Factors Influencing the Electrocatalytic Properties of Graphene Oxide – Gold Nanoparticles Hybrid System

Abstract

AbstractGraphene oxide (GO) – gold nanoparticles (AuNPs) nanocomposites are promising materials for H2O2 electrochemical sensors. Surface composition of GO is an important factor influencing the sensitivity. In this study GO has been mildly reduced by ammonia (GO‐NH3) or sodium hydroxide solution (GO‐NaOH). Such mild reduction opens up the epoxide groups on the GO surface but not the other oxygen functionalities. The electrochemical reduction of GO has been carried out too. It is found that the structure of the electrochemically reduced graphene oxide (ERGO) depends on the concentration of GO used to prepare the layer. For concentrated GO (10 mg/ml) the electro‐reduction leaves OH surface groups while for lower concentrations all surface groups can be removed. All GO materials listed above were combined with AuNPs and examined as possible amperometric H2O2 sensors. The two types of layers were examined: AuNPs deposited on the top of the GO material or AuNPs deposited under the GO material layer. Among studied composites ERGO obtained from 5 mg/ml GO on the AuNPs layer showed the highest sensitivity (155.6 μA cm−2 mM−1 at −0.4 V vs Ag/AgCl).