CAREER: Manipulating energy conversion chemistry with metal overlayer structures

开发用于从二氧化碳和水中生产可再生燃料的改进电催化剂，有可能实现可储存、可运输燃料的长期可持续生产。二氧化碳的来源可能是化石燃料发电厂的排放，也可能是大气本身。虽然实现这一目标的最具成本效益的技术方案仍有待确定，但加速电化学反应的基本方法可以为可持续化学燃料的大规模生产创造一条道路，同时减少二氧化碳的排放。提出的研究目标是了解控制过渡金属表面电化学能量转换过程的因素。具体来说，该研究旨在了解直接反应机制、活性和选择性的因素：1)二氧化碳的电还原生成碳氢化合物和醇等燃料，2)水的电催化生成H2，以及3)氢和醇等燃料的电氧化生成电力的逆反应。在这项工作中获得的基础知识也将有助于提高燃料电池的效率，以及可再生电力用于合成化学燃料的能量存储设备。为了了解控制可再生燃料生产的电催化能量转换过程的因素，金属催化剂的电子和几何结构将被定制，以操纵表面吸附质的键强度。通过这种方法，可以控制关键反应中间体的转化，从而导致电化学转化反应的机理途径、活性和选择性发生重大变化。通过在不同的金属衬底上合成一种特定的金属作为单一的伪晶覆盖层，金属上的化学反应将得到调整。衬底金属的电子结构和晶格常数将影响其上金属单层的关键催化剂性能。电化学测量，结合原位原子尺度成像（扫描探针显微镜）和原位振动光谱（尖端增强拉曼光谱），将获得关于表面反应中间体、机理途径和金属-吸附质键强度的分子水平的见解。实时产品分析耦合电化学电池也将用于进行涉及同位素的动力学研究。更广泛的影响建议的教育活动将与建议的研究相结合。博士生将获得可再生燃料生产的催化和电化学过程的实践专业知识，这是一个新兴领域。一组本科生研究人员也将参与这些活动。该教育计划旨在与斯坦福大学正在进行的项目合作，从代表性不足的工程群体中招募研究生和本科生，并接待K-12科学教师进行夏季研究。此外，旧金山湾区和波多黎各的拉丁裔高中生将得到指导和鼓励，参与STEM活动。最后，研究的内容将被纳入研究生水平的光谱学课程和本科水平的化学过程分离课程。

Intellectual MeritThe development of improved electrocatalysts for renewable fuel production from carbon dioxide (CO2) and water has the potential to enable the long term, sustainable production of storable, transportable fuels. The source of CO2 could be fossil fuel power plant emissions or the atmosphere itself. Although the most cost-effective technological scheme to accomplish this goal remains to be determined, fundamental approaches to accelerate electrochemical reactions could create a path to large-scale processes for sustainable chemical fuels while mitigating CO2 emissions. The goal of the proposed research is to understand factors that govern electrochemical energy conversion processes on transition metal surfaces. Specifically, the proposed research seeks to understand the factors that direct reaction mechanisms, activity, and selectivity for: 1) the electro-reduction of CO2 to produce fuels such as hydrocarbons and alcohols, 2) the electrocatalytic production of H2 from water, and 3) the reverse reactions for the electro-oxidation of fuels such as H2 and alcohols to produce electricity.The fundamental knowledge gained in this work will also enable improvements in efficiency for fuel cells as well as for energy storage devices in which renewable electricity is used to synthesize chemical fuels.In order to understand the factors that govern electrocatalytic energy conversion processes for renewable fuels production, the electronic and geometric structure of metal catalysts will be tailored in order to manipulate surface-adsorbate bond strengths. By this approach, the conversion of key reaction intermediates can be manipulated, leading to significant changes in mechanistic pathways, activity, and selectivity for electrochemical conversion reactions. The reaction chemistry on metals will be tuned by synthesizing a particular metal as a single, pseudomorphic overlayer on a different metal substrate. The electronic structure and lattice constant of the substrate metal will impact key catalyst properties of the metal monolayer resting on top of it. Electrochemical measurements, combined with in-situ atomic-scale imaging (scanning probe microscopy) and in-situ vibrational spectroscopy (tip-enhanced Raman spectroscopy) will gain molecular-level insights regarding surface reaction intermediates, mechanistic pathways, and metal-adsorbate bond strengths. Real-time product analysis coupled an electrochemical cell will also be used to conduct kinetic studies involving isotopes. Broader ImpactsThe proposed education activities will be integrated with the proposed research. Ph.D. students will gain hands-on expertise in catalysis and electrochemical processes for renewable fuels production, which is an emerging area. A team of undergraduate researchers will also be involved in these activities. The educational plan is designed to work with ongoing programs at Stanford University to recruit graduate and undergraduate students from under-represented groups in engineering and host K-12 science teachers to conduct summer research. In addition, Latino high school students in the San Francisco Bay Area and Puerto Rico will be mentored and encouraged to engage in STEM activities. Finally, elements of the research will be incorporated into a graduate-level spectroscopy course and an undergraduate-level chemical process separations course.