(Invited) Electrocatalysis from First-Principles: Reaction Mechanisms and Ideas for Improved Materials

Abstract

Density Functional Theory (DFT) has enabled the search for improved electrocatalysis, based on DFT-identified reactivity descriptors for a wide variety of reactions and surfaces1, 2. Concurrently, the inorganic synthesis community has achieved important successes towards the robust synthesis of shape-selected nanocrystals which preferentially expose certain facets and morphologies3, 4. We start this presentation by discussing our work on the structure sensitivity of ammonia electrooxidation on transition metals in alkaline fuel cells; the kind of fuel cells that Dr. S. Gottesfeld has passionately investigated for many years5. We explain the higher activity of Pt(100) versus Pt(111), and propose the binding energy of atomic nitrogen as a key reactivity descriptor for this environmentally-benign electrochemistry6. We will then present some of our work on acidic fuel cells, especially regarding the electrooxidation of formic acid on transition metals7, and, with time permitting, on Pt and Pd monolayers on transition metals. Unlike ammonia electrooxidation, we here propose two reactivity descriptors (the free energy of adsorbed CO* and the free energy of adsorbed OH*) to adequately describe the search space for improved catalysts for formic acid electrooxidation. [1] T. Bligaard, J. K. Nørskov Electrochim. Acta. 2007, 52, 5512-5516. [2] J. K. Nørskov, F. Abild-Pedersen, F. Studt, T. Bligaard Proc. Natl. Acad. Sci. U.S.A. 2011, 108, 937-943. [3] A. Ruditskiy, S.-I. Choi, H.-C. Peng, Y. Xia MRS Bull. 2014, 39, 727-737. [4] A. Ruditskiy, H. C. Peng, Y. N. Xia Ann. Rev. Chem. Biomol. Eng. Vol 7. 2016, 7, 327-348. [5] S. Gottesfeld, D. R. Dekel, M. Page, C. Bae, Y. S. Yan, P. Zelenay, Y. S. Kim J. Power Sources. 2018, 375, 170-184. [6] J. A. Herron, P. Ferrin, M. Mavrikakis J. Phys. Chem. C. 2015, 119, 14692-14701. [7] A. O. Elnabawy, J. A. Herron, J. Scaranto, M. Mavrikakis J. Electrochem. Soc. 2018, 165, J3109-J3121.