合成ZnO纳米阵列及刺突状CuO/ZnO异质结

采用低温水热法在掺氟SnO₂ (FTO)导电玻璃表面制备ZnO纳米阵列, 研究了前驱体溶液浓度摩尔配比对ZnO纳米阵列形貌、光学性能及其生长机理的影响. 研究发现, 随着前驱体溶液浓度摩尔配比的增加, ZnO纳米阵列形貌及光学性能也随之变化. ZnO纳米阵列高度逐渐降低, ZnO纳米阵列直径和光学带隙值大体上出现先增大后降低的趋势. 而当前驱体溶液(Zn(NO₃)₂:环六亚甲基四胺(HMT, C₆H₁₂N₄))浓度摩尔配比为5:5时, 其光学禁带值(3.2 eV)接近于理论值. 结果显示制备ZnO纳米阵列的最优浓度摩尔配比为5:5. 随后选用最优浓度摩尔配比下制备的ZnO纳米阵列为基底, 通过一种两步溶液法成功在其表面制备刺突状CuO/ZnO异质结.从场发射扫描电镜(FE-SEM)结果中可以清楚看见, 大量的CuO纳米粒子沉积在ZnO纳米阵列表面形成刺突状异质结结构.研究发现该CuO/ZnO纳米异质结相对于纯ZnO纳米阵列在紫外光下光催化性能明显增加. 最后, 讨论了CuO/ZnO纳米异质结光催化机理.

Syntheses of ZnO Nano-Arrays and Spike-Shaped CuO/ZnO Heterostructure

A low-temperature hydrothermal route was applied to fabricate ZnO nano-arrays on fluorinated tin oxide (FTO)-coated glass substrates. The effects of the molar ratios of the precursor concentrations on the ZnO nano-arrays were studied with respect to morphology, optical properties, and growth mechanism. The results show that the length reduced with the increased molar ratios of precursor concentrations, and the diameter first increased then decreased. In general, the change of optical band gap followed the same trend as that for the change in diameter. When the molar ratio of precursor concentrations is 5:5, the optical band gap is 3.2 eV, which is similar to the theoretical value at room temperature. We propose that the optimal molar ratio of zinc nitrate (Zn(NO₃)₂) to hexamethylenetetramine (HMT, C₆H₁₂N₄) is 5:5 for the preparation of ZnO nano-arrays. Spike-shaped CuO/ZnO nano-arrays were also successfully synthesized using a two-step solution-system method. Field emission scanning electron microscope (FE-SEM) results show that there were a large number of copper oxide (CuO) nano-particles (NPs) deposited onto the ZnO nano-array surfaces to form spike-shaped structures. The covered CuO NPs exhibited improved photocatalytic properties over pure ZnO nano-arrays under UV irradiation, and the possible photocatalytic mechanism of the CuO/ZnO nano-heterojunction was discussed in detail.