2018 AFOSR MURIMolecular Level Studies of Solid-Liquid Interfaces in Electrochemical ProcessesPO: Dr. Michael Berman, Molecular Dynamics and Theoretical Chemistry: mdtc@us.af.mil PI: Tianquan (Tim) Lian, Department of Chemistry, Emory UniversityWebsite: TBD
The efficient interconversion of electrical and chemical energy requires functional electrodes that are able to catalyze complex multi-electron energy conversion reactions. The electrodes in energy conversion devices must, therefore, serve not merely as inert sources or sinks of electrons but rather as active players that bind reactants, stabilize key intermediates, and enable inner-sphere electron transfer (ISET) reactions. Despite its fundamental and technological importance, a molecular-level mechanistic understanding of the factors that drive efficient multi-electron innersphere electrocatalysis remains elusive, impeding systematic progress toward innovative and more efficient energy conversion technologies. This critical knowledge gap arises because the currentvoltage response of an electrode provides little information about the complex array of elementary surface processes that underpin near all energy conversion reactions. Addressing this longstanding grand challenge requires multi-faceted methodologies that go beyond classical current-voltage measurements and combine operando probes and atomistic simulations to develop multiscale models of critical ISET reactions.
The proposed MURI program is a multidisciplinary effort aimed at developing a molecularlevel understanding of the fundamental processes that drive complex electrochemical reactions. This research will be carried out as a collaborative effort between Emory University (T. Lian, Lead PI), Cornell University (H. D. Abruña), Massachusetts Institute of Technology (Y. Surendranath and A. Willard), University of Pennsylvania (J. Subotnik), University of Southern California (J. Dawlaty), and Yale University (S. Hammes-Schiffer and J. Mayer).
The proposed MURI program contains five closely integrated Thrusts. i) Thrust 1: to develop a multimodal electrochemical/spectroscopic platform for operando molecular-level investigations of electrochemical processes, integrating the high sensitivity of electrochemical methods, the quantification of mass spectrometry, and the chemical sensitivity and temporal resolution of spectroscopic methods. ii) Thrust 2: to develop first principles, atomistic simulation methods for describing elementary inner-sphere reactions, including interfacial double layer effects, at electrochemical interfaces. A key component of this thrust is to create an open-source software package for simulating electrochemical phenomena with sophisticated microkinetic models that will be parametrized with first principles methods and experimental inputs obtained from the multi-modal electrochemical platform. iii) Thrust 3: to model fundamental inner-sphere reactions and develop a molecular-scale understanding of the interfacial environment, especially under operating (non-equilibrium) conditions, that will be of broad relevance to all electrochemical applications. iv) Thrust 4: to apply the tools developed and the fundamental insights gained in Thrusts 13 to a case study of the electrochemical oxidation of methanol, establishing the mechanistic factors that drive selective and efficient complete oxidation of methanol to carbon dioxide, a longstanding goal in both fundamental and practical electrocatalysis. v) Thrust 5: to tackle a recalcitrant electrocatalysis problem, namely the complete electrooxidation of ethanol, including the very demanding C–C bond cleavage step, a holy grail in electrocatalysis.
The anticipated outcome of this MURI program will be a transformative molecular-level understanding of electrochemical phenomena, as well as widely accessible multimodal experimental platforms and advanced theoretical tools for understanding, optimizing, and designing next generation electrochemical technologies that are essential to DoD missions.