二甲基硫醚类传感器金基栅电极材料的修饰与性质理论研究

The in-situ detection of the dimethyl sulfide compounds is essential to the 48-hour forecast of the black water bloom, which is the ecological disaster occurring in the eutrophic lakes. However, the instability of the compounds on the metal surface of the gate electrode restricts the developing in-situ sensors. Therefore finding a suitable gate electrode material is highly desired. Considering simulations of chemical reactions at liquid-electrode interface are the frontier and hot issue of theoretical surface science, we, in this proposal, will investigate the adsorption and decomposition mechanisms of the dimethyl sulfides on the decorated surfaces of the gold-based gate electrode and the effect of the decoration, aqueous phase and electric field on the mechanisms. The quantitative relationship between the work function of the decorated gold-based gate electrode and the coverage of the adsorbates will be explored, and the response law of the gate electrode to the different types of dimethyl sulfide molecules will be revealed. In addition, the features of electronic structures of eligible electrode material and the characters and optimal content of the doping element will be identified and elucidated. Not only will the results of this project provide valuable and informative theoretical guidance for developing the gate electrode material of the in-situ sensor for detection of the dimethyl sulfide compounds, but also further enrich the simulation theory and methods to be applied in the liquid-electrode surface study.

二甲基硫醚类化合物的原位检测对于富营养化湖泊"湖泛"生态灾害暴发的48小时预警至关重要。然而该类化合物在金电极表面稳定性差，制约了原位传感器的实际应用。因此亟需研制适合的栅电极材料。本项目着眼于液相电极界面上的化学反应理论研究这一表界面理论模拟的前沿和热点问题，通过理论化学方法研究二甲基硫醚类分子在修饰的金基栅电极表面的吸附与解离机理以及修饰方式、水介质环境和电极电场等因素对上述吸附和解离的影响，探索被修饰的金基栅电极表面功函数与吸附质覆盖度之间的定量关系，揭示栅电极对不同二甲基硫醚类分子的响应规律，阐明适宜栅电极材料的电子结构特征、修饰原子、修饰浓度等因素。本项目的研究结果不但可为设计研制二甲基硫醚类化合物原位传感器的栅电极材料提供有价值的理论指导，而且也必将进一步丰富液相电极界面模拟的理论和研究方法。

本项目建立了一种计算不同配位环境的格点原子间相互作用的通用理论方法，并对金原子成功发展出了两套非经验能量参数。本项目发展了线性活化能关系，提出了不依赖经验参数、满足微观可逆原理的金属表面过程活化能计算方法。利用项目建立与发展的方法，我们对Au(111)表面的单原子扩散进行了动力学蒙特卡罗研究，获得了与实验、理论相符的研究结果，确定了Au表面自扩散系数与势垒，进一步验证了本项目方法的可靠性。在此基础上，本项目还对包含较多原子的金纳米颗粒形貌进行了研究，分别考察了自由金纳米颗粒与底物表面的金纳米颗粒。研究了前者的相变过程以及表面性质对后者的作用，发现了栅基性质与表面金属颗粒形貌之间的关系，揭示了金属纳米颗粒的活性位点。项目以理论化学为手段，通过考察DMS与DMSD在栅电极金表面的吸附，研究了二甲基硫醚类金属栅电极传感器的可行性；通过增加溶剂化效应与外电场，研究了栅电极对模拟环境的响应；通过表面修饰，探索了金属栅电极传感器的稳定性。本项目研究不仅建立了新的理论模型与方法，还从理论上探讨了金属栅电极二甲基硫化物传感器的可行性，从而进一步推动了湖泛监测预警技术的理论发展，符合社会对环境保护的需求。