Electrochemical electrode-electrolyte interfaces studied from first principles

In spite of its technological relevance in the energy conversion and storage, our knowledge about the microscopic structure of electrochemical electrode-electrolyte interfaces and electrical double layers is still rather limited. The description of these interfaces from first principles is hampered by three facts. i) In electrochemistry, structures and properties of the electrode-electrolyte interfaces are governed by the electrode potential which adds considerable complexity to the theoretical treatment since charged surfaces have to be considered. ii) The theoretical treatment of processes at solid-liquid interfaces includes a proper description of the liquid which requires to determine free energies instead of just total energies. This means that computationally expensive statistical averages have to be performed. iii) Electronic structure methods based on density functional theory (DFT) combine numerical efficiency with a satisfactory accuracy. However, there are severe shortcomings of the DFT description of liquids, in particular water, using current functionals.Despite these obstacles, there has already significant progress been made in the first-principles modeling of electrochemical electrode-electrolyte interfaces. In this contribution, I will present our attempts [1-7] to contribute to this progress by systematically increasing the complexity of the considered systems. Thus we have addressed thermal disorder by performing ab initio molecular dynamics simulations [1], the DFT water description has been improved by including dispersion effects [2], varying electrode potentials have been considered in a numerical setup with an explicit counter electrode [3], water structures at stepped electrodes have been studied [4], and the fact that in equilibrium electrodes are typically covered by adsorbates has been taken into account [5, 6]. Furthermore, first attempts to include a realistic description of the anion adsorption on electrode-electrolyte interfaces [7] will be discussed.References

1. Schnur, S. and Gross, A. New J. Phys. 2009, 11, 125003.
2. Tonigold, K. and Gross, A., J. Comput. Chem. 2012, 33, 695.
3. Schnur, S. and Gross, A. Catal. Today 2011, 165, 129.
4. Lin, X. and A. Gross, A., Surf. Sci. 2012, 606, 886.
5. Roman, T. and Gross, A., Catal. Today 2013, 202, 1838.
6. Gross, A., Gossenberger, F., Lin, X., Naderian, M., Sakong, S., Roman, T., J. Electrochem. Soc. 2013, 161, E3015.
7. Roman, T. and Gross, A., Phys. Rev. Lett. 2013, 110,156804.