Removal and reutilization of metal ions on ZIF-67/GO membrane via synergistic photocatalytic-photothermal route

The serious problem from pollution of metal ions placed great pressure to global water ecosystem and human beings. Herein, a synergistic photocatalytic-photothermal system of integrated membrane for the removal and reutilization of aqueous Ag+ ions was designed. The crystal of zeolitic imidazolate frameworks-67 (ZIF-67) stably grew on the graphene oxide (GO) membrane with the uniform distribution. In the ZIF-67/GO membrane, the adsorption and photo-reduction of Ag+ ions on ZIF-67 crystals led to the deposition of Ag nanoparticles on the membrane surface, which facilitated the capture of visible light, suppressed the recombination of the electron-hole pairs and promoted the photothermal effect. Meanwhile, the high efficiency of photothermal conversion on GO substrate realized the water evaporation to concentrate the Ag+ solution and inhibited the separation of photo-induced charges. The synergistic photocatalytic-photothermal route on ZIF-67/GO membrane provides a new sight for the recycle of metal ions for the future practical applications.