Study On Synthesis, Characterization And Properties Of Porous Co₃O₄

As an important p-type semiconductor material, porous Co3O4 can improve the chemical reaction area including out and inside surface because of the porous structure and the large specific surface area. Nanoporous Co3O4 shows great potential applications in the field of supercapacitors, gas sensor and so on.In this paper, porous Co3O4 was synthesized by solution combustion method and the gas-sensing performances to volatile organic compound vapors were tested. Porous Co3O4 nanosheets were synthesized by homogeneous precipitation method, and the electrochemical properties were studied. The main results are as follows:(1) Synthesis, characterization and gas-sensing performances of porous Co3O4 synthesized by solution combustion methodBy optimizing the experiment conditions, porous Co3O4 was synthesized by solution combustion method. Analytical methods such as XRD, TEM, SEM, XPS and BET were employed to characterize the phase structure, microstructure, surface composition and specific surface area of porous Co3O4, respectively. Its formation mechanism was explored. The gas-sensing performances of the porous Co3O4 for volatile organic compounds (VOCs) were investigated. The results show that the gas response to 1000 ppm n-butanol reaches a maximum of 27.7 at an operating temperature of 120℃, and it is about five times of the Co3O4 particles. The porous Co3O4 also exhibits certain selectivity and response/recovery time.(2) Synthesis, characterization and gas-sensing performances of porous Co3O4 nanosheets synthesized by homogeneous precipitation methodPorous Co3O4 nanosheets were synthesized by homogeneous precipitation method without using any surfactants and template agents. Analytical methods such as XRD, TEM, SEM, XPS and BET were employed to characterize the phase structure, microstructure, surface composition and specific surface area of porous Co3O4 nanosheets, respectively. The formation mechanism was explored.The sensor based on porous Co3O4 nanaosheets was used for detecting VOCs, including ethanol, methanol, acetone, isopropanol, formaldehyde and n-butanol. The results demonstrate that the sensor shows potential for detecting VOCs. The gas sensor based on mesoporous Co3O4 nanosheets shows the highest sensitivity to 300 ppm VOCs at an operating temperature of 100 ℃ than those of Co3O4 materials reported in literature. The gas sensor shows high response values, fast response and recovery times towards VOCs. So, porous Co3O4 nanosheets are considered as promising sensor meterial for detecting VOCs.(3) Synthesis, characterization and electrochemical properties of pure and Cd-Co3O4 porous nanosheets synthesized by homogeneous precipitation methodPure and Cd-Co3O4 porous nanosheets were synthesized by homogeneous precipitation method without using any surfactants and template agents. Analytical methods such as XRD, TEM, SEM, XPS and BET were employed to characterize the phase structure, microstructure, surface composition and specific surface area of porous Co3O4 nanosheets, respectively. A probable formation mechanism was given. The results demonstrate that 5%Cd-Co3O4 porous nanosheets electrode shows the maximum specific capacitance as high as 737 F/g at the current density of 1 A/g, which is 69% higher than that of the undoped porous Co3O4 nanosheets electrode. Furthermore, it has good specific capacitance retention of ca.96% after 1000 continuous charge-discharge cycles. The results indicate that the 5%Cd-Co3O4 porous nanosheets is a promising electroactive material for faradaic supercapacitor.