Section: Theory & Computation

Computation & Simulation

Extensive combinatorial results and ongoing basic research at the Cornell Energy Materials Center hold great promise for finding a new generation of fuel cell electrocatalysts. This research has also generated a growing library of results which is an excellent resource for making and verifying predictions about electrocatalysis. Of particular interest are the ordered intermetallic compounds PtBi and PtPb, which exhibit significantly higher activity for oxidation of some potential fuels than Pt. At the same time, developments in computational methods, especially the advent of density functional theory (DFT), have dramatically increased the predicative power of electronic structure analysis in electrocatalysis. Integration of computational and experimental results can accelerate the process of electrocatalyst discovery while improving the fundamental understanding of catalysis. Furthermore, intermetallic electrocatalysts are ideal materials for computational study because they are inherently ordered, diminishing the complexity of model development associated with alloys.

Fig 1. Typical Crystal Structure of Platinum Alloys and Ordered Intermetallics. (a) Alloy. Specific geometry positions, randomly occupied according to composition. (b) Intermetallic. Specific geometric positions also have a specific composition.

Fig 2. Formic Acid Adsorbed on Pt(111) SurfaceOn-going research uses density-functional theory to probe the influence of surface termination and chemical environment on the electronic structure of well-defined electrocatalyst surfaces, including Pt(111), irreversibly adsorbed Bi on Pt(111), and PtBi(001). Although numerous researchers have correlated the electronic structure of bulk catalysts with electrocatalytic activity, detailed studies of more realistic chemical environments can account for all-important chemical interactions between adsorbates, fuel molecules, and the catalyst surface.

Fig 3. Joint Density Functional Theory Model of Chloride Adsorbed on Chromium OxideResearchers in the Energy Materials Center are also on the forefront of developing joint density functional theory, a first-principles method of probing solvation effects that promises to revolutionize ab-initio calculations of electrochemical environments.