One-step green synthesis of graphene/ZnO nanocomposites for non-enzymatic hydrogen peroxide sensing

In the present study, a disposable electrochemical biosensor for hydrogen peroxide (H₂O₂) was fabricated using a graphene/ZnO nanocomposite-modified screen-printed carbon electrode (SPCE). The adopted method is simple, cost feasible and it avoids the usage of harsh oxidants/acids during the synthesis. Graphite material was subjected to liquid-phase exfoliation with the aid of ultrasonication, without going through the intermediate graphene-oxide phase that can disrupt the pristine structure of the yield. The as-prepared graphene/ZnO nanocomposite was then thoroughly characterized to evaluate its morphology, crystallinity, composition and product purity. All the results clearly indicate that pristine graphene was successfully produced with the graphite exfoliation and ZnO nanoparticles were homogeneously distributed on the graphene sheet, without any severe aggregation. The biosensing capability of the graphene/ZnO nanocomposite-modified SPCE was electrochemically evaluated with cyclic voltammetry (CV) and an amperometric analysis. The resulting electrode is found to exhibit an excellent electrocatalytic activity towards the reduction of H₂O₂. The graphene/ZnO-modified SPCE can detect H₂O₂ in a linear range of 1 mM to 15 mM with a correlation coefficient of 0.9859. The electrode is found to have a high sensitivity, selectivity and superior reproducibility for the non-enzymatic detection of an H₂O₂ compound.