Platform molecular materials and surfaces for solar fuels generation

拟议的研究计划旨在了解系统如何利用阳光产生电荷来驱动太阳能燃料产生的催化剂。这一目标是通过建立对太阳能转换动力学基本现象的理解和表征，通过工程和合成具有目标功能的纳米和中尺度结构，以及通过将太阳能转换现象跨时间和空间结合起来来实现的。更具体地说，本提案旨在回答以下核心问题：分子材料的结构如何决定光捕获和电荷传输的效率，以及如何修改材料特性以利用从纳米尺度到中尺度可扩展的系统的分层组装？******太阳能燃料催化依赖于发色团/催化剂和/或底物之间的单电子转移事件。为了驱动光子吸收后发生的双分子反应中的催化作用，必须在所有组分中执行仔细的氧化还原调平。在这项工作的第一个主要焦点是设计、制备和表征太阳能燃料催化剂的分层方法。虽然在均相系统中进行机理研究通常更容易，但多相催化剂的稳定性和可回收性的提高使其受益。两种方法的结合涉及分子发色团和已知催化剂在非均相半导体表面上的吸附。结合分子催化剂、染料和半导体表面的光电化学（PEC）电池很少存在，因为必须优化一系列变量才能使功能良好的染料敏化光电化学装置（DS-PEC）。******在本提案的第二个主要重点中，串联DS-PEC装置将采用自下而上的方法开发。半导体将在表面生长，随后通过吸附无机超分子发色团-催化剂组件实现功能化。在光照射下的电化学测量将确认在发色团附近存在的催化剂的还原或氧化，而在密封的电化学电池中存在催化量的水或酸的长时间照射将产生可测量量的所需气体（O2和H2）。******这项工作的长期愿景是发展基础知识，结合材料和方法，设计出更有效的太阳能燃料生产技术（例如将二氧化碳转化为增值产品，或将质子还原为氢）。最终，这一战略提供了以卓越性能运行的能源转换系统的工程，同时指导技术上卓越的劳动力，能够解决与能源相关的问题。

The proposed research program seeks to understand how systems can use sunlight to generate charges to drive catalysts for solar fuels generation. This goal is realized through building an understanding of and characterizing the basic phenomena of solar energy conversion dynamics, by engineering and synthesizing nano- and mesoscale architectures with targeted functionality, and by combining solar energy conversion phenomena across time and space. More specifically, this proposal seeks to answer the following central questions: how does the structure of molecular materials determine the efficiency of light capture and charge transport, and how can material properties be modified to take advantage of hierarchical assembly for systems scalable from the nano- to the mesoscale? ******Solar fuels catalysis relies on single electron transfer events between a chromophore/catalyst and/or a substrate. To drive catalysis in bimolecular reactions that occur after photon absorption, careful redox leveling must be implemented across all components. In the first major focus of this work a hierarchical approach to designing, preparing, and characterizing solar fuels catalysts will be undertaken. While mechanistic investigations are often easier to carry out in homogeneous systems, heterogeneous catalysts benefit from increased stability and recyclability. A combination of both approaches involves the adsorption of molecular chromophores and known catalysts onto heterogeneous semiconductor surfaces. Few photoelectrochemical (PEC) cells that combine molecular catalysts, dyes and semiconductor surfaces exist, due to the array of variables that must be optimized to make a functioning dye sensitized photoelectrochemical device (DS-PEC).******In the second major focus of this proposal, tandem DS-PEC devices will be developed utilizing a bottom-up approach. Semiconductors will be grown on surfaces and subsequently functionalized by adsorbing inorganic supramolecular chromophore-catalyst assemblies. Electrochemical measurements in the presence of light irradiation will confirm reduction or oxidation of catalysts present in proximity to the chromophores, while prolonged irradiation in the presence of catalytic amounts of either water or acid in a sealed electrochemical cell will yield measurable amounts of desired gasses (O2 and H2).******The long-term vision of this work is to develop fundamental understanding coupled with materials and methods to engineer dramatically more efficient technologies for solar fuels production (e.g. conversion of CO2 to value added products, or the reduction of protons to hydrogen). Ultimately, this strategy affords the engineering of energy conversion systems operating with exceptional performance while mentoring a technically exceptional workforce capable of solving energy-related problems far into the future.