CAREER: Real-time control of elementary catalytic steps: Controlling total vs partial electrocatalytic oxidation of alkanes and olefins

碳氢化合物是由氢和碳原子组成的分子，是对人类最重要的化学物质之一。碳氢化合物主要由天然气和石油提供，通过燃烧提供了我们大部分的能源需求，也是许多制成品的来源，包括塑料、润滑剂、织物和建筑材料等。不幸的是，传统的高温燃烧和制造工艺难以控制，导致能源效率低，二氧化碳（CO2）排放高，并产生不希望的副产品（后者由于需要下游分离而使工艺复杂和能源效率低下）。该项目探索了一种新的电催化碳氢化合物利用方法，该方法在室温下操作，控制了将氧原子纳入碳氢化合物的基本步骤，从而大大提高了燃烧效率，而含氧碳氢化合物产品的化学制造可以更有效地导向所需的产品，从而降低了能耗。除了技术上的好处，该项目还将努力使学生和公众更容易理解电化学过程。为此，该项目包括一种使电化学界面行为可听的方法，从而将这些“电化学声音”作为在大学和高中教授电化学的工具。该项目是建立在观察碳氢化合物氧化反应的低效率和选择性的起源源于催化反应途径中涉及的每个基本步骤所需的巨大不同的条件。控制氧化要求底物以正确的结合方式吸附，中间体氧化为所需产物，产物脱附而不引起进一步的反应。然而，有利于一步的条件往往不利于另一步。该项目通过按照反应步骤的顺序调节施加在电催化剂上的电压来解决这一挑战，从而重新排列电催化剂和电解质之间形成的电化学界面。从而实现独立控制，依次增强碳氢化合物的吸附，吸附化合物的氧化和所需产物的脱附。动态电位调制方法的有效性将在烷烃燃料电池应用和可持续合成含氧塑料前体化学品中进行检验。总之，这些努力将为有效生产化学品开辟新的途径，同时帮助美国化学工业向清洁能源过渡。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Hydrocarbons, molecules which consist of hydrogen and carbon atoms, are some of the most important chemicals to humanity. As supplied primarily by natural gas and oil, hydrocarbons provide most of our energy needs through combustion, and also serve as the source of many manufactured products, including plastics, lubricants, fabrics, and building materials, among others. Unfortunately, traditional high-temperature combustion and manufacturing processes are challenging to control, resulting in low energy efficiency, high emissions of carbon dioxide (CO2), and generation of undesired side products (the latter compounding process complexity and energy inefficiency through the need for downstream separations). The project explores a novel electrocatalytic approach to hydrocarbon utilization that operates near room temperature and controls the elementary steps involved in incorporating oxygen atoms into hydrocarbons such that combustion efficiency is greatly improved, while chemical manufacturing of oxygen-containing hydrocarbon products can be directed more effectively to desired products, resulting in lower energy consumption. Aside from the technical benefits, the project will be complemented by efforts to make the understanding of electrochemical processes more accessible to students and the general public. To this effect, the project includes an approach to make the behavior of electrochemical interfaces audible, thus employing these ‘electrochemical sounds’ as a tool to teach electrochemistry at the university and high school levels. The project is built on the observation that the origin of low efficiency and selectivity in hydrocarbon oxidation reactions derives from the vastly different conditions needed for each of the elementary steps involved in the catalytic reaction pathway. Controlled oxidation requires substrate adsorption in the correct binding mode, oxidation of intermediates to the desired product, and product desorption without inducing further reaction. Yet, conditions favoring one step often disfavor another. The project addresses this challenge by modulating the voltage applied to the electrocatalyst in sequence with the reaction steps, thereby rearranging the electrochemical interface formed between the electrocatalyst and the electrolyte. Independent control is thus achieved to sequentially enhance hydrocarbon adsorption, the oxidation of adsorbed compounds, and the desorption of desired products. The efficacy of the dynamic potential modulation approach will be examined in an alkane fuel cell application and in the sustainable synthesis of oxygenated precursor chemicals for plastics. Taken together, these efforts will open novel avenues to the efficient production of chemicals, while aiding the clean energy transition of the U.S. chemical industry.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.