Palladium Nanoparticles Embedded into Graphene Nanosheets: Preparation, Characterization, and Nonenzymatic Electrochemical Detection of H2O2.

A novel nonenzymatic H₂O₂ sensor based on a palladium nanoparticles/graphene (Pd-NPs/GN) hybrid nanostructures composite film modified glassy carbon electrode (GCE) was reported. The composites of graphene (GN) decorated with Pd nanoparticles have been prepared by simultaneously reducing graphite oxide (GO) and K₂PdCl₄ in one pot. The Pd-NPs were intended to enlarge the interplanar spacing of graphene nanosheets and were well dispersed on the surface or completely embedded into few-layer GN, which maintain their high surface area and prevent GN from aggregating. XPS analysis indicated that the surface Pd atoms are negatively charged, favoring the reduction process of H₂O₂. Moreover, the Pd-NPs/GN/GCE could remarkably decrease the overpotential and enhance the electron-transfer rate due to the good contact between Pd-NPs and GN sheets, and Pd-NPs have high catalytical effect for H₂O₂ reduction. Amperometric measurements allow observation of the electrochemical reduction of H₂O₂ at 0.5 V (vs. Ag/AgCl). The H₂O₂ reduction current is linear to its concentration in the range from 1×10⁻⁹ to 2×10⁻³ M, and the detection limit was found to be 2×10⁻¹⁰ M ( S/ N=3). The as-prepared nonenzymatic H₂O₂ sensor exhibits excellent repeatability, selectivity and long-term stability. [ABSTRACT FROM AUTHOR]