Electrochemically reduced graphene oxide on gold nanoparticles modified with a polyoxomolybdate film. Highly sensitive non-enzymatic electrochemical detection of H_2O_2

摘要

Graphical abstractDisplay OmittedHighlights•Gold nanoparticles stabilized with PMo12 were hydrolyzed by potential cycling in the −0.3÷0.4V vs. SCE range at pH=6.•Hydrolysis products including MoO42−monomer remain attached to nanoparticles.•Electrochemically reduced graphene oxide (ERGO) on the gold nanoparticles layer show very high sensitivity to H2O2.•Structure of ERGO on AuNPs contains numerous defects contributing to the electrocatalytic activity.AbstractGold nanoparticles (AuNPs) were prepared via the chloroauric acidreduction using Keggin-type anions (PMo12O403−). The layer of AuNPs was deposited on the glassy carbon electrode (GC) and conditioned using repetitive potential cycling between 0.3 and −0.4V vs. SCE in the buffer solution at pH=6. The changes in the polyoxometalate structure upon cycling are studied using Raman spectra. Graphene oxide (GO) was drop-cast on a thin layer of AuNPs on a GC electrode. Then, GO was reduced by scanning the electrode potential between −0.4 and −1.2V vs. Ag/AgCl. The resulting layer of the electrochemically reduced graphene oxide(ERGO) on AuNPs shows non-enzymatic sensitivity to hydrogen peroxide. The sensitivity of the ERGO/AuNPs/GC/electrode to H2O2equals 741 mA mM−1cm‐2(limit of detection is equal to 56nM) for the H2O2concentration lower than 0.1mM, and 381.5 μA mM−1cm‐2at the higher concentration of H2O2. The electrocatalytic activity of the bare AuNPs layer and the activity of ERGO deposited directly on the GC electrode are significantly lower, which pointing to a synergistic effect between ERGO and AuNPs. The electrodes are characterized using Raman spectra. The mechanism of the ERGO-AuNPs synergistic electrocatalysis is proposed.