Nanostructured Ce/CeO2-rGO: Highly Sensitive and Selective Electrochemical Hydrogen Sulfide (H2S) Sensor

Abstract

Herein, cerium/cerium oxide nanoparticles have been decorated on reduced graphene oxide (Ce/CeO₂-rGO) for room temperature electrochemical determination of H₂S in 0.5 M KOH. There is a superior linear correlation between the peak current density and H₂S content in the tested range of 1–5 ppm. Moreover, comparison to other abundant gases such as CO₂ shows no response at the potential of H₂S oxidation, confirming no interference with H₂S detection. It also reveals that the Ce/CeO₂-rGO nanocomposite is a highly selective and sensitive system for the determination of H₂S gas. Ce/CeO₂-rGO synthesized by a simple chemical approach and further characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), field emission-scanning electron microscopy (FE-SEM), coupled energy dispersive analysis of X-ray (EDAX), and BET-surface area measurement confirms the porosity of synthesized nanomaterials and homogeneous decoration of Ce/CeO₂ nanoparticles on rGO sheets. The electrochemical studies, i.e., linear sweep voltammetry (LSV), of Ce/CeO₂-rGO demonstrate the electrochemical H₂S sensing at room temperature and for lower gas concentration (1 ppm) detection. The sensing mechanism is believed to be based on the modulation of the current and applied potential path across the electron exchange between the cerium oxide and rGO sites when exposed to H₂S.

Graphical Abstract

One-pot synthesis of Ce/CeO₂-GO hybrid nanostructure is of immense significance for H₂S gas sensors. Here is a new superficial synthetic way intended for the synthesis of Ce/CeO₂-GO nanocomposites through the sol–gel technique. Herein, we depict that the consequential Ce/CeO₂ NPs decorated on graphene oxide sheet material can give competent electrocatalysts for the H₂S oxidation reaction in an alkaline condition. The current density of 5.9 mA/cm² on the tiny potential of 2.5 mV vs. SCE demonstrates huge catalytic bustle and stability.