可见光照射下纳晶TiO_2电极对染料污染物的光电催化降解研究

Photoelectrocatalytic degradation of dye pollutants with nano-TiO_2electrode under visible-light irradiation

为揭示TiO2光催化降解染料的反应机理,研究了可见光照射下各种染料污染物在正、负不同偏压下的降解情况.以溶胶-凝胶结合水热法制备的TiO2薄膜为光电极,通过检测反应过程中染料溶液的紫外-可见吸收光谱及总有机碳变化情况,深入探讨了外加电压在光电催化降解染料中的作用.同时,通过电子自旋共振技术检测了染料降解过程中活性自由基的生成情况.实验结果表明,在可见光照射下,外加正偏压时,阳离子染料如罗丹明B和孔雀绿虽也褪色,但矿化率比较低;而负偏压作用时,阳离子型染料在可见光与偏压的共同作用下,以分子中共轭结构的破环为主,产生较高的矿化率.

Photoelectrocatalytic degradations of dye pollutants at different bias under visible irradiation were researched to reveal the mechanism for TiO2 photocatalytic degradation.The prepared TiO2 films by sol-gel and hydrothermal method acted as photoelectrodes.By the examination of UV-visible spectroscopy and removal yield of total organic carbon（TOC）,the effect of bias on the photoelectrocatalytic degradation of dye was investigated,meanwbile,the formation of active oxygen species was examined by electron spin resonance（ESR） spectrometry.These experimental results suggest that the removal yield of TOC is low at positive potential,though the dye as RhB and MG also discolor,yet a rather facile cleavage of the whole conjugated chromophore structure at negative bias leads to the high mineralization yield.