Exploring the catalytic performance of a GeTe monolayer for nonaqueous Na–O2 batteries: an in silico study†
Abstract
The non-aqueous metal–oxygen battery systems have high theoretical energy densities, making them promising alternatives for use in energy storage and electronic devices. However, despite this benefit, there are several issues—such as slow kinetics, high overpotentials and poor cycling processes—that limit the battery performance. Therefore, in the present work, we systematically investigated the dynamical and mechanical stability of a germanium telluride (GeTe) monolayer (ML) by calculating the cohesive energy (−2.16 eV per atom), and analysing AIMD simulations and phonon dispersion curves. Also, we examined the catalytic performance of the GeTe ML as a suitable cathode catalyst material in a sodium-oxygen battery. Furthermore, after demonstrating the stable adsorption geometries of NaxO2y intermediates on the ML, it is shown that the catalytic reaction follows a four-electron pathway, with Na4O2 as the final discharge product. After that, we have calculated the theoretical ORR and OER overpotentials (ηORR and ηOER) for both four-electron and two-electron pathways. In the case of the most energetic pathway (four-electron pathway), the calculated ORR and OER overpotentials (0.97 V and 0.65 V) are considerably low, which makes the GeTe ML an excellent pick as a high-performance cathode catalyst material. Additionally, we investigated the adsorption mechanism of various organic solvents on the surface of the ML; the nominal and negligible adsorption energies (−0.40 eV to 0.26 eV) of the electrolytes indicate that the GeTe ML is a potential cathode catalyst candidate.