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.

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Fe-MIL-101-NH(2) was prepared by a novel method. The MOFs adhered well to SPPO via chemical bonds, and yielded the mixed-matrix Fe-MIL-101-NH(2)-SPPO membrane for use in fuel cells. The proton conductivity of the membranes was as high as 0.10 S cm(-1) at room temperature and 0.25 S cm(-1) at 90 °C.

Novel anion exchange membranes (AEMs), based on poly(phenylene oxide) (PPO) chains linked to pendant 1,2-dimethylimidazolium (DIm) functional groups, have been prepared for evaluation in alkaline polymer electrolyte membrane fuel cells (APEFCs). Successful functionalisation of the PPO chains was confirmed using H-NMR and FT-IR spectroscopies. The ionic conductivities of the resulting DIm-PPO AEMs at 30 °C are in the ranges of 10-40 mS cm and 18-75 mS cm at 60 °C. The high ionic conductivities are attributed to the highly developed microstructures of the membranes, which feature well-defined and interconnected ionic channels (confirmed by atomic force microscopy, AFM, measurements). Promisingly, the ion-exchange capacities (IECs) of the DIm-PPO AEM are maintained after immersion in an aqueous KOH solution (2 mol dm) for 219 h at 25 °C; a previously developed monomethyl imidazolium PPO analogue AEM (Im-PPO) showed a significant decline in IEC on similar treatment. This reduction in undesirable attack by the OH conducting anions is ascribed to an increase in steric interference and removal of the acidic C2 proton [in the monomethyl Im-groups] by the methyl group in the DIm cationic ring. Moreover, the maximum power densities produced in simple beginning-of-life single cell H /O fuel cell tests increased from 30 mW cm to 56 mW cm when switching from the Im-PPO AEM (fuel cell temperature = 50 °C) to the DIm-PPO-0.54 AEM (fuel cell temperature = 35 °C) respectively (even with the use of lower temperatures). This journal is © The Royal Society of Chemistry 2013

Ultrathin ZIF-8 membranes with a thickness of around 200 nm were prepared by chemical vapour modification of surface chemistry and nanopores of an asymmetric bromomethylated poly(2,6-dimethyl-1,4-phenylene oxide) (BPPO) substrate. The resulting ZIF-8 membranes exhibited exceptional H2 permeance as high as 2.05 × 10(-6) mol m(-2) s(-1) Pa(-1) with high H2/N2 and H2/CO2 selectivities (9.7 and 12.8, respectively).