光生电荷和表面氧空位协同增强氧化锌室温高灵敏快速NO2传感

The detection of NO2 plays a key role in air pollution control. Presently, the NO2 gas sensors based on metal oxide ceramics should operate at high temperatures, since they generally suffer from low sensitivity and slow response/recovery at room temperature. This project proposed a novel approach for high-sensitive, rapid sensing of NO2 at room temperature, by taking advantage of the synergistic effects of photogenerated charges and surface oxygen vacancies in ZnO: on one hand, the surface oxygen vacancies would improve the separation efficiency of photogenerated charges, thus enhancing the NO2 adsorption/desorption and electron transfer induced by photogenerated charges; on the other hand, the photogenerated charges would strengthen the "electron donor" function of surface oxygen vacancies in the NO2 adsorption and electron transfer processes. The design and fabrication of ZnO sensitive materials with rich surface oxygen vacancies, high surface area and hierarchical structures will be developed. The synergistic effects of photogenerated charges and surface oxygen vacancies on the room-temperature NO2 sensing property of ZnO will be studied under visible-light illumination, to establish the relationship between charge separation efficiency and NO2 sensing property. Furthermore, the evolution of surface oxygen vacancies and NO2 adsorption/reaction processes will be investigated using multiple in-situ techques, to reveal the "electron donor" function of surface oxygen vacancies enhanced by photogenerated charges and their roles in NO2 sensing. This work is expected to pave a facile pathway to the fabrication of high-performance room-temperature NO2 sensors with low energy consumption, high safety and wide applicability.

NO2监测是大气污染防治的关键环节。基于金属氧化物陶瓷的NO2传感器大多需高温工作，室温下存在灵敏度低、响应/恢复速率慢的问题。本项目提出光生电荷和表面氧空位协同增强氧化锌室温高灵敏、快速NO2传感的思路：利用表面氧空位提升光生电荷分离效率，增强光生电荷对NO2吸附、脱附和电子转移的促进作用；同时光生电荷可强化表面氧空位在NO2吸附和电子转移中的“电子供体”功能。拟发展具有表面富氧空位、高比表面多级结构特征的氧化锌敏感材料设计与可控制备；研究可见光激发下，光生电荷和表面氧空位对氧化锌室温NO2传感的协同增强作用，查明表面氧空位调控的光生电荷分离效率对NO2传感性能的影响规律；利用多种原位表征分析传感过程表面氧空位状态变化和NO2吸附、反应历程，揭示光生电荷对表面氧空位“电子供体”功能的强化作用及其进一步增强NO2传感的机理。研究有望为低能耗、安全、适用性强的室温NO2传感技术探索新途径。

NO2监测是大气污染防治的关键环节。基于金属氧化物陶瓷的NO2传感器大多需高温工作，室温下存在灵敏度低、响应/恢复速率慢的问题。本项目提出光生电荷和表面氧空位协同增强氧化锌室温高灵敏、快速NO2传感的思路。基于"高过饱和度诱导快速结晶"途径，成功制备了若干种具有表面富氧空位、高比表面多孔特征的ZnO多级结构气敏材料，系统研究了这些气敏材料在光激发下的室温NO2传感性能，揭示了光生电荷和表面氧空位对氧化锌室温NO2传感性能的协同增强作用规律。程序升温氧脱附分析、原位电子顺磁共振谱、原位红外光谱等多种分析表明，表面氧空位在O2、NO2气体吸附中充当活性位点，在光激发下可捕获光生电子而强化其“电子供体”功能，即表面氧空位和光生电荷协同促进活性氧形成、NO2 室温吸附和电荷转移过程，从而提升NO2传感性能。本项目还通过在富氧空位ZnO表面修饰其它光敏材料（如光敏聚合物、贵金属纳米颗粒等），利用电荷转移效应提高其在光激发下的光生电荷浓度，进一步增强室温NO2传感性能。此外，本项目还将光生电荷和表面缺陷协同增敏策略拓宽至其它气敏材料体系（如其它金属氧化物、过渡金属硫化物等）及其它气体（如甲醛、甲烷等）的室温检测中。本项目研究成果不仅发展了基于氧化锌气敏材料的室温高灵敏快速NO2传感技术，建立的光生电荷和表面缺陷协同增敏策略还具有普适性，可为室温型气体传感器的开发和性能增强提供通用思路。