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

在化学系大分子、超分子和纳米化学项目的支持下，斯科特·M·维克森林大学的盖耶正在开发新的方法来制造非常小的催化剂纳米颗粒，将二氧化碳（一种导致气候变化的温室气体）选择性地转化为对工业有价值的化学品。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控制金属原子之间间距的方法。金属层也被追求以进一步控制催化剂与二氧化碳的相互作用，同时还限制高催化活性所需的贵金属的量。所开发的化学方法有可能产生高效的催化剂，并影响还原电催化的重要领域，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粒子。Geyer盖耶将继续参与和教育更广泛的社区关于可持续能源通过协调当地的课后计划，为学生提供实践经验收集和转换成有形的产品，如声音，运动，和化学燃料。该计划还带来了一个现场移动的研究实验室，以便社区成员可以使用科学设备。本研究的重点是使用胶体合成方法来探讨化学计量和异质结构对金属磷化物催化剂对二氧化碳还原反应的选择性的作用。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种途径，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应该提供一种替代的合成路线，以新的材料和建立化学计量的作用，实现有效的阳离子交换。了解化学计量如何影响选择性使用实验和计算方法有可能使选择性催化剂表面的更合理的设计。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（如氢气还原、氮气还原和氧气析出）开辟一系列新的异质结构催化剂。该奖项反映了NSF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.