SusChEM: Studying Catalysts and Reaction Intermediates for Water Oxidation by Spectroscopy of Cryogenic Mass-Selected Ions

获得化学结构、动力学和机制A项目的奖项后，科罗拉多大学博尔德分校的马蒂亚斯·韦伯开发了一种新的实验方法来研究太阳能转换反应堆中发生的化学反应。正在研究的反应器类型利用含有钌或铜的催化剂分子将水分子分解为氢和氧。因此，来自阳光的能量被用来从水中提取可持续的燃料来源，但其工作的确切方式尚不完全清楚。这种认识的缺乏阻碍了这一重要工艺过程的催化剂和反应器的设计和改进。研究这一系统的一个复杂因素是水本身的存在。目前的研究是通过去除太阳能反应堆中产生的分子并将其放入真空中来解决这个问题。然后可以使用高度复杂的设备来研究这些化学物质的详细性质。然后，在真空中进行的测量将提供可用于在有水存在时识别这些物种的特征，换句话说，在正常运行的反应堆中。这项工作解决了一个重要的社会问题，即开发不依赖碳基燃料的替代能源。培养下一代科学家是这个项目的一个组成部分。通过周六上午的科学项目，包括5到9年级的崭露头角的研究人员。在这个项目中，研究人员正在研究选定的钌基和铜基水氧化催化剂的电子和几何结构，以及催化转化过程中产生的某些反应中间体。催化剂和反应中间体的离子通过电喷雾电离转移到气相。然后，离子在离子阱中冷却，选择质量，并通过脉冲光照射，该脉冲光可在整个中红外，可见光和近紫外光谱中进行调节。光子吸收是通过目标离子的光破碎来监测的，允许测量它们的振动和电子光谱。将离子冷却到低温是获得必要的光谱细节的关键。振动光谱将得到所研究离子的结构信息，这对反应中间体尤其重要。测量催化剂和反应中间体的电子能谱将有助于澄清反应溶液中的形态。此外，激发态振动结构有助于研究人员进行激发态动力学和反应性的计算建模研究。

With this award from the Chemical Structure, Dynamics and Mechanisms A program, Mathias Weber of the University of Colorado at Boulder develops a new experimental approach to study chemical reactions that occur in a solar energy conversion reactor. The type of reactor being studied utilizes a catalyst molecule that contains either ruthenium or copper to split water molecules into hydrogen and oxygen. Energy from sunlight is, thus, used to extract a sustainable source of fuel from water, but the precise way it works is not fully understood. This lack of understanding hinders the design and improvement of catalysts and reactors for this important technological process. One of the complicating factors in studies of this system is the presence of the water itself. The current research is getting around this problem by removing the molecules produced in the solar reactor and putting them into a vacuum. Highly sophisticated pieces of equipment can then be used to study the detailed nature of these chemical species. The measurements made in vacuum will then provide signatures that can be used later to identify those species when water is present, in other words, in the reactor as it normally functions. The work addresses an important societal problem, the development of alternative sources of energy that do not rely on carbon-based fuels. Training the next generation of scientists is an integral part of this project. It includes budding researchers as young as grades five through nine through a Saturday morning science program.In this project, the investigators are studying the electronic and geometric structures of selected ruthenium- and copper-based catalysts for water oxidation, as well as certain reaction intermediates that arise in the catalytic conversion process. Ions of catalyst and reaction intermediates are transferred into the gas phase by electrospray ionization. The ions are then cooled in an ion trap, mass selected, and irradiated by pulsed light, which is tunable throughout the mid-IR, visible and near-UV spectrum. Photon absorption is monitored by photofragmentation of the target ions, allowing the measurement of their vibrational and electronic spectra. Cooling the ions to low temperatures is crucial to obtain the necessary spectroscopic detail. Vibrational spectra will result in structural information about the ions under study, which is particularly important for reaction intermediates. Measuring the electronic spectra of catalysts and reaction intermediates will aid clarification of speciation in reactive solutions. In addition, the excited state vibrational structure is assisting the investigators in computational modeling studies of the excited state dynamics and reactivity.