EAGER: Periodic Binding Energy Modulation for Electrochemical Systems

University Of Massachusetts Amherst, Amherst MA

Investigators

Abstract

Catalysts are materials that accelerate chemical reactions and thereby reduce the cost, energy consumption, and capital equipment demands of chemical manufacturing processes. Most catalyst research focuses on discovering combinations of materials that are optimal for accelerating the targeted reaction. Fundamental limitations exist, however, regarding the extent to which materials alone can accelerate reactions. The study will side-step such materials limitations by introducing dynamic perturbations to the catalyst's operating conditions at the timescale of reaction events. The radically new concept will be demonstrated on the water splitting reaction - an important reaction for generating hydrogen by renewable means. Preliminary theoretical analysis has suggested that reaction rates can be increased by orders of magnitude via the dynamic perturbations, while also opening the door to less expensive catalysts for a wide range of chemical reactions. The catalytic activity of materials is dictated by the binding energetics of key reaction intermediates, described through energy scaling relationships, which predicts a maximum in the catalytic activity - characterized by the well-known Sabatier principle - achievable through only material design. The electrochemical splitting of water to produce renewable hydrogen suffers from this limitation, where rates of hydrogen evolution reactions are dictated by the binding energy of hydrogen. The problem is further exacerbated by the fact that optimal hydrogen binding energies are found on precious metal catalysts, placing strain on an already economically challenging process. The study will investigate the extent to which the application of periodic oscillations in applied potential, on the timescale of turnover events, can alter the binding energetics of hydrogen on the electrode surface. Operating catalysts under a constantly oscillating applied potential, where binding energetics of reaction intermediates are constantly changing, allows a single catalyst to mimic the performance of multiple materials in a periodic fashion. This will allow for the design of catalysts that break past the current limitations imposed by scaling relationships, to reach unprecedented levels of catalytic activity. Implementing this transformative method of operation is currently limited by our experimental ability to alter binding energetics on catalytic materials with precision under reaction conditions. Specifically, the project will explore the use of alternating potentials in standard electrochemical cells for efficient water splitting. This experimental design will also be used to investigate coupling thermocatalysis with electrochemical systems that serve as a binding energy modulation platform. The approach is potentially applicable to a broad range of catalytic reactions of commercial and environmental importance. The dynamic catalysis concept will also be introduced to graduate students via an elective course developed by the principal investigator. 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.