铁酸盐系高能/界面钝化的纳米异相异质结材料的可控合成及去除NOx的机理研究

As the most important precursors of the secondary organic aerosols (SOAs), nitrogen oxide (NOx) are the primary gaseous pollutants in the atmosphere that cause the frequent occurrence of regional heavy haze events. Hence, controlling the concentration of NOx in the atmosphere by developing the nano-photocatalysts with the broad spectrum, green, highly efficient visible light response, is of great significance to improve the air quality of our country. This project intends to controllably synthesize multifarious novel ferrite-based cubic/orthorhombic-AFeO3（A=La, Bi, Ga, Y, Pr, Al）nano out-phase heterojunctions under the prediction and guidance of density functional theory (DFT) calculations, and enhance the performance of visible light absorption, carriers separation, interface passivation, NOx adsorption and removal of the synthesized heterojunctions, with the aim to achieve the highly efficent adsorption and removal of NOx in the atmosphere. Through the combination of insitu fourier transform infrared spectroscopy (FTIR) analysis and DFT calculations, it will be explored that the influence mechanism of surface/interface properties, active adsorption sites, charge carriers transfer and transformation, reactive oxygen species, and main environmental factors of the out-phase heterojunctions on NOx removal; The photocatalytic reaction path of NOx removal in the atmosphere will be established. This project will elaborate the intrinsic relationship among the composition, structure, surface/interface properties and NOx removal performance of cubic/orthorhombic-AFeO3 nano out-phase heterojunctions, and provide an innovative technique of high efficiency and deep treatment for regional NOx reduction.

氮氧化物（NOx）是大气中二次气溶胶的重要前体物，是导致区域灰霾现象的重要气态污染物，开发广谱、环境友好、高效可见光响应的纳米光催化材料控制大气中NOx浓度水平，对改善我国空气质量具有重要意义。本项目拟通过密度泛函理论（DFT）计算预测并改进自牺牲原位合成工艺制备具有特定形貌的铁酸盐系cubic/orthorhombic-AFeO3（A=La, Bi, Ga, Y, Pr, Al）纳米异相异质结，增强其可见光吸收、载流子分离、界面钝化、NOx吸附及反应等性能，实现对大气中NOx的强效吸附和去除。采用原位红外分析与DFT计算结合的手段，揭示异相异质结表/界面性质、活性吸附点位、载流子迁移转化、活性氧物种及关键环境因素对NOx去除的增强机制，构建其光催化去除大气中NOx的反应途径，阐述其组成-结构-表/界面性质-NOx催化性能之间的关联，为区域NOx污染减量提供一种高效深度处理的创新技术。

“十三五”以来，我国臭氧（O3）污染浓度呈现逐年加重的趋势。O3的非线性形成机制导致了其关键前体物氮氧化合物（NOx）和挥发性有机化合物（VOCs）的控制难度极大。通过构筑异相异质相、金属负载、空位诱导的强关联界面，调控与强化热电子和载流子迁移特性，多电子活化表/界面甲醛（HCHO，典型VOCs）和NOx吸附位点，诱导C-H键解离促成高反应活性基团，降低反应活化能垒，有效地调控反应氧物种以及产物等；国际上首次提出了氧化锆异相结界面甲醛的非均相常温催化的D-H+Mvk新机制，揭示了异相结构、反应界面调控以及H2O2在光催化NOx的自由基反应中的关键作用，在常温条件实现了下对环境低浓度HCHO和NOx的高效去除（分别为81%和50%），并建立了一套原位傅里叶变换红外光谱仪（insitu-FTIR）与密度泛函理论（DFT）计算联用的O3气态前体物非均相反应路径解析方法；此外，开展了建筑物外立面光催化玻璃幕墙的应用基础研究工作。以上研究工作丰富了传统的光/常温催化机制，为高效光/常温催化材料设计和局域大气污染控制提供了科学理论的支撑和新的策略。