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Center for Nonlinear Studies |
Electrochemical processes are at the heart of many present day technological challenges.Examples are the improvement of battery materials, electro-catalysis, fuel cells, corrosion andothers. A prerequisite to optimising a desired functionality or suppressing an undesiredproperty is the identification of relevant mechanisms at the microscale and understanding howthey influence properties at the macroscale.
Density functional theory (DFT) calculations are able to resolve processes at the microscopicscale and have proven immensely successful in providing insight in various areas of materialsscience, complementing experimental information. However, the presence of different classesof materials with dissimilar characteristics (metal, semiconductor/insulator, liquid) withinelectrochemical systems is particularly challenging for the DFT modelling, as they imposedifferent requirements on the investigational approaches.
The presentation will show how by adapting concepts originally developed in the field ofsemiconductor physics [1] we were able to successfully tackle questions related toelectrochemical processes. One example is ZnO in aqueous environment. Constructing a defectphase diagram for this system enabled us to assess the impact an electrochemical environmenthas on the electronic structure of a semiconducting electrode [2]. By identifying the relevantbulk point defects of this material, we assessed their impact on the properties and stability ofthe solid, suggesting routes to counteract corrosion [3]. Surface Pourbaix diagrams for theZnO(0001)/H2O system, on the other hand, revealed the role the solvent plays in shaping andstabilizing surface reconstructions [4]. Finally, I will discuss our novel potentiostat design,which enables us to perform ab initio calculations under controlled bias conditions. Itsapplication to Mg allowed us to solve a 150-year-old problem, which links H-evolution underanodic conditions to Mg dissolution [5].
[1] M. Todorova and J. Neugebauer, Phys. Rev. Appl. 1 (2014) 014001.[2] M. Todorova and J. Neugebauer, Surf. Sci. 631 (2015) 190-195.[3] M. Todorova and J. Neugebauer, Farad. Discussions 180 (2015) 97-112.[4] S. Yoo, M. Todorova and J. Neugebauer, Phys. Rev. Lett. 120, 066101 (2018).[5] S. Surendralal, M. Todorova, M. Finnis and J. Neugebauer, Phys. Rev. Lett. 120, 246801(2018).
Host: Ping Yang/Enrique Batista