CAS: Rational Design of Earth-Abundant Phosphide Hydrogen Evolution Catalysts

在化学系化学催化项目的资助下，来自爱荷华州州立大学的Kovnir和约翰逊博士正在解决一个关键的社会经济问题：对化石燃料的强烈依赖。为此，他们的研究小组正在研究通过电解从水中生产氢气。为了通过电解有效且经济地生产氢气，需要改进的电极材料，称为电催化剂。这个联合实验和计算项目提供了一个基本的理解，即如何修改具有明确性质和结构的电催化剂以提高其性能。他们对电催化剂的合作和综合合成，结构和表面研究为学生研究人员提供了独特的培训和教育体验。参与该项目的学生包括本科生和高中生。 Kovnir博士和约翰逊博士还致力于扩大代表性不足的少数民族参与其研究，包括例如ACS经济困难高中生暑期研究实习方案。Kovnir博士正在为本科生开发可持续材料的暑期研究项目，本科生和研究生正在学习如何通过化学学习社区外展向公众传播科学。氢气是一种可持续燃料，目前通过催化蒸汽重整（和甲烷燃烧）生产，这会损害所有环境效益。通过水的催化电解释放氢气，如果与可再生能源相结合，是未来解决这个问题的方法。虽然非均相催化剂占世界生产总值的20%，但为了可持续和廉价，需要基于地球丰富元素的电催化剂。近年来，大量的第一行过渡金属（铁或镍）形成的纳米磷化物已被证明是有前途的析氢反应（HER）的电催化剂。这些电催化纳米颗粒的表面很难精确控制和表征，因为纳米颗粒上的每个晶面具有不同的原子键合和反应性。因此，由于反应涉及许多方面，人们对为什么某些催化剂比其他催化剂更好缺乏基本的理解，并且通常是偶然发现新的催化剂。由于每个表面小面的结构是由体相的晶体结构定义的，爱荷华州州立大学的科夫尼尔和约翰逊博士正在通过体过渡金属磷化物中化学键合模式的交替来研究表面活性位点的电子行为。具有可调反应性的过渡金属磷化物模型催化剂的本体结构、原位表面（晶面依赖）结构和电催化性能之间的基本关系正在建立。在化学部化学催化计划的资助下，这些研究将有助于发现改进的，更便宜的和环境可持续的HER电催化剂。Kovnir和约翰逊博士积极参与学生参与他们的研究，包括高中和本科生，以及来自代表性不足群体的学生。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

With funding from the Chemical Catalysis Program of the Division of Chemistry, Drs. Kovnir and Johnson from Iowa State University are addressing a key socioeconomic problem: the strong dependence on fossil fuels. To that end, their research groups are studying the production of hydrogen from water via electrolysis. To produce hydrogen efficiently and economically by electrolysis improved electrode materials, known as electrocatalysts, are needed. This joint experimental and computational project is providing a fundamental understanding of how electrocatalysts with well-defined properties and structures can be modified to enhance their performance. Their collaborative and integrative synthetic, structural, and surface studies of electrocatalysts are providing a unique training and educational experience for student researchers. Students involved in the project include undergraduate and high-school students. Drs. Kovnir and Johnson are also engaged in broadening participation of underrepresented minorities in their research, including for example the ACS Summer Research Internship Program for Economically Disadvantaged High School Students. Dr. Kovnir is developing summer research projects to for undergraduate on sustainable materials and the undergraduate and graduate students are learning how to communicate science to the public through the Chemistry Learning Community outreach.Hydrogen is a sustainable fuel that is currently produced by catalyzed steam reforming (and burning of methane), which compromises all environmental benefits. Releasing hydrogen via catalytic electrolysis of water, if coupled with renewable energy sources, is a future solution to this issue. Although heterogeneous catalysts accounts for 20% of the Gross World Product, to be sustainable and cheap, electrocatalysts based on earth-abundant elements are required. Recently, nanoparticle phosphides formed with abundant first-row transition-metals (Iron or Nickel) have been shown to be promising electrocatalysts for the hydrogen evolution reaction (HER). The surface of these electrocatalytic nanoparticles is difficult to control precisely and characterize, because each crystal facet on a nanoparticle has different atomic bonding and reactivity. Unsurprising then, with many facets participating in reactions, there is lack of fundamental understanding as to why some catalysts are better than others, and, more often than not, serendipity discovers new catalysts. Given that the structure of each surface facet is defined by the crystal structure of the bulk phase, Drs. Kovnir and Johnson of Iowa State University are studying the electronic behavior of the surface-active sites by the alternation of chemical bonding patterns in the bulk transition-metal phosphides. Fundamental relationships are being established between bulk structure, in-situ surface (crystal facet-dependent) structure, and electrocatalytic performance of model transition-metal–phosphide catalysts with tunable reactivities. With funding from the Chemical Catalysis Program in the Division of Chemistry these studies will aid progress toward the discovery of improved, cheaper, and environmentally sustainable HER electrocatalysts. Drs. Kovnir and Johnson are actively engaged in student participation in their research, including high school and undergraduate students, and students from underrepresented groups. Summer research and science communication opportunities are also being provided for these students.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.