固相反应合成NiO-ZnO纳米复合光催化剂

Preparation of NiO-ZnO nanocomposite photocatalyst by solid state reaction

以ZnSO4·7H2O、NiSO4·6H2O和(NH4)2C2O4·H2O为原料,通过球磨固相反应首先合成出前驱物NiC2O4.2H2O-ZnC2O4·2H2O。进而将该前驱物加热分解制得p-n结型NiO-ZnO纳米复合光催化剂。用X射线衍射分析对产物的物相组成、平均晶粒大小进行表征。结果表明,在400～800℃热处理温度内,产物NiO-ZnO由立方相NiO和六角相ZnO组成;500℃煅烧2 h的NiO-ZnO样品中NiO和ZnO的平均粒径分别约为31.7 nm和17.6 nm。以Cr6+溶液和甲基橙溶液的光催化降解为模型反应,研究NiO-ZnO纳米复合光催化剂的光催化活性,实验结果表明,p-n结型NiO-ZnO纳米复合光催化剂对Cr6+的光催化还原活性高于商业P-25 TiO2和纯ZnO,但对甲基橙氧化活性却稍低于商业P-25 TiO2。

The NiC2 O4·2H2O-ZnC2O4·2H2O precursor is synthesised by solid state reaction of H2 C2 O4·2H2O with Ni（Ac）2-4H2O and Zn （Ac）2.2H2O. Then the NiO-ZnO nanocomposite with p-n junction is obtained by thermal decomposition of precursor NiC2O4 ·2H2O-ZnC2O4 ·2H2O. The XRD shows that the NiO-ZnO nanocomposite is composed of ZnO with cubic structure and NiO with hexagonal structure after heat treatment in the temperature range of 400 to 800℃. After heat treatment at 500℃ for 2 hours, the mean grain size of NiO and ZnO is 31.7 nm and 17.6 nm respectively. The degradation of methyl orange and Cr6＋ ion is used as model reaction to test the photocatalytic activity of NiO-ZnO photocatalyst. The results show that NiO-ZnO exhibits the higher activity for the photocatalytic reduction of chromium （VI） than commercial P-25 TiO2 and pure ZnO, and the lower activity for the photocatalytic oxidation of methyl orange than commercial P-25 TiO2.