In situ Immobilization of Copper Nanoparticles on Polydopamine Coated Graphene Oxide for H2O2 Determination

Nanostructured electrochemical sensors often suffer from irreversible aggregation and poor adhesion to the supporting materials, resulting in reduced sensitivity and selectivity over time. We describe a versatile method for fabrication of a H2O2 sensor by immobilizing copper nanoparticles (Cu NPs; 20 nm) on graphene oxide (GO) sheets via in-situ reduction of copper(II) on a polydopamine (PDA) coating on a glassy carbon electrode. The PDA film with its amino groups and catechol groups acts as both a reductant and an adhesive that warrants tight bonding between the Cu NPs and the support. The modified electrode, best operated at a working voltage of -0.4 V (vs. Ag/AgCl), has a linear response to H2O2 in the 5 μM to 12 mM concentration range, a sensitivity of 141.54 μA∙mM‾1∙cm‾2, a response time of 4 s, and a 1.4 μM detection limit (at an S/N ratio of 3). The sensor is highly reproducible and selective (with minimal interference to ascorbic acid and uric acid). The method was applied to the determination of H2O2 in sterilant by the standard addition method and gave recoveries between 97% and 99%.