The Preparation、Characterization And The Gas Sensing Properties Of Flower-like Hierarchical SnO₂Structure

In this work, a kind of simple, convenient and efficient synthesis method was explored for synthesizing SnO2low-dimensional structure. A special structure of flower-like SnO2nanorods arrays were synthesized. The effects of various condition factors on the special structure of the hierarchical flower structure were researched. In addition, the hierarchical flower were doped by rare earth. The gas sensitive performance of the hierarchical flower materials before and after doping was studied.In this article, a special structure of SnO2hierarchical flower were synthesized using a substrates-free hydrothermal route. X-ray powder diffraction (XRD) spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscope (HRTEM), raman spectrum and ultraviolet spectrum were employed to characterize the morphology and structure of the resulting SnO2hierarchical flower, respectively. The influence of the various parameters, such as sodium stannate concentration, reaction temperature, reaction time, alcohol concentration on the structure and morphology of the flower-like SnO2nanorods arrays was researched. Finally, the optimum synthesis parameters of the flower-like SnO2hierarchical structure were obtained.Second, hierarchical flower-like structure were doped by rare earth elements (Y and La, Ce, Pr, Eu), and the materials before and after doping rare earth elements were made into heater gas sensor. Then the gas sensitive properties of ten kinds of combustible and toxic gases, including acetone, formaldehyde, methanol, isopropyl alcohol, ammonia, benzene, toluene, xylene,93#gasoline and ethanol were researched.The research results showed that rare earth doping can improve gas sensitivity. After doping rare earth, sensitivity, selectivity, response and recovery time of the sensors were improved. In the aspect of improving heating voltage, rare earth doped can keep lower optimum operating voltage, especially doping with rare earth Y, the optimum operating voltage to ethanol, isopropyl alcohol and formaldehyde were only about3.5V. In the aspect to improve the gas sensitivity, the sensitivity increased with the increase of gas concentration, and until1000ppm, the sensitivity is still not reached saturation state. Among them, each of the optimal doping amount of rare earth elements is very different. Rare earth Ce and Pr doping,3%concentration of doping amount show the excellent performance of gas sensitive, such as,4V working voltage,3%concentration of doping rare earth Ce on concentration of1000ppm, the sensitivity to isopropyl alcohol and acetone are aboVe600, and the best gas sensitive performance dopped by rare earth Y, La and Eu is5%concentration. In the aspect of improving the response and recovery time, doped with rare earth Ce, the response and recovery to acetone is good; after doping rare earth Pr, the response and recovery to ethanol and formaldehyde is good, doping with rare earth Y, the response and recovery to methanol, ethanol and isopropanol is good, doping with rare earth La, the response and recovery to ethanol and acetone is good, doped with rare earth Eu, the response and recovery to methanol and isopropanol is good.