多层纳米结构蓝色TiO_(2)的电化学氧化性能和稳定性

Hierarchically nanostructured blue TiO_(2) with enhanced electrochemical oxidation performance and stability

蓝色TiO_(2)具有出色的电催化活性,被认为是降解有机污染物的最有潜力的阳极材料之一。然而蓝色TiO_(2)的电催化活性受表面形貌和界面性质的影响较大。本文采用冰水浴阳极氧化和阴极还原制备了由纳米颗粒、多孔层、纳米管阵列依次堆叠的多层纳米结构蓝色TiO_(2),并探究了其电化学氧化性能。与无冰水浴辅助制备的相比,该方法制备的蓝色TiO_(2)具有更多的Ti^(3+)含量、更大的活性面积和良好的电子传输能力,可有效降解亚甲基蓝(97.7%,120min,20mA/cm^(2))和实际废水(COD在180min内被完全去除)。自由基淬灭实验结果表明,添加Na_(2)SO_(4)能促进蓝色TiO_(2)产生羟基自由基和硫酸根自由基,而污染物的降解主要依赖于羟基自由基的氧化作用,硫酸根自由基仅在高Na_(2)SO_(4)浓度、低电流密度和高初始pH条件下有较大贡献。通过冰水浴阳极氧化制备的蓝色TiO_(2)的使用寿命是无冰水浴制备的2.4倍,表明这种多层纳米结构有利于提高蓝色TiO_(2)的稳定性。

Blue TiO_(2)is considered one of the most promising anodes for degradation of organic pollutants due to the excellent electro-catalytic activity.The electro-catalytic activity is subject to morphological structure and interfacial properties of blue TiO_(2).The hierarchically nanostructured blue TiO_(2)was prepared by anodization in ice-water bath and cathodic reduction,and the corresponding electrochemical oxidation performance was studied.The top of blue TiO_(2)was covered with nanoparticles,followed by a porous layer,and nanotube arrays in sequence.The blue TiO_(2)prepared with an ice-water bath possessed more Ti^(3+),electrochemical activity surface and better electron transmission ability compared to that without ice-water bath assisting.The methylene blue was 97.68%removed within 120min under the current intensity of 20mA/cm^(2) and the COD of practical wastewater was completely removed within 180min.The free radical quenching results revealed that adding Na_(2)SO_(4) can promote production of hydroxyl radicals and sulfate radicals on blue TiO_(2),while the electrochemical degradation performance of blue TiO_(2)mainly relied on hydroxyl radicals.Sulfate radicals could contribute a great deal only under the high concentration of Na_(2)SO_(4),low current density and high initial pH.The blue TiO_(2)showed a high service life of 990min,2.4 times as high as that prepared without an ice-water bath,indicating that this special nanostructure was beneficial to improve the stability of blue TiO_(2).