表面缺陷诱导的光催化NO去除：选择性和表界面机理研究

Nowadays, air pollution has become a globally prominent environmental problem, in which nitrogen oxide (NOx) is one of the most serious pollutants, how to remove low-concentered NO from the air without producing secondary pollution is becoming a challenging research. Environmental nanomaterial based photocatalytic technique has significant roles to play. Based on the density functional theory (DFT) calculation, this project will concentrate on the system of a metal cation Bi3+ with stereo active 6ns2 electrons and highly polarized d0 elements (Ti4+, V5+, W6+ and Mo6+) to design and synthesize visible-light-driven titanium-based perovskites, and further regulate their microstructures (surface defects, morphology, active sites etc.) by varying reaction conditions during a molten salt synthesis for photocatalytic NO removal; The band gap engineering will be achieved by regulating the surface defects (type, distribution, concentration and proportion); The specific reaction pathways, surface adsorptions (interactions) and NO conversion process will be investigated systematically by using in-situ infrared spectroscopy to elucidate the roles of various defects; The effects of microstructures on the photoresponse, electronic structure, band gap composition and NO removal efficiency of the materials will be investigated; Through this project, the methods and profound insights into for inhibiting by-product generation, revealing reaction mechanisms and, improving selectivity of nitrate or nitrogen production as well as quantum efficiency will be provided.

近年来，空气污染成为全球性突出的环境问题，其中氮氧化物 (NOx) 是危害较严重的污染物之一，如何高效去除空气中低浓度的NO，且不产生二次污染，是具有挑战性的课题。以环境纳米材料为核心的光催化在此方面有优势。本项目以密度泛函理论计算为基础，设计含6ns2孤对电子立体活性的金属阳离子Bi3+和具有高度畸化的d0元素 (Ti4+，V5+，W6+和Mo6+) 的可见光驱动的钛基钙钛矿材料，在熔盐合成中通过改变反应条件调节其微观结构 (缺陷、形貌、活性位点)，并用于去除NO；通过控制缺陷 (种类、分布、浓度和比例) 调节其能带结构，结合原位红外光谱跟踪反应过程，阐明NO与催化剂表界面吸附和作用，重点阐明NO转化过程中缺陷的作用，并探索光催化NO去除活性最佳反应条件。通过此项目，为抑制副产物的形成，获得硝酸或氮气等单一转化产物，理解反应机理、提高反应选择性和量子效率提供理论指导。

氮氧化物(NOx)对空气质量的影响日益受到重视，而如何去除或降低其危害依然是目前污染控制领域巨大挑战。光催化转化NO过程可以产生NO2，NO3−或N2，从而降低NO浓度，然而这些产物的形成和反应机制尚不清楚。本项目的研究中，以DFT理论模拟为指导，对钙钛矿类催化剂的晶体结构进行设计，水(溶剂)热合成中实现了催化剂制备和微观结构的调控。通过改变条件获得了Sr2Bi2Nb7O9等5种具有优异微观结构的钙钛矿催化剂并探索了表面微观结构有效调控的方法和机理，同时研究了催化剂对低浓度、高毒性空气污染物NO (ppb)的去除活性。利用原位红外光谱和时间分辨电子自旋共振同步跟踪监测了反应过程，结合DFT计算阐明了NO与催化剂表界面作用，吸附模式；重点阐明了微观结构(缺陷、形貌、晶面和活性位点等)对NO转化产物的形成和反应机制。通过此项目的研究，对微观结构修饰和表界面的调控，NO去除过程中控制单一反应途径的方式抑制副产物的形成，从而提高反应活性和选择性有了深入的理解，为表界面调控及其光催化机理、机制提供了新的研究方法和见解。.通过本资助项目，在ACS Catal.，Appl. Catal. B,等国际刊物上发表论文5篇、会议论文3篇、申请专利7件（含2件授权专利）、参与国内外学术交流9次，参与学术兼职7项、参与学习培训5项，为今后的发展奠定了良好的基础，圆满地完成基金内容，达到预期研究成果。