荷叶状ZnS@ZnO异质纳米结构阵列的构筑及其对H2S的气敏性能研究

Hydrogen sulphide (H2S) is a toxic gas, which could cause serious health or environment problems even at a low concentration. There remain some disadvantages of gas sensors based on semiconducting oxides for H2S detection, mainly sensing poisoning and low sensitivity. This application aims to improve the sensitivity and stability of sensor for detecting low concentration H2S by constructing a lotus leaf-like ZnS@ZnO heterogeneous nanostructure. This novel nanostructure is able to provide a large effective surface-to-volume ratio and a heterojunction region, which are thought to be beneficial to improving sensitivity of materials. Moreover, ZnS layer on ZnO nanostructure is capable of preventing the spontaneous reaction between ZnO and H2S. The as-prepared lotus leaf-like ZnO nanostructure in our previous work is used as precursor. The formation of ZnS@ZnO heterogenous structures are controlled by the difference activity of ZnO crystal planes and growth condition. Subsequently, we fabricate gas sensors with as-prepared samples and test their H2S gas sensing properties. Then, we study the sensing mechanism of ZnS@ZnO heterogenous structures by characteristizing their carrier concentration and work function et. al. This project is helpful to develop new-type gas sensor for detecting other corrosive gases.

H2S是一种常见的有害气体，非常低的浓度便会引发严重的健康和环境问题。如何灵敏便利地监测环境中H2S的浓度成为目前具有挑战性的研究课题。本项目针对氧化物半导体基H2S气敏材料存在的易中毒、难以稳定地灵敏响应等不足，提出利用荷叶状ZnS@ZnO异质纳米结构阵列来构筑H2S气敏元件的学术思想：利用纳米叶片大的比表面积及异质结构效应来提高灵敏度，利用异质结构中ZnS层对ZnO的有效保护来促进稳定性。我们拟使用前期工作已获得的荷叶状ZnO纳米结构作为前驱体，利用ZnO不同晶面的活性差异来制备荷叶状ZnS@ZnO异质纳米结构，通过控制生长液的过饱和度来调控异质结构中ZnS层的形成及厚度尺寸；研究不同结构特点的荷叶状ZnS@ZnO异质纳米结构对H2S的气敏性能，探讨其增强气敏性能的作用机制；评价其作为气敏器件监测环境中H2S浓度的可行性。相关研究和探索有望为发展监测腐蚀性有害气体的气敏器件提供新思路。

本研究工作为了对环境中低浓度有害气体H2S实现灵敏检测，进行了气敏材料开发与器件制备。实现了对ZnO纳米棒、纳米片及其复合结构的尺寸调控。通过液相法和气固相反应法，实现了ZnO基核壳异质结构,的制备,如ZnO@SiO2, ZnO@ZnS&Au等。所得复合纳米材料在室温工作温度下可以实现对0.01-1 ppm浓度范围H2S气体的灵敏、可重复地检测，实现了预期目标。通过密度泛函理论对所得异质纳米结构表面氧气吸附能与电子分布情况进行了计算，所得结果对材料气敏性能的提高进行了合理地解释。相关研究探索，为发展监测腐蚀性有害气体气敏器件提供了新思路。在此工作基础上，我们将ZnO/ZnS二维纳米片的设计与合成方法拓展到其它二维片状纳米材料中，成功合成了新型二维片状纳米材料，如SnS2,In2Se3,NiCo2O4，并开发了所得材料在催化降解CO2与超疏水抗冰方面的性能应用。