Cu~(2+)/TiO_2对甲基橙的光催化降解机理

以自制的掺铜离子的混晶型二氧化钛为光催化剂,考察了甲基橙光催化降解过程中pH值和光源的影响,提出了两种不同的光催化降解机理:在高压汞灯照射下,TiO2的价带电子被激发到导带,光生电子和空穴主要通过Cu2+ 的短路循环而复合,光催化剂的活性降低;在太阳光照射下,甲基橙发生自身光敏化氧化反应,受激电子从单线态或三线态的甲基橙分子跃迁到TiO2的导带,Cu2+起到电荷传递中继站的作用,加速了注入电子向H2O2的转移,从而促进了甲基橙的光催化降解。

The Photodegradation Mechanism of Dye in The Cu2+/TiO2 Suspension Using Different Lights

Cu()-doped TiO2 photocatalysts with anatase and brookite phases were prepared at high water/titanium ratio under refluxing. The photocatalytic degradation of methyl orange was investigated in the Cu2+/TiO2 suspension using different lights and pH values. In order to decrease the absorption of methyl orange on the Cu2+/TiO2 particles, H2O2 was used instead of O2. The results showed that under UV irradiation, TiO2 first was excited by UV light and subsequently initiated the photodegradation process. But Cu2+ formed a short circuit reaction and enhanced the recombination of photodegradation electrons and holes, and retarded the photodegradation of methyl orange. Under solar irradiation, the dye but not the TiO2 was excited by visible light. Cu2+ played the role of an electron-transfer relay, leading to separation of injected electrons and dye cation radicals. Therefore methyl orange was degradated rapidly.