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

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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.