Electrochemical Hydrogen Gas Sensing Employing Palladium Oxide/Reduced Graphene Oxide (PdO-rGO) Nanocomposites

Abstract

This research work aims at proposing cheap, facile, sensitive, and selective assembly of three electrode electrochemical hydrogen (H2) gas sensor which operates on room temperature in ambient conditions. Palladium oxide-reduced graphene oxide (PdO-rGO) nanocomposite have been synthesized using insitu chemical sol-gel method and modified Hummer’s method. The phase, structure, particle size, and bonding information have been obtained using X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), Fourier Transform Infrared (FTIR) spectroscopy, and Ultraviolet-Visible (UV-Vis) absorption spectroscopy. Palladium oxide (PdO) nanoparticles of size ranging from 30 to 35 nm have been successfully attached with uniform 2D network of reduced graphene oxide (rGO) sheets which offers a large surface area for H2 adsorption. The thin film of nanocomposite have been fabricated on conducting Indium tin oxide (ITO) glass substrates using electrophoretic deposition (EPD) process and is employed as working electrode (WE) in indigenously developed three-electrode cell. Thin film surface morphology have been observed using Scanning Electron Microscopy (SEM) and it shows agglomerates of PdO nanoparticles with multiple randomly stacked rGO nanosheets uniformly spread across the surface of the film. The amperometric response of the assembled electrochemical sensor has been recorded for the detection of 10 to 80 percent concentration of hydrogen gas using potentiostat/galvanostat autolab. The sensitivity of the sensor is found out to be $0.462~ \\mu \\text{A}$ /% H2 concentration and sensing calibration curve shows a uniform linear response. The stability and selectivity of the sensor has been enhanced using H2 insensitive reference electrode (RE) and solid polymer electrolyte gas permeable membrane, respectively, which will aid new dimensions in designing robust H2 sensor at room temperature.