半金属铋单质直接等离子体光催化作用与“记忆效应”机制探索

The applicants have discovered the phenomena of plasmon-mediated direct photocatalysis and “memory” capability of semimetal Bi element. In order to solve the key scientific problems based on this discovery, this proposal is expected to realize the size and morphology control of Bi element through optimizing the synthesis conditions systematically. The localized surface plasmon resonance (SPR) of Bi element can be observed by electron energy-loss spectroscopy (EELS). Mie theory (MT) and a finite integration technique (FIT) for Maxwell equation were used to simulate the SPR absorption spectra and simulate the electromagnetic field distribution of Bi element arising from SPR for elucidating the influence of size and morphology of Bi element on the SPR effets. The mechanism of direct plasmonic photocatalysis of Bi element will be revealed by analyzing the production, transfer and life-time of photo-induced charge carriers and active radical species using the time resolved fluorescent spectra and electron spin resonance. The proposal will also analyze the active species and their variation during the light irradiation and after turning off the illumination to reveal the origin of the “catalytic memory” capability. The as-synthesized Bi element will be applied in purification of NO at ppb level and the relationship between materials microstructure and plasmonic photocatalytic activity will be established. By considering the variations of active species and the analysis of the concentration and distribution of intermediates and final products as well as the active species variation, the reaction mechanism for direct plasmonic photocatalytic removal of NO by Bi element will be revealed, which could provide technological basis for the future applications. This research is expected to shed new light on the understanding of plasmonic photocatalysis mediated by non-noble metals.

申请者在探索中发现了半金属铋单质直接等离子体光催化和“记忆效应”现象。本项目在此基础上针对若干关键科学问题，通过系统优化铋单质合成工艺条件，实现对其形貌和尺寸的控制；通过电子能量损失谱观察铋单质的等离子体效应，用米氏理论和麦克斯韦方程数值计算方法模拟铋单质的等离子体吸收光谱和等离子体电磁场分布，揭示铋单质形貌和尺寸对其等离子体效应的影响规律；采用时间分辨荧光和电子自旋共振谱等研究铋单质在光照下载流子的生成迁移、寿命和活性自由基物种，阐明铋单质直接等离子体光催化作用机制；分析铋单质光照前后活性物种及其变化规律，明晰铋单质具有记忆效应的起因。将铋单质应用于低浓度NO净化，建立其微结构与光催化性能之间的构效关系。分析光催化过程中间产物和终产物的浓度和分布，结合活性物种变化规律，揭示铋单质等离子体光催化去除NO的反应机理，为其走向应用奠定基础。本研究可为深入认识非贵金属等离子体光催化提供崭新思路。

非贵金属Bi单质的等离子体光催化现象被发现后引起了国内外的广泛的关注，但是Bi单质的直接等离子体光催化作用机制和作为助催化剂提升其他光催化剂的机制还未被阐释清楚。项目组通过系统优化铋单质合成工艺条件，实现对其形貌和尺寸的控制；通过电子能量损失谱观察铋单质的等离子体效应，用米氏理论和麦克斯韦方程数值计算方法模拟铋单质的等离子体吸收光谱和等离子体电磁场分布，揭示铋单质形貌和尺寸对其等离子体效应的影响规律；采用时间分辨荧光和电子自旋共振谱等研究铋单质在光照下载流子的生成迁移、寿命和活性自由基物种，阐明铋单质直接等离子体光催化作用机制；分析铋单质光照前后活性物种及其变化规律，明晰铋单质具有记忆效应的起因。将铋单质应用于低浓度NO净化，建立其微结构与光催化性能之间的构效关系。分析光催化过程中间产物和终产物的浓度和分布，结合活性物种变化规律，揭示铋单质等离子体光催化去除NO的反应机理，为其走向应用奠定基础，为深入认识非贵金属等离子体光催化提供崭新思路。.采用化学溶液沉淀法、溶剂热法和原位还原法制备了具有等离子效应的Bi单质纳米颗粒和实心微球，实现了纳米颗粒在8-80 nm范围内的精确调控。将Bi单质作为助催化剂应用于复合光催化剂体系，设计合成了Bi颗粒与六边形晶体BiPO4、Bi/Bi3O4Cl纳米带、Bi/Bi4MoO9核壳结构、Bi/Bi2O3修饰的无定形Bi2WO6、Bi纳米颗粒/SiO2、单分散Bi颗粒/g-C3N4、Bi微球/氧化石墨烯、Bi/(BiO)2CO3和Bi/无定型氧化铋等Bi单质基复合光催化剂。将制备的光催化剂应用于空气中NOx的去除，表现出优异的光催化性能，原因是Bi单质的等离子体效应可促进电荷分离和光吸收效率的提升。本项目证实了用Bi单质替代贵金属助催化剂的可行性，在环境净化应用展现了良好的前景。.项目负责人发表和录用标注项目编号的SCI论文36篇（含ESI高引论文7篇）。以第一或通讯作者在Applied Catalysis B: Environmental, Catalysis Science & Technology, Chemical Communications, Chinese Journal of Catalysis等发表和录用SCI论文11篇。