The Power of Computing for Chemistry Fundamentals in New Energy Technologies

Dr. Michel Dupuis

Physical Sciences Division, Pacific Northwest National Laboratory, Richland (WA)

Modern capabilities in computations and simulations in multi-scale approaches allow us to address successfully many of the complex chemistry and physics fundamentals of sun-to-fuel and electricity-to-fuel energy conversions. In this presentation we will describe recent studies relevant to these new energy technologies, highlight successes, and underscore remaining and future challenges.

In the context of photo conversions, characterization of electron/hole separation, recombination, and transport is essential to design of efficient devices. We successfully characterized the e/h transport properties of TiO₂ and other oxides using density functional theory DFT combined with Marcus/Holstein theory. Our calculations led us also to formulate a universal role of excess electrons on the surface chemistry of oxides. In the context of proton membranes for fuel cells, understanding the factors affecting proton transport in polymeric and ionic liquid membranes is essential toward designing efficient low cost stable membranes. Ab initio and classical molecular dynamics MD combined with percolation theory provided a means to characterize successfully pore structure and proton transport properties. Water percolation is a powerful descriptor characterizing efficient proton transport. Most recently, our focus has been on molecular electro-catalysis. DFT-based quantum QM and mixed QM/MM approaches coupled with accelerated phase space sampling techniques for free energy calculation, and micro-kinetic modeling have led to accurate calculations of the catalytic performance of novel proton relay-based molecular catalysts for H₂ oxidation and evolution. These efforts have reached what is perhaps an unprecedented level of success that put us within grasp of design by computer.

These studies underscore the power of computations and the impact of high performance computing in characterizing the fundamental chemistry in complex molecular and solid state environments. Successes and challenges point to the key role of high-performance computing and the essential need for further advances in methods for multi-scale modeling.

Acknowledgements: This research was supported in part by the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES) and in part by DOE/BES Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory is operated for the U.S. Department of Energy by Battelle.