低含量Ni掺杂TiO2光催化剂及其在水溶液体系中的重复使用性能

利用溶胶-凝胶法制备了低含量Ni掺杂的TiO₂光催化剂粉体，考察了催化剂在甲基橙水溶液中的重复使用性能，并用XRD、XPS和N₂吸附-脱附等手段对催化剂进行了表征分析。结果表明，当掺杂Ni物质的量分数为0.3%和焙烧温度400 ℃时，制备的Ni/TiO₂的光催化降解甲基橙水溶液的活性高于纯TiO₂的光催化降解活性。Ni/TiO₂光催化剂在水溶液体系重复使用过程中，催化活性急剧下降，重复使用性能较差。Ni掺杂使TiO₂上产生具有较低结合能的低价钛离子如Ti^3＋，使表面缺陷（或氧空位）增加。比表面积和氧空位增加可能是Ni掺杂提高TiO₂光催化活性的主要原因。Ni流失可能是Ni/TiO₂在水溶液体系中重复使用性能较差的原因。

Low content nickel-doped TiO2 and its photodegradation activities in recycling process for aqueous system

Low content nickel-doped TiO2 catalysts were prepared by sol-gel method and were character-ized by X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS) and N2 adsorption-desorption. The photodegradation activity of nickel-doped TiO2( Ni/TiO2) in recycling process was investigated by degradation of methyl orange in aqueous solution. The results indicated that the photodegradation activity of Ni/TiO2 with nickel-doped molar fraction of 0.3% calcined at 400℃ was much higher than that of pure TiO2. The photodegradation activity of Ni/TiO2 was decreased sharply in recycling process. XPS characterization showed that there were low valence titanium ions with lower binding energy (such as Ti3+ ) on the surface of Ni/TiO2. The higher surface area and more amount of oxygen vacancy ( induced by low valence titanium ions)on Ni/TiO2 were the main factors for better photedegradation activity of Ni/TiO2 compared with TiO2. The loss of nickel on Ni/TiO2 was speculated as one of the reasons that the photodegradation activity of the catalyst became much lower in recycling process for aqueous system.