Natural Lemon Extract Assisted Green Synthesis of Spinel Co3O4 Nanoparticles for LPG Gas Sensor Application

A fresh lemon juice-assisted auto-combustion method was implemented for the synthesis of Co3O4 nanoparticles (Co3O4 NPs). The structural, vibrational, optical, and morphological properties of prepared Co3O4 NPs were investigated at 350 degrees C. The effects of lemon juice and heat treatment on the physicochemical properties of Co3O4 nanoparticles were investigated. XRD was used to investigate the structure, lattice constant, and crystallite size of Co3O4 NPs. Heat treatment at 350 degrees C causes the crystallite size to increase from 14.4 nm to 23.7 nm. FT-IR spectroscopy was used to investigate the functional groups and vibrational modes of unheated and heated Co3O4 NPs. Unheated and heated Co3O4 NPs had energy band gaps of 3.14 eV and 3.4 eV, respectively. TEM micrographs of heat-treated Co3O4 NPs confirm the nanoscale range of the particles, which agrees well with the crystallite size determined by XRD. The colloidal stability of Co3O4 NPs has been analyzed through zeta potential values, and the obtained values confirm that the colloidal stability of Co3O4 NPs was influenced by heat treat-ment. LPG based sensor behavior of Co3O4 nanoparticles has been tested with various aspects of sensing pa-rameters. The result shows that the prepared nanoparticles can be a promising sensing material for toxic gases like LPG, CO2 and NH3.