卟啉分子修饰石墨烯的NOx传感性能的研究

The sensing materials play an important role in the performances of NOx gas sensors. Currently, much attention has been paid on preparation of NOx sensors based on semiconductor materials, which exhibit some onvious disadvantages, including high operating temperature and relatively high detection limit. Graphene has shown many unique properties, such as high specific surface area, high carrier mobility, excellent mechanical property, stable physical and chemical property and room temperature electrical conductivity, which can make up for the shortcomings of the semiconductor sensing materials. However, the low sensitivity, slow response and recovery and poor selectivity have to be the bottleneck in the development of NOx sensors based on pure graphene. The applicant puts forward preparation of novel NOx sensors based on graphene modified with porphyrins. With the aid of the conjugated π bond structures and numerous functional groups, porphyrins can regulate electron transport capacity, the type and quantity of surface active sites in graphene, leading to improving the identification capacity and adsorption capacity of graphene-based materials toward NOx molecules. The goal of the present project is development of graphene-based NOx sensors with good sensing performances in terms of operating at room temperature, high sensitivity, rapid response and recovery, as well as high selectivity. The project will combine the needs of the NOx sensors, design a serial of graphene modified with porphyrins materials, examine sensing characteristics of such graphene materials, reveal the relationship between micro-environment in sensitive groups and the gas sensing performances, investigate the sensing mechanism of graphene modified with porphyrins for NOx sensing, and sum up the electron transfer mechanism among graphene, porphyrins and NOx molecules, providing the scientific basis for high-performance NOx gas sensors having practical value.

传感材料是决定NOx气体传感器传感性能的关键，目前广泛研究的半导体型NOx传感器具有工作温度高、检测限不够低等缺点。石墨烯具有大的比表面积、高的载流子迁移率、良好的机械性能、稳定的物理化学性质以及室温导电性，这些特点恰好可以弥补半导体气敏材料的缺点，但是，灵敏度低、响应恢复慢以及选择性差等问题是纯态石墨烯型NOx传感器发展的瓶颈。申请人提出开发基于卟啉分子修饰石墨烯的NOx传感器，利用卟啉分子的共轭π键结构和丰富的官能团，调控石墨烯的电子传输能力,改善石墨烯表面活性位点的种类与数量，提高石墨烯对NOx分子的识别能力和吸附能力，目标是获得可室温工作、灵敏度高、响应恢复迅速、选择性高的NOx传感材料。研究石墨烯材料的气敏特性，揭示敏感基团的微环境与气敏性质之间的关系，探讨石墨烯材料的传感机制，总结电子在石墨烯、卟啉以及NOx之间的传输机制，为实现具有实用价值高性能的NOx传感器提供科学依据。

石墨烯基气体传感器的优点是可以实现室温检测气体，其面临的主要瓶颈问题是灵敏度低、响应恢复速率慢等问题。本项目以作为气体传感器核心的气体敏感材料为研究目标，通过调控石墨烯基敏感材料结构特征的方法，提高石墨烯基气体传感器的传感性能。提出金属氧化物表面修饰石墨烯的新方法，利用石墨烯与金属氧化物的协同作用，提高石墨烯基气体传感器的灵敏度及响应恢复速率；采用引入贵金属纳米粒子、组装碳纳米管等方法，进一步提高石墨烯基气体传感器的传感性能。通过本项目的实施，获得了一系列高性能石墨烯基敏感材料的制备新方法，开发了一系列表面修饰石墨烯基气敏材料的新技术，构建了多种基于金属氧化物纳米粒子修饰石墨烯材料的室温气体传感器。获得了一系列具有不同结构和稳定物理化学性质的石墨烯基气敏材料，制备了一批具有优良气敏特性的气敏元件，系统研究了不同类型石墨烯基气敏元件的传感特性、敏感材料结构与气敏性能之间的关系以及传感机理等，并整理、发表了一系列学术论文。本项目的实施为实现具有实用价值的石墨烯基室温气体传感器的开发提供科学依据。