revealed the law between the different g-C3N4 shell layers (0 nm, 1.0 nm, 1.5 nm, 3.0 nm) over the g-C3N4@TiO2 samples and the corresponding catalytic activity, which successfully established the structure-activity relationship. A new catalytic concept namely layer-dependent effect was found, that is number of layers over g-C3N4 of the core-shell structure determines photocatalytic activity. (C) 2017 Elsevier B.V. All rights reserved.