ZnO is a wide band gap semiconductor which is of interest to such diverse areas of application as passivation layers on steel surfaces, catalysis, corrosion, adhesion, gas sensing, and micro- or optoelectronics. Understanding the surface structure and stoichiometry is of high practical interest and essential for any of the mentioned applications. Keeping in mind that the chemical environment interfacing with the surface plays a decisive role in the stabilisation and atomic structure of the surface reconstruction, we combine density functional theory (DFT) calculations with atomistic thermodynamics to investigate and understand the stability of polar Zn-terminated ZnO(0001) surfaces in dry and humid environment.
Combining concepts of semiconductor physics and corrosion science, we develop a novel approach that allows us to perform ab initio calculations under controlled potentiostat conditions for electrochemical systems. The proposed approach can be straightforwardly applied in standard density functional theory codes.
Solid-liquid interfaces are at the heart of many problems of practical importance, such as water electrolysis and batteries, photo catalytic water splitting, electro-catalysis, or corrosion. Understanding the structures forming at surfaces of solids immersed in an aqueous electrolyte is, therefore, of particularly high interest. In this project, we investigate the role the liquid environment plays in shaping such structures. We show that solvation effects are highly selective, having little effect on surfaces with metallic character, but largely stabilizing semiconducting structures, particularly those that experience a high electrostatic penalty in vacuum.
We apply our novel potentiostat approach to study the chemical reactions that take place during initial corrosion at the water-Mg interface under anodic polarization. Based on the gained insight, we derive an atomistic model that explains the origin of the anodic hydrogen evolution.