Zn-Cu-Al层状水滑石基复合氧化物的合成及光催化性能

Synthesis and photocatalytic activity of composite oxide derived from Zn-Cu-Al ternary layered double hydroxides

采用球磨-水热法合成不同投料摩尔比的Zn-Cu-Al层状水滑石(LDHs),LDHs前驱体经焙烧后转变为Zn-Cu-Al复合金属氧化物。用XRD、SEM、TG、DTA和BET等方法对样品前驱体及焙烧产物进行表征。在模拟太阳光照下,以甲基橙(MO)溶液为目标降解物,研究金属离子摩尔比、焙烧温度等对样品的结构、组成形貌及光催化活性的影响。结果表明:当n(Zn):n(Cu):n(Al)投料比为1:2:1时,获得的前驱体具有典型的水滑石片层状结构。最佳前驱体经500℃焙烧后样品中出现Zn O、Cu O和Zn Al2O4 3种氧化物的特征衍射峰,具有较好的结晶度,其比表面积为70.1 m2/g,孔体积为0.26 cm3/g。在模拟太阳光照射下60 min后,0.5 g/L催化剂对25 mg/L甲基橙溶液的脱色率达93.1%。

Zn-Cu-Al layered double hydroxides （LDHs） with different molar ratios of Zn-Cu-Al were prepared via ball mill-hydrothermal method. Zn-Cu-Al composite metal oxide was derived from LDHS precursor by controllable calcination. The Zn-Cu-Al-LDHs samples before and after calcination were eharaeterized by XRD, SEM, TG/DTA and BET measurements. The photocatalytic activity of the as-prepared samples was evaluated by photocatalytic decolorization of methyl orange （MO） aqueous solution under the irradiation of the simulated sunlight. The effects of the molar ratio of metal ion and calcination temperature on the structure, composition, morphology and photocatalytic activity were investigated in detail. The results shows that a layered double hydroxide （LDHs） precursor is obtained under initial molar ratio n（Zn）：n（Cu）：n（Al3＋） of 1：2：1, after calcination at 500 ℃, which leads to a well-crystalline ternary oxide ZnO-CuO-ZnA1204 photocatalyst with BET surface area of 70.1 m2/g and pore volume of 0.26 cm3/g. The maximum photocatalytic decoloration rate of 25 mg/L methyl orange is 93.1% within 60 min under simulated sunlight irradiation at 0.5 g/L concentration of photocatalyst.