N-Doped Porous Graphene Film Decorated with Palladium Nanoparticles for Enhanced Electrochemical Detection of Hydrogen Peroxide

Abstract

Graphene film has excellent electrical conductivity and flexibility, with which it can be used as a versatile substrate to load active species to construct free-standing electrochemical sensors. In this work, Pd nanoparticle-decorated N-doped porous graphene film (Pd/NPGF) was prepared by a simple and mild strategy to enhance the electrochemical behavior of graphene film-based free-standing electrodes. The morphological structure and surface component of the Pd/NPGF were characterized by scanning electron microscopy, transmission electron microscopy, Raman spectra and X-ray photoelectron spectroscopy measurements. The results revealed that the Pd/NPGF contained abundant pores and uniformly dispersed Pd nanoparticles, which could bring a favorable electrochemical response. Due to the synergetic effects of abundant pores, uniform Pd nanoparticles and the substitutional doping of the graphene framework with N, the novel free-standing Pd/NPGF electrode provides a high active site exposure, a high specific area and fast electron/mass diffusion during electrochemical reactions. Considering the favorable flexibility and excellent electrical conductivity of Pd/NPGF, we selected hydrogen peroxide, a significant biomarker, as a model to investigate its electrochemical performance in neutral conditions. The electrochemical biosensor based on the Pd/NPGF electrode exhibited enhanced activity relative to the NPGF and porous graphene film (PGF) with different concentrations of H2O2. The Pd/NPGF electrode displayed a high sensitivity (176.7 μA·mM−1·cm−2), a large linear range from 5 μM to 36.3 mM, a low limit of detection (LOD) of 2.3 μM, excellent stability and a short response time, all of which qualify the Pd/NPGF electrode for a promising sensor for H2O2 sensing.