Hydrogen, among of the other forms considered so far, is suitable medium for large scale energy storage for long duration and can be transported in large quantity using, for example, a gas pipeline or cryocompressed liquid hydrogen tanker, crucial factors for further deployment of renewable energies and electrification of automobiles since such energy sources are intermittent in nature and its geographical distribution is uneven [1,2,3]. Photoelectrochemical hydrogen production device produces hydrogen from water using sunlight as a single device making it an attractive option, however, complexity of electrochemical processes such as, for example, seeming correlation between hydrogen evolution reaction, oxygen evolution reaction, and corrosion, complicates development of an effective device optimization strategy due to difficulty in understanding the origin of performance and durability issues.

In this talk, we will discuss about our efforts in developing computational capabilities for accelerating water splitting materials development and their optimization via (1) assisting interpretation of in-situ experimental characterization and (2) assisting novel materials synthesis and optimization by providing comprehensive materials property information based on ab-initio DFT simulations [4,5,6]. For (1), we will show how ab-initio XPS and band alignment simulations could be used to gain atomistic insight about the chemical composition of electrochemical interfaces, which was very challenging until very recently if not impossible. For (2), we will show how one can screen quickly good candidate materials for photoelectrode, identify possible synthesis pathway, diagnose issues in the synthesized materials based on ab-initio simulations. An important commonality in these two use cases is that ab-initio simulation can connect multiple properties (stability, transport, spectroscopic) with the same level of reliability so that one can make a robust judgement by examining overall consistency over multiple factors (properties) between theory and experiments.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344, and is supported by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Fuel Cell Technologies Office via HydroGEN consortium and H2@Scale.

1. https://www.nrel.gov/gis/solar.html
2. https://windexchange.energy.gov/maps-data
3. “Implications of diurnal and seasonal variations in renewable energy generation for large scale energy storage”, F. M. Mulder, J. Renewable Sustainable Energy 6, 033105 (2014).
4. “Methods for Photoelectrode Characterization with High Spatial and Temporal Resolution”, D. Esposito, J. Baxter, J. John, N. Lewis, T. Moffat, T. Ogitsu, G. O'Neil, T. Pham, A. Alec, J. Velazquez, B. Wood, Energy & Environmental Science 8, 2863 (2015).
5. “Integrating Ab Initio Simulations and X-ray Photoelectron Spectroscopy: Toward A Realistic Description of Oxidized Solid/Liquid Interfaces”, J. Phys. Chem. Lett. 9, 194 (2018).
6. “Assessing the role of hydrogen in Fermi-level pinning in chalcopyrite and kesterite solar absorbers from first-principles calculations”, J. Varley, V. Lordi, T Ogitsu, A. DeAngelis, K. Horsley, N. Gaillard, J. Appl. Phys. 123, 161408 (2018).