SusChEM: Understanding and controlling photoinduced self-exchange reactions across sensitized mesoporous thin films to drive multiple-electron-transfer catalysis

加州大学欧文分校的Shane Ardo教授在化学系化学催化项目的支持下研究染料敏化太阳能电池（DSSCs）。DSSCs是一种廉价的商业太阳能电池替代品，但表现出较低的太阳能转换效率，阻碍了其商业化。该项目正在研究一种替代反应，以显着提高含碘DSSCs的效率，从目前的世界纪录约12%提高到20%以上。该项目促进了科学进步，促进了环境管理。该研究项目还举办了外联讲习班，目的是提高女中学生对太阳能转换研究的参与和兴趣。该研究的动机是DSSCs和染料敏化太阳能燃料功能组件的一种新的运行机制，其中多电子转移氧化还原穿梭化学是在共锚定在染料敏化纳米晶TiO2上的分子电催化剂上驱动的。基础研究包括(i)多电子转移氧化还原穿梭氧化的表面约束电催化，（ii）固定在TiO2表面的分子之间的自交换电子转移，以及（iii）氧化的表面固定分子在TiO2中的电子（缓慢）重组。合成了一系列聚合物材料和铂、钯有机金属配位化合物，并研究了它们促进球内碘化物氧化电催化的能力。染料的分子结构是多样的，以识别那些具有最快的自交换电子转移和最慢的重组。同时研究了二氧化钛结合的电催化剂和染料，以探究几种相互作用功能的影响，并以实现高效的光驱动碘化物电催化为目标。电催化工作使用旋转环盘电极装置和/或循环伏安法来评估分子的催化能力。染料现象被询问使用光谱电化学和纳秒泵探针瞬态吸收和时间分辨光致发光（偏振）光谱。除了光谱建模瞬态光谱和极化动力学，数值模型和蒙特卡罗模拟有助于澄清是什么控制（期望的）自交换电子转移和（不希望的）重组的速率。

Professor Shane Ardo of the University of California-Irvine is supported by the Chemical Catalysis program in the Division of Chemistry to investigate dye-sensitized solar cells (DSSCs). DSSCs are an inexpensive alternative to commercial solar cells but have exhibited low solar-energy-conversion efficiencies that hamper their commercialization. This project is investigating an alternative reaction to dramatically increase the efficiency of iodide-containing DSSCs, from their current world-record efficiency of ~12% to over 20%. The project promotes the progress of science and facilitates environmental stewardship. Outreach workshops accompany this research program with the aim of increasing the participation and interest of female middle-school students in research related to solar energy conversion.The research is motivated by a new mechanism of operation for DSSCs and dye-sensitized functional assemblies for solar fuels where multiple-electron-transfer redox-shuttle chemistry is driven at molecular electrocatalysts co-anchored to dye-sensitized nanocrystalline TiO2. Fundamental studies include (i) surface-confined electrocatalysis of multiple-electron-transfer redox-shuttle oxidation, (ii) self-exchange electron transfer between molecules anchored to the TiO2 surface, and (iii) (slow) recombination of electrons in TiO2 with oxidized surface-anchored molecules. Several series of polymeric materials and Pt and Pd organometallic coordination compounds are synthesized and investigated for their ability to facilitate inner-sphere iodide oxidation electrocatalysis. The molecular structure of dyes is varied to identify those with the most rapid self-exchange electron transfer and slowest recombination. TiO2-bound electrocatalysts and dyes are studied simultaneously in order to interrogate the effects of several interacting functions and with the aim of realizing efficient light-driven iodide electrocatalysis. The electrocatalysis work is performed using a rotating ring-disk electrode setup and/or cyclic voltammetry to assess the catalytic competency of the molecules. Dye phenomena are interrogated using spectroelectrochemistry and nanosecond pump-probe transient-absorption and time-resolved photoluminescence (polarization) spectroscopies. In addition to spectrally modeling transient spectra and polarization kinetics, numerical models and Monte Carlo simulations helps clarify what controls the rate of (desired) self-exchange electron transfer and (undesired) recombination.