In situ assembly of ZnO/graphene oxide on synthetic molecular receptors: Towards selective photoreduction of Cr(VI) via interfacial synergistic catalysis

Designing a novel type of imprinted photocatalysts for selective photoreduction of highly toxic pollutants is extremely needed in semiconductor photocatalysis. In this work, imprinted photocatalysts (named ZnO/GO-MIPs) were synthesized via Pickering emulsion polymerization by in situ assembling ZnO/GO composites on the synthetic molecular receptors (MIPs). The experimental data showed that the ZnO/GO-MIPs owned specific affinity towards the target Cr(VI) in aqueous solution with an imprinting factor ( IF ) of 1.6. Under the illumination of visible light, the ZnO/GO composites could selectively photoreduce the Cr(VI) adsorbed by the MIPs. In comparison with the ZnO/GO catalysts under light illumination, the ZnO/GO-MIPs showed a 15 fold increase in photoreduction of Cr(VI). Mechanism study indicates the photoreduction of Cr(VI) by the ZnO/GO composites was occurred at the interface between the solid MIP core and the aqueous solution. Compared to the ZnO-MIPs and the GO-MIPs, the ZnO/GO-MIPs clearly showed interfacial synergistic catalysis effect. To the best of our knowledge, this is first time that selective photoreduction of highly toxic pollutants at the solid-water interface by the ZnO/GO-MIPs was achieved. We believe the ZnO/GO-MIP catalysts have great potential in interfacial synergistic catalysis in environment and catalysis fields.