Synthesis And Gas-sensing Property Of Nanosized Stannic Oxide

The environmental security catches people’s eyes widely with the development of science and the progress of the society, thus it is important to detect toxic and flammable gas. Metal oxide semiconductor SnO2 is a kind of important functional materials, which are widely used in solar cells, photocatalysis, gas sensors and other fields due to its excellent physical and chemical properties. It is well known that the gas sensing properties of SnO2 strongly depend on the structure of nanomaterials (the specific surface area, dimension and pore structure), morphology, particle size and the types of metal dopants, etc. The contemporary research reports shows that tin dioxide sensitive materials are mainly used in the detection of ethanol, acetone, formaldehyde, acetaldehyde, etc. However, there are many problems still exsit, such as lower selectivity, poorer stability and higher operating temperature. Therefore, the manufacture of nanosize tin dioxide gas sensitive material of excellent capability has important practical significance for environmental protection and human health. Based on this,the tin oxide nanomaterials were prepared by hydrothermal method, and carried out in-situ modification, then we will investigate their gas sensing properties for different volatile organic compounds. Major researchs and conclusions have been summarized as follows:1. The controlled-morphology hexagonal brick-shaped nano-SnO2 was synthesized by adjusting hydrothermal time using o-phthalic acid and tin tetrachloride as raw materials, which could effectively detect low-concentration triethylamine at low temperature.2. Ni-dropped SnO2 was prepared by hydrothermal methods and the contents of dopant were selected for optimizing reaction conditions. XRD reveals that Ni2+was substituted into some of Sn4+sites in the process of doping. Compared to undoped SnO2, Ni-doped samples exhibit reduced crystallinity. Among them,12 wt.% Ni-doped SnO2 shows maximum sensitivity, fastest response and recovery time and best stability and reproducibility to triethylamine.3. The Ce-doped SnO2 was prepared by hydrothermal methods and the triethylamine gas-sensing properties were tested. The results showed that Ce-doped could inhibited the growth of SnO2 grains and enhanced the sensitivity.4. Tin dioxide nanoparticles were prepared by hydrothermal reaction using stannic chloride pentahydrate and hydrazine hydrate (HHA) as raw material, and through control of dosage of HHA to achieve accurate detection of ethanol. The sensor fabricated from 10mL HHA showed the highest response to ethanol.when hydrazine hydrate was 10 ml. The sensitivity reached 12 when the sensor was exposed to lppm ethanol, and the response time and recovery time were about 1 and 40s, respectively.5. Tin oxide nanoparticles were prepared using stannic chloride and terephthalic acid as feedstock under change the pH of the solution,respectively. The results indicated that they have diverse sensitive characteristics under different preparation conditions. The optimum working temperature is 260℃ at larger PH value, while smaller PH value is 200℃. And in the best working temperature, larger PH value for preparation of nanometer SnO2 gas-sensing properties superior to the smaller PH value at various acetone concentration.