Current research
- Computational heterogeneous catalysis and electrocatalysis
- Microkinetic modeling
- Metal Organic Framework Nucleation and Crystallization
Overview
Research in the Schmidt group utilizes the tools of theoretical and computational chemistry to address both fundamental and applied research questions of broad relevance to energy and catalysis. Specifically, we are focused on understanding the properties of complex materials with energy applications, including: heterogeneous catalysts / electrocatalysts; and nano-porous materials. We both develop new methodologies, and employ existing computational methods, using a diverse set of tools including classical molecular simulations, electronic structure calculations, and machine learning methods.
A significant research focus of the group is current on computational electrocatalysis, featuring two ongoing highly collaborative projects. With Prof. Song Jin, we are currently examining the selective 2e- reduction of oxygen to hydrogen peroxide, which presents stringent selectivity challenges due to the competing (and strongly thermodynamically favored) 4e- reduction to water. In collaboration with Prof. Kyoung-Shin Choi, we are examining the selective reduction of biomass molecules, which presents a selectivity challenge due to the presence of multiple reducible groups. In both cases, we are using a combination of plane-wave density functional theory to examine the thermodynamics and kinetics of the competing reaction steps. Using microkinetic models, we make direct connection with experimentally measured currents, Faradiac efficiencies, and product accumulations. Beyond standard approaches, the group is also interested pursing new approaches for more accurately modeling reactivity at electrified aqueous interfaces.
Computational modeling of ORR on the CoS2 (100) surface. (a) Free energy diagram for both 2e– and 4e– ORR at the calculated standard equilibrium reduction potential of 2e– ORR. (b) Top view of (b) the CoS2 surface with adsorbed OOH* and (c) the transition state for OOH* scission. (d) Side view of the CoS2 surface with adsorbed OOH*. Reproduced from https://doi.org/10.1021/acscatal.9b02546.
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In an alternative direction, the group also maintains its historical focus on nano-porous materials, and specifically metal-organic frameworks (MOFs). Earlier research efforts focused largely on modeling the gas adsorption properties of porous MOFs, often using novel physics-based force fields to provide highly accurate and predictive models. More recently, our efforts have focused on modeling the crystal nucleation and growth of MOFs and other very weak electrolytes. To this end, we have been developing new methods to model the nucleation and growth of crystalline materials from solution, including those based on Monte Carlo methods, graph-theory, and even micro-kinetic models. A long-term goal of this direction is to provide a qualitative understanding of how various synthetically controllable parameters (temperature, solvent, supersaturation...) control the outcomes of the crystallization process, especially in the face of competing crystalline polymorphs.
(a) Nucleation free energy surface analysis and cluster structures. The red solid line is the nucleation free energy surface at 2.68 M. The blue dashed line is a parabolic fit in the region close to the free energy barrier at a critical cluster size. Snapshots of clusters with N = 8, 13, and 24 ion pairs are shown on top of the free energy curve. Na+ and Cl– are colored in blue and green, respectively. (b) Ion probability density with respect to coordination number and the Steinhardt parameter, Q6: (top to bottom) clusters of sizes 8, 13, and 24 and the bulk crystal. Reproduced from https://doi.org/10.1021/acs.jctc.9b00743 |