Of Sno <sub> 2 </ Sub> / Cnts Composite Controllable Preparation And Gas Sensing Studies

Gas sensitive materials with good performances and stable properties at room temperature are urgently wanted in industry and widely studied by researchers in gas sensor area. Meso-porous tin oxide nanocrystal is prepared by a hydrothermal method in this paper. With the same method, carbonxylic muliti-walled carbon nanotubes are compound with tin oxide. Different morphologies of SnO₂/CNTs composites are obtained by adjusting the concentration of ethernol water, ratio of reactants and precipitat species. The NO_x gas sensing properties of the composites are investigated. Results show that the gas sensing properties of the composites are related to their morphologies. Possible mechanism is proposed. Based on the experimental data, a theoretical study on the adsorption of NO onto the SnO₂ surface is presented. The conclutions of the theoretical calculation are verified by an experiment.Conductive polyaniline (PANI) and PANI/CNTs are prepared through in-situ polymerization. The diameter of the PANI/CNTs composite can be controlled by changing the mass ratio of reactants. NO_x gas and NH₃ gas sensing tests of the pure PANI and PANI/CNTs composites are carried on.Cu₂O powder and SnO₂/CNTs composites are mixed by grinding and the NO_x gas and NH₃ gas sensing properties of the mixture are studied. A method to promote the selectivity of a sensing material is proposed and shows a possibility to ordinary sensing materials for better use.