CAREER: Understanding the Interdependence of Cation and Anion Adsorption for Electrocatalytic Nitrate Reduction

提供不会对环境造成负面影响的燃料和化学品需要新的催化剂和过程，这些催化剂和过程可以由可再生电力驱动，而不是化石燃料。电催化是一种利用可再生电能驱动低温高压反应的方法，用于分布式可持续燃料生产、废物处理和能量储存。了解电催化反应速率将提高新的电催化工艺的能源效率和经济可行性。这个职业项目将研究电催化将废弃的硝酸盐转化为有价值的产品，如氨，作为可持续化学过程的案例研究。硝酸盐是一种有害污染物，来自工业废水和农业径流，而氨是一种有用的燃料和肥料。为了使电催化硝酸盐转化可行，带负电荷的硝酸根离子必须在带正电荷的阳离子存在的情况下与带电的电催化剂表面相互作用，才能以所需的速率还原硝酸盐。本项目将逐步加入这些因素的复杂性，以加深对影响电催化反应速率的因素的理解。除了研究这种电催化反应模型外，下一代科学家和工程师还将通过课程作业和动手培训，接受向更可持续、更环保的化学经济转变的新挑战的培训。对于电催化来说，反应物、离子和电催化剂之间的复杂相互作用还没有完全被理解。本项目将研究反应分子(即硝酸盐)、阳离子、电催化剂表面和电位在控制硝酸盐还原的电催化速率和选择性方面的相互作用。结构-活性关系将通过测量受控金属和合金表面的反应速率，并与硝酸盐和其他中间体在这些表面上的测量吸附能进行比较来得出。通过紫外-可见光谱、拉曼光谱和X射线吸收光谱研究阳离子与硝酸根离子的相互作用，并与动力学进行比较，确定这些阳离子-阴离子相互作用对吸附能和吸附速率的影响。通过结合所获得的这些相互作用的知识，将提高对废水处理感兴趣的电解液中的硝酸盐电催化还原的理解。这些新的见解将被用于评估连续电催化反应器系统中硝酸盐还原的反应速率。该项目将开发将化学反应堆工程原理应用于电化学反应器的方法，这是今后在可持续化学和燃料生产方面取得进展所必需的。具体的更广泛的影响包括更新现代技术的本科核心课程、电化学应用和工程课程、Chem-E汽车指导和外展，以及利用NSF I-Corps来确定电催化硝酸盐还原的实际应用。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Providing fuels and chemicals without negative environmental impacts requires new catalysts and processes that can be driven by renewable electricity instead of fossil fuels. Electrocatalysis is a method to use renewable electricity to drive low temperature and pressure reactions for distributed sustainable fuel generation, waste treatment, and energy storage. Understanding electrocatalytic reaction rates will increase the energy efficiency and economic viability of new electrocatalytic processes. This CAREER project will study electrocatalysis to convert waste nitrate species to valuable products such as ammonia as a case study for sustainable chemical processes. Nitrate is a harmful pollutant that results from industrial effluents and agricultural runoff, while ammonia is a useful fuel and fertilizer. For electrocatalytic nitrate conversion to be viable, the negatively charged nitrate anion must interact with an electrified electrocatalyst surface in the presence of positively charged cations to reduce nitrate at the desired rates. This project will step-by-step add in the complexity of these factors to develop an understanding of what impacts electrocatalytic reaction rates. In addition to studying this model electrocatalytic reaction, the next generation of scientists and engineers will be trained for the new challenges for a switch to a more sustainable, environmentally friendly chemical economy through coursework and hands on training. The complex interaction of reactants, ions, and the electrocatalyst is incompletely understood for electrocatalysis. This project will study the interplay of the reacting molecule (i.e., nitrate), cations, the electrocatalyst surface, and potential in controlling electrocatalytic rates and selectivities of nitrate reduction. Structure-activity relations will be derived by measuring reaction rates on controlled metal and alloy surfaces and comparing to the measured adsorption energy of nitrate and other intermediates on those surfaces. By studying the interaction of the cations with the nitrate anion through UV-Vis, Raman, and X-ray absorption spectroscopy and comparing to kinetics, how these cation-anion interactions impact the adsorption energies and rates will be identified. The understanding of nitrate electrocatalytic reduction in electrolytes of interest to wastewater treatment will be improved by combining knowledge gained of these interactions. The new insights will be used to evaluate reaction rates for nitrate reduction in continuous electrocatalytic reactor systems. This project will develop methods to apply chemical reactor engineering principles to electrochemical reactors necessary for future advances in sustainable chemical and fuel generation. Specific broader impacts include updating undergraduate core curriculum for modern technologies, an electrochemistry applications and engineering course, Chem-E Car mentorship and outreach, and leveraging NSF I-CORPS to identify practical applications of electrocatalytic nitrate reduction.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.