Electrochemical Reduction-assisted in situ Fabrication of Graphene/Au Nanoparticles@polyoxometalate Nanohybrids film： High Performance Electrochemical Detection for Uric Acid.

Nanohybrid films had attracted much attention owning to the enhancement of catalytic activity. However, the fabrication time took hours to days, no matter if it was the preparation of nanohybrids or the assembly process. Furthermore, the catalytic efficiency of the nanohybrid film still remained to improve. In this paper, a reduced graphene oxide (rGO)/gold nanoparticles (Au NPs)@polyoxometalate (POM) nanohybrid film was successfully fabricated by combining electrodeposition and electrochemical reduction in situ processes. The assembly process involving no organic or polymer linker molecules [except for a precursor poly­(ethylenimine) (PEI) coating for indium tin oxide (ITO)] can be completed within 1 h. The reduced POM K6[P2W18O62]·19H2O (P2W18) was employed as reducing agents and bridging molecules for rGO and Au nanoparticles and the encapsulating molecules for the Au nanoparticles. The most interesting one is the {rGO/Au@P2W18} modified electrode loading only the monolayer catalyst of Au@P2W18 and exhibiting comparable, even better electrochemical detection performance toward uric acid than other sensors with three to eight layers of the catalyst. The amperometric detection displayed a great sensitivity, lower detection limit, wide linear range, good long-time stability, superior selectivity, and reproducibility. The enhanced catalytic property may attribute to the improved conductivity of the film without organic or polymer linker molecules (except for a precursor PEI coating) and the electron transfer in the process of film fabrication.