Anhui Key Laboratory of Advanced Building Materials, Key Laboratory of Functional Molecule Design and Interface Process, School of Materials and Chemical Engineering, Anhui Jianzhu University , Hefei, 230601, P. R. China.
Department of Chemical Engineering, Monash University , Clayton, Victoria 3800, Australia.
ACS Appl Mater Interfaces. 2016 Apr 13;8(14):9080-7. doi: 10.1021/acsami.6b00028. Epub 2016 Mar 29.
To selectively remove heavy metal from dye solution, inspired by the unique pore structure of ZIF-8, we developed a synthetic strategy for rapid construction of ZnO@ZIF-8 heterostructure photocatalyst for selective reduction of Cr(VI) between Cr(VI) and methylene blue (MB). In particular, ZnO@ZIF-8 core-shell heterostructures were prepared by in situ ZIF-8 crystal growth using ZnO colloidal spheres as template and zinc source within 8-60 min. The shell of the resulting ZnO@ZIF-8 core-shell heterostructure with a uniform thickness of around 30 nm is composed of ZIF-8 crystal polyhedrons. The concentration of organic ligand 2-methylimidazole (Hmim) was found to be crucial for the formation of ZnO@ZIF-8 core-shell heterostructures. Different structures, ZnO@ZIF-8 core-shell spheres and separate ZIF-8 polyhedrons could be formed by altering Hmim concentration, which significantly influences the balance between rate of Zn(2+) release from ZnO and coordinate rate. Importantly, such ZnO@ZIF-8 core-shell heterostructures exhibit size-selective photocatalysis properties due to selective adsorption and permeation effect of ZIF-8 shell. The as-synthesized ZnO@ZIF-8 heterostructures exhibited enhanced selective reduction of Cr(VI) between Cr(VI) and MB, which may find application in the dye industry. This work not only provides a general route for rapid fabrication of such core-shell heterostructures but also illustrates a strategy for selectively enhanced photocatalysis performance by utilizing adsorption and size selectivity of ZIF-8 shell.
为了从染料溶液中选择性地去除重金属，受 ZIF-8 独特的孔结构的启发，我们开发了一种快速构建 ZnO@ZIF-8 异质结构光催化剂的合成策略，用于在 Cr(VI) 和亚甲基蓝 (MB) 之间选择性还原 Cr(VI)。具体而言，通过在 8-60 分钟内使用 ZnO 胶体球作为模板和锌源原位生长 ZIF-8 晶体，制备了 ZnO@ZIF-8 核壳异质结构。所得 ZnO@ZIF-8 核壳异质结构的壳厚约为 30nm，由 ZIF-8 晶体多面体组成。发现有机配体 2-甲基咪唑 (Hmim) 的浓度对于形成 ZnO@ZIF-8 核壳异质结构至关重要。通过改变 Hmim 浓度可以形成不同的结构，如 ZnO@ZIF-8 核壳球体和分离的 ZIF-8 多面体，这显著影响了从 ZnO 释放 Zn(2+)的速率和配位速率之间的平衡。重要的是，由于 ZIF-8 壳的选择性吸附和渗透作用，这种 ZnO@ZIF-8 核壳异质结构表现出尺寸选择性的光催化性能。所合成的 ZnO@ZIF-8 异质结构表现出增强的 Cr(VI)和 MB 之间的选择性还原性能，这可能在染料工业中得到应用。这项工作不仅提供了一种快速制备这种核壳异质结构的一般途径，而且还说明了利用 ZIF-8 壳的吸附和尺寸选择性来增强光催化性能的策略。
