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Cobalt oxide (Co₃O₄) nanostructures co-doped with 5 wt%, 10 wt%, and 15 wt% NiZn were synthesized via the hydrothermal method. Structural analysis using X-ray diffraction (XRD) confirmed the formation of a pure spinel phase without any secondary peaks. The crystallite size increased from 19 nm to 48 nm with increasing dopant concentration. High-resolution transmission electron microscopy (HRTEM) further verified the spinel structure, revealing lattice spacings (d-spacing) in the range of 0.2305–0.4477 nm, while selected area electron diffraction (SAED) patterns showed a prominent (311) diffraction ring. UV–Vis spectroscopy indicated a decrease in band gap energy with increasing NiZn doping concentration. Scanning electron microscopy (SEM) images revealed predominantly spherical nanoparticles. Gas sensing studies demonstrated that the 15 wt% NiZn-doped Co₃O₄ sensor exhibited the highest sensitivity toward liquefied petroleum gas (LPG) at a relatively low operating temperature of 75 °C. Furthermore, the sensor displayed good selectivity, repeatability, and long-term stability.
Keywords:Gas sensor,Co3O4,LPG,NiZn and co-doped