Electrochemically Reduced Graphene Oxide – Noble Metal Nanoparticles Nanohybrids for Sensitive Enzyme-Free Detection of Hydrogen Peroxide

Abstract

Electrochemically reduced graphene oxide (ERGO) is a versatile material for the electrode modification, which enables modification of the physicochemical properties of the surface by the reduction and reoxidation of oxygen groups. The oxygen functional groups and structural defects of ERGO deposited on a layer of metal nanoparticles facilitate the electron transport and enhance the electrocatalytic properties of the nanoparticles. ERGO layers show moderate-intrinsic electrocatalytic properties towards the electrochemical reduction of hydrogen peroxide. In this contribution, we present studies of ERGO layers on the top of the nanoparticle layer composed of gold nanoparticles stabilized with silicotungstate ligands (Au/SiW12), silver nanoparticles stabilized with silicotungstate ligands (Ag/SiW12), and silver nanoparticles stabilized with phosphomolybdate ions (Ag/PMo12). The nanoparticles are prepared by the reduction of the chloroauric acid or silver nitrate by the partially reduced forms of H4SiW12O40 or H3PMo12O40 acid. The films of nanoparticles are conditioned by the repetitive potential cycling at pH = 6 before the deposition of the graphene oxide (GO) layer. The GO layer is reduced by scanning the potential between − 0.4 and − 1.2 V vs. SCE. Combination of ERGO with Au/SiW12 or Ag/SiW12 nanoparticles results in synergistic enhancement of amperometric responses to hydrogen peroxide. The electrocatalytic current values observed for the NPs-ERGO layers are higher than the sum of the current for the pure NPs layers and the ERGO layer deposited on a glassy carbon electrode. The Ag/PMo12 nanoparticles show poor electrocatalytic currents due to possible formation of aggregate structures. Infrared and Raman spectroscopies are applied to investigate the electrocatalytic layers.