薄膜晶体管光电催化COD传感器的栅极结构调控及其敏感机理研究

Research and development of highly sensitive, integratable and online real-time monitoring methods and sensors for chemical oxygen demand (COD) determination are crucial for the reliable monitoring applications in water environment. The photoelectrocatalytic COD sensors based on the thin-film transistors are proposed in the project using the photocatalytic metal-oxide semiconductors as the gate electrode. The sensors combine the advantages of both the typical photoelectrocatalytic COD sensors and the thin-film transistors. The rational design and modification of the gate electrodes, including changing the materials composition, microstructure, surface/interface nature and energy-level alignment, are of great significance to improve the COD detection properties. These thus require a systematic study on the relationship among the materials preparation, structure modification, surface decoration and the corresponding photoelectrocatalytic COD determination. The influence of COD photoelectrocatalysis at the gate surface on the sensing properties will be further investigated. The relationship between the capacitance at the gate/electrolyte interface and the response current in the channel will also be explored to clarify the underlying sensing mechanism, which is beneficial to improve the response and recovery performance and to broaden the detection range of the COD sensors. The purpose of the project is to achieve a real-time online COD determination method with high sensitivity, high selectivity and fast response using the photoelectrocatalytic sensors based on the thin-film transistors.

研究开发满足未来高灵敏度、集成化、实时在线监测需求的水质化学需氧量（COD）检测方法及传感器是水环境监测领域研究的重要课题。本项目将典型的光电催化技术和新型的薄膜晶体管器件有机结合，选择具有光催化活性的金属氧化物半导体作为栅极构建基于薄膜晶体管的光电催化COD传感器。从栅极的结构调控入手，改变栅极材料组成结构、微观几何结构、表面/界面结构和能级结构，研究栅极/电解液界面结构与电极电容的关系，探明界面电容对界面电势分布的影响规律以及对沟道电流响应信号的调控机理，找到通过栅极界面结构优化提高传感器性能的方法。深入研究栅极光催化反应对传感器性能的影响机制，通过栅极光催化材料的精细设计达到对光电催化COD传感器检测性能的可控调制，改善传感器的响应恢复性能和拓宽检测范围，实现对水体COD值高灵敏度、高选择性、快速响应的实时在线检测，并且为薄膜晶体管光电催化传感器的推广应用奠定科学与技术基础。

化学需氧量（Chemical Oxygen Demand，COD）是环境监测中用于评价水体受有机物污染程度的一项重要指标，是水质综合评价的重要参数之一。及时准确地监控水体COD 值，对水污染防治具有极其重要的意义。研究开发满足未来高灵敏度、集成化、实时在线监测需求的水质COD检测方法及传感器是水环境监测领域研究的重要课题。.本项目有机结合了传统光电化学COD传感器和薄膜晶体管的结构特点，利用具有光催化活性的金属氧化物半导体作为薄膜晶体管的栅极，通过栅极光催化降解水体有机物测定COD值。使用阳极氧化法等工艺，在栅极表面构筑TiO2纳米阵列结构，进一步通过在表面沉积Au、Pt等贵金属纳米颗粒或者复合不同能带宽度的半导体材料构建异质结构，提高栅极材料的光催化活性以及改善传感器的选择性。实验中开发了基于有机薄膜晶体管的光电催化传感器，对水质COD的检测限比传统光电化学法低两个数量级，达到 0.01 mg/L；进一步成功开发出基于硅场效应晶体管的延伸栅极COD传感器，在流速为1.0 mL/s时，该传感器的检测限低至0.12 mg/L，线性范围从1.44 mg/L到672 mg/L。系统的测试表征结合对实际水样的分析表明，研发的传感器具有良好的选择性、稳定性和可靠性。该传感器结构既保持了光电催化法检测速度快、灵敏度高、无二次污染等特点，又发挥了薄膜晶体管特有的信号放大功能，使其具有灵敏度高、微型化、集成化等特点，非常适用于对水质变化的实时在线跟踪及其变化早期的动态监测。.截止到2022年1月，在Sensors and Actuators B: Chemical等重要学术刊物上发表了18篇高水平论文，培养掌握薄膜晶体管和传感器技术的8名研究生，申请国家发明专利5项（已经获批2项）。受邀在国内外学术会议上作学术报告9次。