Circumventing Scaling Relations in Oxygen Electrochemistry using Metal-Organic Frameworks

Abstract

It has been well-established that unfavorable scaling relationships between *OOH, *OH, and *O are responsible for the high overpotentials associated with oxygen electrochemistry. A number of strategies have been proposed for breaking these linear constraints for traditional electrocatalysts (e.g. metals, alloys, metal-doped carbons); such approaches have not yet been validated experimentally for heterogenous catalysts. Development of a new class of catalysts capable of circumventing such scaling relations remains an ongoing challenge in the field. In this work, we use density functional theory (DFT) calculations to demonstrate that bimetallic porphyrin-based MOFs (PMOFs) are an ideal materials platform for rationally-designing the 3D active site environments for oxygen reduction reaction (ORR). Specifically, we show that the *OOH binding energy and the theoretical limiting potential can be optimized by appropriately tuning the transition metal active site, the oxophilic spectator, and the MOF topology. Our calculations predict theoretical limiting potentials as high as 1.07 V for Fe/Cr-PMOF-Al, which exceeds the Pt/C benchmark for 4e ORR. More broadly, by highlighting their unique characteristics, this works aims to establish bimetallic porphyrin-based MOFs as a viable materials platform for future experimental and theoretical ORR studies.

First-Principles Surface Characterization and Water Adsorption of Fe3P Schreibersite

“…In particular, Kohn−Sham density functional theory (DFT) calculations have demonstrated strong ability in accurately reproducing the bulk properties and thermal decomposition of many materials over a broad range of chemical and thermodynamic conditions, 11,26,27 particularly for condensed phases and their surface properties. 28 To this effect, we have performed a series of quantum calculations of the initial steps of schreibersite corrosion in aqueous systems on its most stable facet. We first discuss results regarding our choice of DFT basis set size and other parameters in terms of the predicted bulk lattice constants, electron density of states, bulk modulus, and low index surface energies.…”

Semi-Automated Creation of Density Functional Tight Binding Models through Leveraging Chebyshev Polynomial-Based Force Fields

“…DFT calculations, though, require immense computational effort per simulation time step and consequently are usually limited to picosecond time scales and nanometer system sizes. In contrast, many processes of interest have properties that can span orders of magnitude larger scales, including large-scale carbon heterocycle synthesis, 5 the rational design of 3D materials, 6 and defect formation and grain boundary interactions in crystalline systems. 7 Hence, there is a great need to explore methods that can harness the accuracy of DFT while yielding substantial improvements in computational speeds.…”

First-principles surface characterization and water adsorption of Fe3P schreibersite

“…In particular, Kohn-Sham Density Functional Theory (DFT) calculations have demonstrated strong ability in accurately reproducing the bulk properties and thermal decomposition of many materi-als over a broad range of chemical and thermodynamic conditions, 11,26,27 particularly for condensed phases and their surface properties. 28 To this effect, we have performed a series of quantum calculations of the initial steps of schreibersite corrosion in aqueous systems on its most stable facet. We first discuss results regarding our choice of DFT basis set size and other parameters in terms of the predicted bulk lattice constants, electron density of states, bulk modulus, and low index surface energies.…”