Dresden 2017 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 89: Oxide and Insulator Surfaces: Adsorption III

O 89.9: Vortrag

Donnerstag, 23. März 2017, 12:30–12:45, TRE Phy

Improving the photoelectrochemical performance of cobalt ferrite by transition metal substitution: A DFT+U study — •Hamidreza Hajiyani and Rossitza Pentcheva — Fakultät für Physik and Center of Nanointegration (CENIDE), Universität Duisburg-Essen, 47057 Duisburg

Transition metal oxides are considered as promising materials for photo-anodes to convert solar energy into hydrogen fuel through water oxidation. Here we report density functional theory+U (DFT+U) calculations on the influence of transition metal mixing on the performance of cobalt ferrite (CoFe₂O₄) as anode material in the oxygen evolution reaction (OER). Our results on M_xCo_1−xFe₂O₄ (111) surfaces illustrate that the overpotential during OER process can be reduced by partial substitution of Co sites with elements such as Ni. We find that this improvement is related to modification of the binding energy of the reaction intermediates during water oxidation. Analysis of spin density and electronic properties shows that substitution of nickel in cobalt ferrite varies the band gap, band edge positions and oxidation state of cations at the (111) surface.

We acknowledge support by the DFG within priority program SPP1613, project PE883/9-2 and the computational time at the Leibnitz Rechenzentrum (grant pr87ro) and at magnitUDE.