New materials with properties tailored to specific applications often represent the heart of novel chemical processes and important technological advances. The fundamental understanding of the correlation between materials structure and properties is the key to designing new materials with the desired properties. The primary focus of our research is on the atomic-scale materials design, based on first-principles electronic structure calculations. We are applying state-of-the-art theoretical methods to study a range of important surface phenomena including adsorption, diffusion and chemical reactions on a variety of thermal catalytic, electrocatalytic, and semiconductor surfaces.
These quantum chemical and solid-state physics methods take advantage of the impressive computational speed provided by modern supercomputers. Recent progress in theory allows for approximate solutions to the exact electronic structure problem to be obtained with reasonable accuracy, compared to experimental data. As a result, we can now calculate good estimates for binding energies and diffusion barriers of atoms and molecules on, for example, transition metal surfaces. Moreover, site preferences, adsorbate interactions, nature of specific bonds can all be investigated thoroughly and complement the information provided by advanced experimental techniques. Sophisticated computational algorithms are implemented for the determination of the detailed reaction paths connecting reactants and products of elementary reaction steps of important reaction schemes.
In the course of revealing all this information at the atomic and molecular level, important reaction intermediates, often spectroscopically elusive, can be discovered, thus guiding new experimental efforts towards unexplored territory. The detailed study of competing reaction paths, through the calculation of the corresponding activation energy barriers, allows for the isolation of electronic and geometric factors determining reaction selectivity in a way that is not accessible to experiments, where usually a set of overlapping factors act simultaneously.
Energetics from quantum mechanics is used in mean-field and stochastic microkinetic models that allow for direct comparison with experimentally determined quantities such as reactions rates, activation energy and reactions orders. Such a comparison allows for the iterative determination of the nature of the active site as a function of reaction conditions.
Our general research strategy is to study trends in chemical reactivity of solid surfaces and identify discontinuities in their behavior. Explaining trends and discontinuities can help us understand the fundamental reasons behind changes in reactivity. We can then proceed, in strong interaction with experiments, to design surfaces characterized by the desired properties. Modern machine learning methods are enabling us to study relevant phenomena with characteristic length/time scales much larger than those that direct quantum mechanical methods can handle.
The major focus of our current research efforts is on the fundamental reactivity studies for a wide range of important applications, including: fuel cells electrocatalysis, bimetallic catalysis, the development of novel low temperature and environmentally benign catalytic processes, and sensors based on chemoresponsive systems.