Regensburg 2019 – wissenschaftliches Programm
O 66.8: Poster
Mittwoch, 3. April 2019, 17:45–20:00, Poster B2
Hematene for the oxygen evolution reaction — •Yidan Wei, Mahdi Ghorbani-Asl, and Arkady Krasheninnikov — Institute of Ion Beam Physics and Materials Research, Helmholtz Zentrum Dresden Rossendorf, Dresden 01328, Germany
Using density functional theory (DFT) calculations, the catalytic activity of a recent member of two-dimensional (2D) materials, hematene (α-Fe2O3 monolayer), has been studied for oxygen evolution reactions (OER). The stability and electronic structure of two experimentally faceted sheets of hematene, (001) and (010), was investigated. It was found that the (001) facet (1.589 eV) exhibits lower cleaving energy in comparison to the (010) facet (1.892 eV) suggesting a more stable structure. The electronic structure calculations indicate that facets of hematene for (001) and (010) are semiconducting monolayer with a large energy gap of about 1.51 eV and 1.36 eV in comparison to its bulk counterpart (1.8-2.2 eV). We also studied the relationship between the experimentally observed facets and their OER catalytic reactivity. It is found that the determining step in the OER process is the reaction of a H2O molecule in the surface to form an adsorbed hydroxyl group (O*). The variation of Gibbs energy is around 0.4 eV at most. The (010) facet showed a lower barrier for oxygen evolution than (001) facet. It was also demonstrated that the adsorption free energy and onset overpotential can be further tuned by defects, such as vacancies.