磷酸根和Nafion修饰TiO 2 表面腐植酸调控的可见光催化降解苯酚性能
磷酸根和Nafion修饰TiO 2 表面腐植酸调控的可见光催化降解苯酚性能
复制标题
DOI：
10.1016/s1872-2067(17)62951-6
复制
发表时间：
2017-12
影响因子：
16.5
通讯作者：
Longhui Zheng;Xiao Yu;Mingce Long;Qilin Li
中科院分区：
文献类型：
--
作者：
Longhui Zheng;Xiao Yu;Mingce Long;Qilin Li
腐殖酸（HA）对TiO2光催化降解苯酚有抑制作用，但对TiO2有敏化作用，并能诱导明显的可见光活性。HA的这种有利作用在磷酸盐改性的TiO 2（P-TiO 2）上可以忽略不计，但在Nafion改性的TiO 2（Nf-TiO 2）上显著更强。当HA浓度为20 mg/L时，Nf-TiO 2催化剂降解苯酚的反应速率常数从（0.003 ± 0.001）min-1增加到（0.025 ± 0.003）min-1. HA对P-TiO 2和Nf-TiO 2吸附性能的不同影响不能归因于吸附性能的变化，因为在HA初始浓度为20 mg/mL时，P-TiO 2和Nf-TiO 2的吸附容量仅略低于TiO 2。采用清除剂测试、电子顺磁共振光谱和H2O2检测来了解P-TiO 2/HA悬浮液的低VL活性。TiO2和Nf-TiO2悬浮液中苯酚降解的主要活性物种为超氧自由基。在P-TiO 2/HA悬浮液中有可忽略不计的超氧自由基，可能是因为发生了直接的四电子氧还原反应。基于Mott-Schottky曲线和电化学阻抗曲线，对Nf-TiO 2的VL活性进行了分析。Nafion改性导致能带位置的阴极位移，增加电子密度，并减少电阻的电子转移通过TiO 2和电解质之间的界面。所有这些因素都促进了电子转移，提高了活性物种的产生。因此，磷酸盐改性没有提高HA敏化的TiO2的VL响应，低浓度的HA可以促进Nafion表面改性的TiO2上的有机污染物的VL光催化降解。
Although humic acid (HA) can inhibit TiO2photocatalysis, it can sensitize TiO2and induce significant visible-light (VL) activity in phenol degradation. This favorable effect of HA was negligible on phosphate-modified TiO2(P-TiO2), but significantly stronger on Nafion-modified TiO2(Nf-TiO2). The reaction rate constants for phenol degradation on Nf-TiO2increased from (0.003±0.001) to (0.025±0.003) min−1when the reaction was performed in the presence of 20 mg/L HA. The different effects of HA on P-TiO2and Nf-TiO2photocatalysis cannot be attributed to adsorption changes, because the adsorption capacities of P-TiO2and Nf-TiO2were only slightly lower than that of TiO2at an initial HA concentration of 20 mg/mL. Scavenger tests, electron paramagnetic resonance spectroscopy, and H2O2detection were taken to understand the low VL activity of the P-TiO2/HA suspension. The main active species for phenol degradation in the TiO2and Nf-TiO2suspensions were superoxide radicals. There were negligible amounts of superoxide radicals in the P-TiO2/HA suspension, possibly because a direct four-electron oxygen reduction reaction occurred. The better VL activity of Nf-TiO2was rationalized on the basis of Mott–Schottky and electrochemical impedance plots. Nafion modification resulted in cathodic shifts of the energy band positions, increased electron density, and less resistance to electron transfer across the interface between TiO2and electrolytes. All these factors facilitated electron transfer and improved the production of active species. Phosphate modification therefore did not improve the VL response of HA sensitized TiO2, and low concentrations of HA can facilitate VL photocatalytic degradation of organic pollutants on Nafion surface-modified TiO2.