Bottom-up design of earth-abundant catalysts for reversible hydrogen oxidation and reduction in alkaline electrolytes

氢气是工业化学的重要原料，也是一种潜在的低成本可再生能源储存媒介。在酸性电解液中，铂等催化剂上的氢氧化(HOR)和析氢(HER)反应都非常快，但在碱性电解液中反应很慢。这项研究旨在找出碱性pH对氢电催化不利影响的原因，并利用由此得出的见解，利用地球上丰富的材料设计活性HER/HOR电催化剂，从而使低成本燃料电池和电解槽技术得到更广泛的应用。这项工作将支持研究生和本科教育，以及对高中生的推广，所有这些都是为了更广泛地了解和欣赏电化学的机会，为可持续的能源和化学生产方法做出贡献。长期以来，氢电极的研究在发展电化学和电催化的核心概念方面发挥了关键作用。氢结合能(HBE)通常被认为是控制反应活性的因素，而水在确定反应动力学和反应途径中的作用往往被忽视。这项研究应用了一套独特的实验技术和理论分析来隔离碱性氢电化学中个别现象的影响。可控应变的均匀表面将被用来研究pH对HBE的影响。电化学石英晶体微天平和CO置换测量将被用来观察表面吸附的氢氧化物，所得到的信息将与常规的电化学实验和微动力学模型相结合，以确定氢氧化物在表面掺杂催化剂上进行的碱性氢反应中的作用。此外，催化剂载体将不同，以确定水取向的影响。所获得的基本见解将被用于合成基于富含地球的元素的活性、稳定的电催化剂。了解pH对吸附能和活化势垒高度的影响，不仅对燃料电池和可再生能源储存，而且对其他经济和环境重要的电化学过程，如腐蚀、二氧化碳还原、燃料的直接氧化、液流电池、氨合成和生物氧化系统，都将提供重要的见解。该项目将为两名博士生和几名本科生提供广泛的跨学科研究经验，包括电化学方法、表面科学以及材料合成和表征方面的培训。在这项工作的同时，PI将为德雷克塞尔大学的新生设计课程开发以电化学为中心的教育模块，包括与当地高中编程女孩俱乐部的分会合作。

Hydrogen is a critical feedstock for industrial chemistry and a potential low-cost medium for renewable energy storage. Both the hydrogen oxidation (HOR) and evolution (HER) reactions are extremely fast on platinum and other catalysts in acidic electrolytes, but sluggish in alkaline electrolytes. The research aims to identify the reasons for the adverse effects of alkaline pH on hydrogen electrocatalysis and use the resulting insight to design active HER/HOR electrocatalysts from earth-abundant materials, thereby enabling broader utilization of low-cost fuel cell and electrolyzer technologies. The work will support graduate and undergraduate education, and outreach to high school students, all directed toward broader understanding and appreciation of opportunities for electrochemistry to contribute to sustainable methods for the production of energy and chemicals.Study of the hydrogen electrode has long played a key role in the development of core concepts in electrochemistry and electrocatalysis. Hydrogen binding energy (HBE) is usually assumed to control reactivity, and the role of water in defining reaction kinetics and pathways is often overlooked. This study applies a unique suite of experimental techniques and theoretical analyses to isolate the effects of individual phenomena in alkaline hydrogen electrochemistry. Controllably strained, homogeneous surfaces will be used to investigate the effect of pH on HBE. Electrochemical quartz crystal microbalance and CO displacement measurements will be used to observe surface-adsorbed hydroxide, and the resulting information will be combined with conventional electrochemical experiments and microkinetic models to identify the role of hydroxide in the alkaline hydrogen reactions conducted on surface-doped catalysts. In addition, catalyst supports will be varied to determine the impact of water orientation. The fundamental insight gained will be used to synthesize active, stable electrocatalysts based on earth-abundant elements. Understanding the effects of pH on adsorption energy and activation barrier heights will provide important insight, not only for fuel cells and renewable energy storage, but for other economically and environmentally important electrochemical processes such as corrosion, carbon dioxide reduction, direct oxidation of fuels, flow batteries, ammonia synthesis and biological redox systems. The project will provide two PhD students and several undergraduate students with a broad and interdisciplinary research experience with training in electrochemical methods, surface science, and materials synthesis and characterization. In conjunction with the work, the PIs will develop electrochemistry-centered educational modules for Drexel University's Freshman Design course, including collaboration with a local high school's chapter of the Girls Who Code club.