Ab initio study of hydrogen storage on metal-decorated GeC monolayers

• Published in: International journal of hydrogen energy Vol. 46; no. 57; pp. 29261 - 29271
• Main Authors: Arellano, Lucia Guadalupe, De Santiago, Francisco, Miranda, Álvaro, Pérez, Luis Antonio, Salazar, Fernando, Trejo, Alejandro, Nakamura, Jun, Cruz-Irisson, Miguel
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 18-08-2021
• Subjects: 2D materials; Alkali metals; DFT; Germanium carbide; Hydrogen storage; Renewable energy; Hydrogen storage; DFT; Renewable energy; Germanium carbide; Alkali metals; 2D materials
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2021.04.135

Bidimensional nanostructures have been proposed as hydrogen-storage systems owing to their large surface-to-volume ratios. Germanium carbide monolayers (GeC-MLs) can offer attractive opportunities for H2 adsorption compared to graphene. However, this possibility has not been explored in detail. In this work, the adsorption of H2 molecules on GeC-MLs decorated with alkali metal (AM) and alkaline earth metal (AEM) adatoms was investigated using the density functional theory. Results showed that the AM adatoms were chemisorbed on the GeC-ML, whereas AEM adatoms were physisorbed. The H2 molecules presented negligible adsorption energies on the weakly adsorbed AEM adatoms. Conversely, the AM adatoms improved the H2 adsorption, possibly due to a large charge transfer from the adatoms to the GeC-ML. The potassium-decorated GeC-ML exhibited the most optimal H2 storage capacity, adsorbing up to six molecules and with a lower possibility of forming metal clusters than the other studied cases. These results may aid in the development of new efficient hydrogen-storage materials.
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•GeC monolayers were decorated with alkali and alkaline earth metal adatoms.•Strong alkali metal—monolayer bond yields optimal H2 adsorption energies.•Weak alkaline earth metal—monolayer bond yields negligible H2 adsorption energies.•Li, Na and K adatoms can adsorb 3, 6 and 6H2 molecules, respectively.•K-decorated GeC monolayers have unlikely adatom clusterization.