The Kitchin Research Group

A collaborative paper with our colleagues at NETL and U. Pitt. was just accepted in RSC Advances

cite:thompson-2014-co2-react

Copyright (C) 2014 by John Kitchin. See the License for information about copying.

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Identifying Potential BO2 Oxide Polymorphs for Epitaxial Growth Candidates, by Prateek Mehta, Paul A. Salvador, and John R. Kitchin http://pubs.acs.org/doi/full/10.1021/am4059149

Transition metal dioxides (BO2) exhibit a number of polymorphic structures with distinct properties, but the isolation of different polymorphs for a given composition is carried out using trial and error experimentation. We present computational studies of the relative stabilities and equations of state for six polymorphs (anatase, brookite, rutile, columbite, pyrite, and fluorite) of five different BO2 dioxides (B = Ti, V, Ru, Ir, and Sn). These properties were computed in a consistent fashion using several exchange correlation functionals within the density functional theory formalism, and the effects of the different functionals are discussed relative to their impact on predictive synthesis. We compare the computational results to prior observations of high-pressure synthesis and epitaxial film growth and then use this discussion to predict new accessible polymorphs in the context of epitaxial stabilization using isostructural substrates. For example, the relative stabilities of the columbite polymorph for VO2 and RuO2 are similar to those of TiO2 and SnO2, the latter two of which have been previously stabilized as epitaxial films.

As with other recent papers, the supporting information file contains embedded data files that enable the reproduction of the data and figures in the paper.

Copyright (C) 2014 by John Kitchin. See the License for information about copying.

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Three new M.S. students have joined the Kitchin Research Group! We are pleased to welcome Wenqin You, Meiheng Lu, and Nitish Govindarajan!

Wenqin will work on modeling CO2 capture processes, Meiheng will work on a data sharing project, and Nitish will use density functional theory to model oxide materials relevant to SOFCs and CO2 conversion.

Copyright (C) 2014 by John Kitchin. See the License for information about copying.

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Three new PhD students have joined the Kitchin Research Group! We are pleased to welcome Mehak Chawla, Qingqi (Victor) Fan, and John Michael (co-advised by Professor Paul Sides) to the group.

Mehak joins us from The Ohio State University. She will be using density functional theory to model metal alloy and oxide surface reactivity.

John completed his B.S. in Chemical Engineering at Miami University (OH). He will be using the imaging ammeter to screen electrocatalysts. He will be co-advised by Dr. Sides.

Victor joins us from the University of Tulsa. He will be studying oxygen evolution electrocatalysis on transition metal oxides.

Copyright (C) 2013 by John Kitchin. See the License for information about copying.

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Simulating Temperature Programmed Desorption of Oxygen on Pt(111) Using DFT Derived Coverage Dependent Desorption Barriers Spencer D. Miller, Vladimir V. Pushkarev, Andrew J. Gellman, John R. Kitchin http://link.springer.com/article/10.1007/s11244-013-0166-3 Abstract The dissociative adsorption energy of oxygen on Pt(111) is known to be coverage dependent. Simple Redhead analysis of temperature programmed desorption (TPD) experiments that assumes a coverage independent desorption barrier can lead to errors in estimated properties such as desorption barriers and adsorption energies. A simple correction is to assume a linear coverage dependence of the desorption barrier, but there is usually no formal justification given for that functional form. More advanced TPD analysis methods that are suitable for determining coverage dependent adsorption parameters are limited by their need for large amounts of high quality, low noise data. We present a method to estimate the functional form of the coverage dependent desorption barrier from density functional theory calculations for use in analysis of TPD spectra. Density functional theory was employed to calculate the coverage dependence of the adsorption energy. Simulated TPD spectra were then produced by empirically scaling the DFT based adsorption energies utilizing the Bronstead-Evans-Polyani relationship between adsorption energies and desorption barriers. The resulting simulated spectra show better agreement with the experimental spectra than spectra predicted using barriers that are either coverage-independent or simply linearly dependent on coverage. The empirically derived scaling of the desorption barriers for Pt(111) is shown to be useful in predicting the low coverage desorption barriers for oxygen desorption from other metal surfaces, which showed reasonable agreement with the reported experimental values for those other metals. The supporting information file is especially interesting because it has nearly all of the data files used in the paper embedded in it!

Copyright (C) 2013 by John Kitchin. See the License for information about copying.

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