具有高活性晶面In2O3纳米晶的控制性制备及其气敏增强机制研究

In this project, In(OH)3 and InOOH nanostructures with different morphologies and exposed facets will be prepared via the hydrothermal or solvothermal method based on the selective adsorption of various organic and inorganic complexing agents. Then, In2O3 nanocrystals with different exposed facets will be obtained by calcining the as-prepared In(OH)3 and InOOH precursors. The surface atomic arrangement on the exposed facet of In(OH)3, InOOH 和In2O3 nanostrucures will be studied by software simulation and Density Functional Theoretic (DFT) calculation to reveal the formation mechanism of the In(OH)3 and InOOH nanostructures with different morphologies and the structural correlation between the In2O3 nanocrystals and their In(OH)3, InOOH precursors. Certain highly reactive facets will be found by investigating the gas-sensing performance of In2O3 nanocrystals with different exposed facets to various kinds of combustible, explosive and toxic gas or vapor, such as H2, C2H5OH, CO and HCHO. Theoretical model of In2O3 exposed facets will be built by using the simulation softwares, such as Materials Studio (MS) and Vienna Ab-initio Simulation Package (VASP). By employing the Density Functional Theory, the coordinate bonds, unsaturated bonds and the charge distribution of the In atoms on the In2O3 exposed facets will be confirmed by the, the adsorption and chemical reaction with target gas of molecular oxygen species on different In2O3 exposed facets will be studied, the intrinsic causes of the highly reactive facet enhanced gas-sensing properties will be revealed. The planned research work in the project will provide theoretic and technological support to the development of high-performance gas-sensing materials.

本项目基于配位剂在结构匹配晶面上的选择性吸附，采用水热/溶剂热法首先制备暴露不同晶面的In(OH)3、InOOH纳米结构；再经煅烧处理得到具有不同晶面的In2O3纳米晶。借助软件模拟及密度泛函理论计算，研究 In(OH)3、InOOH 和In2O3纳米材料暴露晶面的原子结构，揭示不同形貌In(OH)3、InOOH的形成机理及其与煅烧所得In2O3的结构关联性。研究所制备的具有不同晶面的In2O3纳米晶对H2、C2H5OH、CO、HCHO等易燃、易爆和有毒气体的响应特性，发现In2O3高活性晶面。利用MS以及VASP等模拟软件构建In2O3高活性晶面的理论模型，采用密度泛函理论确定暴露晶面原子的配位键，不饱和键以及电荷的种类和分布，研究空气中分子氧在In2O3不同暴露晶面上的吸附及其与测试气体的反应，揭示高活性晶面气敏性能增强的根本原因。为高性能气体传感材料的开发提供理论和技术上的支持。

金属氧化物基气敏传感材料是材料科学研究的重要方向之一。本项目主要采用水热溶剂热法，利用结构引导剂制备气敏性质增强的暴露高活性晶面的六方相In2O3,同时研究高活性晶面气敏性质增强的物理机制。研究了通过高温煅烧暴露{020}晶面InOOH六角星纳米结构所得六方相In2O3{-667}高指数晶面的原子排布结构，确定{-667}高指数晶面是由五级(-111)晶面台阶和一个(-112)晶面组成。详细研究了高温下单晶正交相InOOH六角星纳米结构向单晶六方相In2O3六角星纳米结构转化过程中， 二者不同晶带轴方向对应晶面之间的转变情况，提出了形成六方相In2O3{-667}高指数晶面的可能机理。测试了暴露{-667}高指数晶面的单晶六方相In2O3六角星纳米结构传感器对不同浓度的乙醇蒸汽和氢气的气敏性能，发现六方相In2O3的{-667}晶面具有增强的气敏性质。通过InCl3水溶液、NaAc、NaF和EG在200 oC下水热反应24 h，制备了上下顶点之间的距离约为 1.3-2.0 μm，中截面平均边长约为0.7-1.0 µm的正交相InOOH六棱双锥结构。研究确定了所制备InOOH六棱双锥结构暴露的表面分别是正交相InOOH的±(220), ±( -220), ±(121), ±( -12-1 ), ±( -121) 和±(12-1 )晶面。所得InOOH六棱双锥结构晶高温煅烧得到六方相In2O3六棱双锥结构。研究了其对丙酮、乙醇、甲醛和三乙胺的气敏传感特性。 发展了氢化提高气体灵敏度的通用方法，依据表面结构变化，提出表面不饱和金属原子为传感反应活性位的传感机制。此外，还进行了暴露高活性晶面II-VI族半导体纳米结构材料的设计制备及其表面增强的光催化性质研究，揭示了其暴露晶面和增强的光催化特性之间的联系，为高效偶氮染料光降解催化剂的制备提供了理论基础。