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

氢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介质。在酸性电解质中，铂和其他催化剂上的氢氧化（HOR）和析氢（HER）反应都非常快，而在碱性电解质中反应缓慢。该研究旨在确定碱性pH对氢电催化不利影响的原因，并利用由此产生的见解来设计地球上丰富材料的活性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，并向高中生推广，所有这些都是为了更广泛地理解和欣赏电化学为能源和化学品生产的可持续方法做出贡献的机会。长期以来，氢电极的研究在电化学和电催化核心概念的发展中起着关键作用。氢结合能（HBE）通常被认为控制反应活性，而水在定义反应动力学和途径中的作用往往被忽视。本研究采用一套独特的实验技术和理论分析来分离碱氢电化学中个别现象的影响。可控应变、均匀表面将用于研究pH对HBE的影响。电化学石英晶体微天平和CO位移测量将用于观察表面吸附的氢氧化物，并将所得信息与常规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，催化剂载体也会有所不同，以确定水取向的影响。所获得的基本见解将用于合成基于地球丰富元素的活性，稳定的电催化剂。了解pH对吸附能和激活势垒高度的影响将提供重要的见解，不仅对燃料电池和可再生能源存储，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，燃料直接氧化，液流电池，氨合成和生物氧化还原系统。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、材料合成和表征方面的培训。与此同时，pi将为Drexel大学的大一设计课程开发以电化学为中心的教育模块，包括与当地高中的Girls Who Code俱乐部分会合作。

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.