ZnO is an important n-type semiconductor sensing material. Currently, much attention has been attracted to finding an effective method to prepare ZnO nanomaterials with high sensing sensitivity and excellent selectivity. A three-dimensionally ordered macroporous (3DOM) ZnO nanostructure with a large surface area is beneficial to gas and electron transfer, which can enhance the gas sensitivity of ZnO. Indium (In) doping is an effective way to improve the sensing properties of ZnO. In this paper, In-doped 3DOM ZnO with enhanced sensitivity and selectivity has been synthesized by using a colloidal crystal templating method. The 3DOM ZnO with 5 at. % of In-doping exhibits the highest sensitivity (∼88) to 100 ppm ethanol at 250 °C, which is approximately 3 times higher than that of pure 3DOM ZnO. The huge improvement to the sensitivity to ethanol was attributed to the increase in the surface area and the electron carrier concentration. The doping by In introduces more electrons into the matrix, which is helpful for increasing the amount of adsorbed oxygen, leading to high sensitivity. The In-doped 3DOM ZnO is a promising material for a new type of ethanol sensor.

ZnO nanopyramids (NPys) with exposed crystal facets of {101̅1} were synthesized via a one-step solvothermal method, having a uniform size with a hexagonal edge length of ∼100 nm and a height of ∼200 nm. Technologies of XRD, TEM, HRTEM, Raman, PL, and XPS were used to characterize the morphological and structural properties of the products, while the corresponding gas sensing properties were determined by using ethanol as the target gas. For the overall goal of defect engineering, the effect of aging temperature on the gas sensing performance of the ZnO NPys was studied. The test results showed that, at the aging temperature of 300 °C, the gas sensing property has been improved to the best, with the fast response-recovery time and the excellent selectivity, because the ZnO300 has the most electron donors for absorbing the largest content of O(2-). Model of defect redistribution was used to explicate the changing of the surface defects at different aging temperatures. The findings showed that, in addition to VO, Zni was the dominant defect of the {101̅1} crystal facet. The gas sensing performance of the ZnO NPys was determined by the contents of VO and Zni, with all of the defects redistributed on the surface. All of the results will be noticeable for the improvement of the sensing performance of materials with special crystal facet exposing.

No abstract

No abstract

No abstract