Highly improved toluene gas-sensing performance of mesoporous Co₃O₄ nanowires and physical mechanism

Mesoporous Co3O4 nanowires were synthesized with the nanocasting method, and then the dispersed Co3O4 nanowires (Co3O4-DNWs) were separated from the bundled Co3O4 nanowires (Co3O4-BNWs) by the centrifugation technique. From the characterization with TEM, X-ray diffraction, UV-vis spectra and nitrogen adsorption-desorption isotherm, both samples present the same mesoporous-structure, diameter and the similar defects due to the same synthesis conditions. All results indicate that the microstructures and morphology of Co3O4 nanowires greatly affect the toluene gas sensing performance. Owing to the mesoporous-structures with the high surface area, the sensitivities of both samples are higher than others'. Co3O4-DNWs exhibit the higher specific surface area (44.98 m(2) g(-1)) than Co3O4-BNWs, leading to the excellent gas-sensing properties to toluene gas at the optimized operating temperature of 210 degrees C. Moreover, both samples present the excellent stability and selectivity to toluene gas. The gas-sensing mechanism results from the surface oxygen and toluene gas adsorption through comparing the sensitivity of Co3O4-DNWs and Co3O4-BNWs.