Professors Charles McCrory and James Penner-Hahn of the University of Michigan-Ann Arbor are supported by the Macromolecular, Supramolecular, and Nanochemistry Program of the NSF Division of Chemistry to study the sequence of events (mechanisms) that cause single layer films of organic molecules on solid surfaces (self-assembled monolayers, or SAMs) to detach from the surface under electrochemical operating conditions. The process, which is called reductive desorption, is poorly understood. A better understanding of the process paves the way for the design of more robust SAM systems. A combination of electroanalytical techniques, advanced X-ray and IR spectroscopies are used to provide insight into the mechanism of desorption. Robust SAMs are critical for many practical applications, including their use to anchor catalysts for reactions relevant to energy and environmental chemistry, such as carbon dioxide reduction for solar fuels generation and nitrate reduction for wastewater remediation. This project also provides a platform to promote scientific literacy through formal training of student researchers in communicating to the general public, active engagement with the local community through interactive demonstrations of the concepts of catalysis and corrosion, and hosting Detroit high school students in summer research internships at the University of Michigan.
The use of well-defined self-assembled monolayers (SAMs) to tether molecular catalysts to electrode surfaces facilitates the careful mechanistic, kinetic, and spectroelectrochemical studies needed for new catalyst development. However, the use of SAMs for tethering electrocatalysts to electrode surfaces for reactions of societal importance, such as carbon dioxide reduction and nitrate reduction, is limited by the reductive instability of thiol-based SAMs on gold and other metal surfaces. The discovery of reductively-stable SAMs for the direct immobilization of molecular catalysts to metallic surfaces is an enabling technology in molecular electrocatalysis that may facilitate careful and complete mechanistic and kinetic analysis of known and emerging electrocatalysts. Currently, a lack of mechanistic understanding of the reductive desorption process limits the rational design of new, more-reductively stable systems. This project uses a combination of electroanalytical techniques and advanced X-ray and infrared spectroscopies to probe the electronic and physical structures of self-assembled monolayers during the reductive desorption process, providing insights into the mechanism of reductive desorption. The results of these mechanistic studies may facilitate the rational design of new, more reductively-stable SAMs that enable the immobilization and in situ spectroelectrochemical study of electrocatalysts for multi-electron transformations important to energy and environmental chemistry.
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.
