钙钛矿组成和分级纳米结构调控混合电位气体传感器性能研究

High performance gas sensors can effectively detect gases released at the early stage of fires, and thus hold great promise for reducing fire hazards and protecting human lives and properties. Currently, the application of mixed-potential type gas sensors is greatly limited due to the fact that key performance does not meet the requirements for practical applications. To guide designing efficient gas sensors, the present proposal plans to explore the tuning mechanism of gas sensor performance, by studying the (electro)catalytic properties of highly active perovskite oxides through controlled regulation of composition and nano-morphology. By measuring the polarization curves and electrochemical impedance spectra, etc., the electrode reaction currents, interfacial impedance, and catalytic conversion will be obtained, which allow quantification of the reaction activities for oxygen reduction, electrochemical oxidation, and heterogeneous oxidation of perovskites. The local structural parameters of the materials, such as oxidation states of cations and oxygen vacancy concentration, will be studied by synchrotron radiation X-ray absorption spectroscopy. In combination with the measurements of gas sensing characteristics, the mechanism how the gas sensor performance is tuned by electrode compositions through the change of materials structure and (electro)catalytic activities will be studied. Furthermore, the relationship between the electrode microstructure and gas sensing performance will be elaborated by studying the variation of electrode reactions with the hierarchical nano-morphologies. Based on these studies, the electrode composition and microstructure will be optimized. The project aims to provide important research basis and useful theoretical guidance for developing high performance mixed-potential gas sensors, which is of vital importance for promoting the scientific research of gas sensors and boosting the technology development for early detection of fires.

高性能气体传感器可有效探测火灾早期释放的特征气体，对于降低火灾危害、保障公众生命财产安全意义重大。现有混合电位型气体传感器在关键性能上难以满足实用要求，其应用受到了严重限制。为指导设计高效传感器，本项目拟基于活性钙钛矿氧化物的组成可调性和纳米形貌变化，以（电）催化性质的系统研究为主线，探讨传感器性能的调控机制。通过极化曲线测试、电化学阻抗谱等方法，测量电极反应电流、界面阻抗和催化转化率，定量表征钙钛矿的氧还原、电化学氧化和多相催化反应活性，并采用同步辐射X射线吸收谱表征金属离子价态和氧空位浓度等局域结构参数，结合气敏特性测试，研究敏感电极组成通过结构和性质调控传感器性能的机制；考察电极反应随分级纳米结构形貌的变化，揭示微结构与传感器性能的相互关系；在以上基础上，优化电极组成和微结构。项目的实施将可为研制符合实用要求的高性能混合电位传感器提供研究基础和理论依据。

气体传感器具有体积小、成本低、可以实时连续监测等优点，在火灾安全、环境监测、工业生产、交通运输、疾病诊断等诸多领域中具有广泛应用的潜力。当前研究的一个焦点和目标在于实现各项关键性能指标均能满足实用要求的传感器的理性设计。混合电位型气体传感器结构简单、稳定性好，但由于影响其性能的关键因素和气敏机理尚不清楚，其发展受到了限制。本项目重点针对这些问题展开了深入研究。通过理论分析推导了混合电位响应在典型场景下的表达式，并对响应的动态过程进行了数值模拟，明确了影响响应大小和响应恢复速度的重要因素，阐释了传感器的气敏机理。基于钙钛矿氧化物的组成可调性和电极纳米形貌控制，定量表征了电极材料的氧还原、电化学氧化和多相催化反应活性，阐释了电化学活性比和电极微结构影响混合电位传感性能的机制。发现混合导电钙钛矿氧化物的反常电位响应特性，利用其显著提高了传统传感器的气敏性能，提出了一种新型的传感机制。另外，还研究了多种基于分级纳米结构半导体氧化物的气体传感器，发展了基于特征气体探测的PVC电缆火灾早期预警技术。项目研究结果可为高性能气体传感器的研制和应用提供重要基础和理论依据。