Hydrogen energetics and charge transfer in the Ni/LaNbO4 interface from DFT calculations

• Published in: International journal of hydrogen energy 2012-05, Vol.37 (9), p.8033-8042
• Main Authors: Hadidi, K., Norby, T., Løvvik, O.M., Gunnæs, A.E.
• Format: Article
• Language: English
• Subjects: Alternative fuels. Production and utilization; Applied sciences; Barriers; Density functional theory; DFT; Diffusion; Energy; Exact sciences and technology; Fuel cell; Fuels; Hydrogen; Interface; LaNbO4; Mathematical analysis; Nickel; Phases; Potential energy; Simulation
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2011.11.032

Calculations based on density functional theory have been used to simulate interface structures between the tetragonal and monoclinic phases of LaNbO4 (LN) and Ni. Schottky barrier heights were calculated using the interface electronic structure; they were 3.0 and 1.8eV for p- and n-type barriers. The hydrogen interstitials were found to be significantly higher stable in the LN part of the interface than in bulk LN. Also, the potential energy curve of hydrogen diffusion from Ni into LN exhibited a deep well of around 2eV, located in the gap region between two components. The stability of H atom in the gap region and interfacial layers of LN is explained by metal-induced gap states and indicates that there will be an accumulation of hydrogen in this area. It was shown that hydrogen is ionized when enters from Ni to the LN interfacial layer, approaching to the O atoms and that the electron lost from hydrogen resides in the interface states, located in the band gap of LN. ► Calculating Schottky barrier height at the interface region. ► Analysis of electronic structure of the LaNbO4/Ni interface. ► The potential energy curve for hydrogen interstitials at the interfacial region. ► Presenting the ionization mechanism of the H atom in the interfacial region.