热处理气氛对TiO_2纳米管阵列薄膜光电催化性能的影响

Effect of Heat Treatment on the Photoelectrocatalytic Performance of TiO_2 Nanotube Array Film

采用原位阳极氧化法在Ti基底上制备了高度有序的TiO2纳米管阵列薄膜,分别在O2,空气,Ar和H2气氛中于500oC进行结晶热处理,考察了热处理气氛对TiO2纳米管阵列薄膜光电催化降解亚甲基蓝(MB)反应性能的影响.结果表明,在这些气氛中热处理得到的锐钛矿晶型的纳米管阵列薄膜对MB降解满足一级反应,其速率常数分别为4.967,3.127,1.989和1.625h?1(0.5V).电化学阻抗分析表明,TiO2纳米管的光电催化性能受控于光生电荷的传递特性.在O2中热处理,TiO2纳米管的光吸收及激发性能得以改善,且电荷传递阻抗降低,因而其光电催化性能最好.

Well-aligned and uniform titanium dioxide nanotube array films were fabricated in-situ on titanium substrate by electrochemical anodic oxidation. The resulting amorphous films were crystallized and annealed at 500 oC in different atmospheres such as the oxygen, air, argon, and hydrogen. The photoelectrocatalytic performance of the as-annealed nanotube array films was investigated using methane blue （MB） as a target pollutant. The MB degradation kinetics met the law of first order reaction and the rate constants were 4.967, 3.127, 1.989, and 1.625 h？1 at 0.5 V bias, respectively. Electrochemical impedance spectroscopy analysis revealed that the MB degradation was governed by the charge transfer characteristic of the nanotube. The improvement of light absorbance and excitation and the lower transfer impedance might be critical factors for the efficient photoelectrocatalysis of TiO2 array films annealed in oxygen.