Energy band alignment and electronic states of amorphous carbon surfaces in vacuo and in aqueous environment

Journal Article · Wed Jan 21 04:00:00 EST 2015 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4905915· OSTI ID:22412964

Määttä, Jukka ^[1]; Lopez-Acevedo, Olga ^[2]; Laurila, Tomi ^[3]

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1. Department of Chemistry, Aalto University, Espoo (Finland)
2. Department of Applied Physics, COMP Centre of Excellence in Computational Nanoscience, Aalto University, Espoo (Finland)
3. Department of Electrical Engineering and Automation, Aalto University, Espoo (Finland)

In this paper, we obtain the energy band positions of amorphous carbon (a–C) surfaces in vacuum and in aqueous environment. The calculations are performed using a combination of (i) classical molecular dynamics (MD), (ii) Kohn-Sham density functional theory with the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional, and (iii) the screened-exchange hybrid functional of Heyd, Scuseria, and Ernzerhof (HSE). PBE allows an accurate generation of a-C and the evaluation of the local electrostatic potential in the a-C/water system, HSE yields an improved description of energetic positions which is critical in this case, and classical MD enables a computationally affordable description of water. Our explicit calculation shows that, both in vacuo and in aqueous environment, the a-C electronic states available in the region comprised between the H{sub 2}/H{sub 2}O and O{sub 2}/H{sub 2}O levels of water correspond to both occupied and unoccupied states within the a-C pseudogap region. These are localized states associated to sp{sup 2} sites in a-C. The band realignment induces a shift of approximately 300 meV of the a-C energy band positions with respect to the redox levels of water.

• OSTI ID: 22412964
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 3 Vol. 117; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
AMORPHOUS STATE
APPROXIMATIONS
CARBON
DENSITY FUNCTIONAL METHOD
ELECTRONIC STRUCTURE
ENERGY GAP
HYDROGEN
MOLECULAR DYNAMICS METHOD
POTENTIALS
SURFACES
WATER