Influence of reduced graphene oxide layer on sensing characteristics of Co3O4/rGO nanocomposite towards Liquefied Petroleum Gas (LPG)

Abstract

Liquefied petroleum gas (LPG), a mixture of different hydrocarbons, is a highly inflammable and explosive gas that is harmful to the environment and human health. Thus, it is imperative to fabricate LPG sensors with higher sensitivity, selectivity, stability, and minimal power consumption, functioning at low temperatures. The current study reports on the monitoring and detection of LPG at low functional temperatures using Co3O4-loaded on rGO (rGO-Co) prepared using the hydrothermal method. The microstructural properties of the materials were investigated in detail. The rGO-Co (80 wt%) sensor showed outstanding sensitivity (0.00364 ppm−1) and selectivity toward LPG, as well as a limit of detection of 1 ppm at a temperature of 125 °C. The sensing mechanism showed that an even distribution of Co3O4 throughout the rGO layers, serving as efficient sites for the adsorption and desorption of LPG molecules, was associated with enhanced gas-sensing capabilities. Furthermore, the response to LPG detection was significantly influenced by the combination of the finite spherical nanoparticles with increased pore sizes between them and reduced energy band gaps. Thus, the novel improvement of the sensor towards LPG detection was linked to the ohmic connection formed between rGO and Co3O4 forming a p-p heterojunction at the interface. Additionally, the coupling of Co-O-C bonds validated by high-temperature X-ray diffraction and X-ray photoelectron spectroscopy provided extra active sites from Co3+ for effective LPG adsorption. The sensing mechanism induced by the loading of Co3O4 on the rGO surface was also deliberated.