Employing Atomically Precise Colloidal Synthesis to Reveal the Roles of Stoichiometry, Strain and Electron Density in Metal Phosphide Electrocatalysts

在化学学部大分子、超分子和纳米化学项目的支持下，威克森林大学的斯科特·m·盖耶博士正在开发制造非常小的催化剂纳米颗粒的新方法，这种纳米颗粒可以将导致气候变化的温室气体二氧化碳选择性地转化为对工业有价值的化学物质。为了更好地理解纳米颗粒表面促进特定化学物质产生的方式，正在开发使用少量磷来控制金属原子之间间距的方法。为了进一步控制催化剂与二氧化碳的相互作用，同时限制高催化活性所需的贵金属的数量，金属分层也正在研究中。所开发的化学方法有可能产生有效的催化剂，并影响还原性电催化的重要领域，同时也有助于将可再生方法应用于增值燃料和工业化学品的更广泛领域。通过这项研究，本科生和研究生将学习如何合成和表征催化纳米颗粒。Geyer博士将继续参与并教育更广泛的社区，通过协调当地的课后项目，为学生提供收集和将能量转化为有形产品（如声音，运动和化学燃料）的实践经验。这个项目还带来了一个移动研究实验室，这样社区成员就可以使用科学设备工作。研究重点是利用胶体合成方法探讨化学计量学和异质结构对金属磷化物纳米晶催化剂对二氧化碳还原反应选择性的影响。例如，开发一种可靠的金属磷化物的核/壳合成方法有望为外延生长提供一条途径，以实现核和壳材料之间的化学计量转移。此外，开发磷化铜和磷化银作为交换模板将为新材料的合成提供另一种途径，并建立化学计量学在实现高效阳离子交换中的作用。利用实验和计算方法了解化学计量学如何影响选择性，有可能使更合理的设计选择性催化剂表面成为可能。开发强大的金属磷化物核壳合成技术可能会为二氧化碳还原以及其他电催化反应（如氢还原、氮还原和析氧）开辟广泛的新型异质结构催化剂。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。

With the support of the Macromolecular, Supramolecular, and Nanochemistry Program in the Division of Chemistry, Dr. Scott M. Geyer of Wake Forest University is developing new methods to make very small catalyst nanoparticles that convert carbon dioxide, a greenhouse gas that contributes to climate change, selectively into chemicals valuable to industry. To better understand the way in which the nanoparticle surface promotes the creation of a specific chemical, methods to control the spacing between metal atoms using small amounts of phosphorus are being developed. Metal layering is also being pursued to further control the interaction of the catalyst with carbon dioxide while also limiting the amount of precious metal required for high catalytic activity. The chemical methods developed have the potential to result in efficient catalysts and impact the important field of reductive electrocatalysis, while also contributing to the broader area of renewable approaches into value-added fuels and industrial chemicals. Through this research, undergraduate and graduate students will learn how to synthesize and characterize catalytic nanoparticles. Dr. Geyer will continue to engage and educate the broader community about sustainable energy by coordinating a local after school program that provides students with hands on experience collecting and converting energy into tangible products such as sound, movement, and chemical fuels. This program also brings a mobile research laboratory on site so community members can work with scientific equipment.The research focuses on using colloidal synthetic methods to probe the role of stoichiometry and heterostructure on the selectivity of metal phosphide nanocrystal catalysts toward the carbon dioxide reduction reaction. For example, the development a reliable core/shell synthesis method for metal phosphides is expected to provide a route for epitaxial growth to achieve stoichiometric transfer between the core and shell materials. Further, developing copper phosphide and silver phosphide as exchange templates should provide an alternative synthetic route to novel materials and establish the role of stoichiometry in achieving efficient cation exchange. Understanding how stoichiometry impacts selectivity using experimental and computational methods has the potential to enable more rational design of selective catalyst surfaces. Developing robust metal phosphide core/shell synthetic techniques may open a wide range of new heterostructure catalysts of interest for carbon dioxide reduction as well as for other electrocatalytic reactions such as hydrogen reduction, nitrogen reduction, and oxygen evolution.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.