Electrochemically reduced graphene oxide on gold nanoparticles modified with a polyoxomolybdate film. Highly sensitive non-enzymatic electrochemical detection of H^sub 2^O^sub 2

• Published in: Sensors and actuators. B, Chemical Chemical, 2018-04, Vol.258, p.745
• Main Authors: Berbec, S, Zoladek, S, Jablonska, A, Palys, B
• Format: Article
• Language: English
• Subjects: Buffer solutions; Conditioning; Cycles; Electrocatalysis; Electrochemical analysis; Electrodes; Glassy carbon; Gold; Graphene; Hydrogen peroxide; Nanoparticles; Raman spectra; Sensitivity; Sensors; Silver chloride; Synergistic effect
• ISSN: 0925-4005; 1873-3077

Gold 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 −0.4 V 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 −1.2 V 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−1 cm‐2 (limit of detection is equal to 56 nM) for the H2O2concentration lower than 0.1 mM, and 381.5 μA mM−1 cm‐2 at 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.