Electrochemical View of the Band Gap of Liquid Water for Any Solution

Alexander Shimkevich

NRC Kurchatov Institute, Moscow, Russia.

DOI: 10.4236/wjcmp.2014.44027                

Abstract

Studying liquid water in a frame of band theory shows that varying a reduction-oxidation (RedOx) potential of aqueous solution can be identified as shifting Fermi level in its band gap. This medium becomes the reductive one when Fermi level is shifting to the conduction band due to populating hydroxonium level (H₃O⁺/ H₃O) by electrons and transforming water in a hypo-stoichiometric state, H₂O_1-│X│. Opposite in the hyper-stoichiometric one H₂O_1+│X│ Fermi level is shifting to the valence band due to populating hydroxide level OH/OH^- by holes and the aqueous solution becomes the oxidative one. The energy difference between these electronic levels is estimated of 1.75 eV. It is shown that the standard half-reactions and the typical aqueous electrodes fix their RedOx potential only by the electrons and holes populations ([H₃O],[OH]) of these local electronic levels in the band gap of non-stoichiometric water in the corresponding solutions.

Keywords

Liquid Water, Band Gap, Fermi Level, Hydroxonium Ion, Hydroxide Ion

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Garbuio, V., Cascella, M. and Pulci, O. (2009) Excited State Properties of Liquid Water. Journal of Physics: Condensed Matter, 21, 1-15. http://dx.doi.org/10.1088/0953-8984/21/3/033101
[2]	Do Couto, P.C., Guedes, R.C. and Costa Cabral, B.J. (2004) The Density of States and Band Gap of Liquid Water by Sequential Monte-Carlo and Quantum Mechanics Calculations. Brazilian Journal of Physics, 34, 42-47. http://dx.doi.org/10.1590/S0103-97332004000100007
[3]	Hehre, W.J., Radom, L., Schleyer, P.V.R. and Pople, J.A. (1986) Ab Initio Molecular Orbital Theory. John Wiley & sons Ltd., New York.
[4]	Abu-Awwad, F. and Politzer, P. (2000) Variation of Parameters in Becke-3 Hybrid Exchange-Correlation Functional. Journal of Computational Chemistry, 21, 227-238. http://dx.doi.org/10.1002/(SICI)1096-987X(200002)21:3<227::AID-JCC6>3.0.CO;2-A
[5]	Laasonen, K., Sprik, M., Parrinello, M. and Car, R. (1993) “Ab Initio” Liquid Water. The Journal of Chemical Physics, 99, 9080-9089. http://dx.doi.org/10.1063/1.465574
[6]	Bernas, A., Ferradini, C. and Jay-Gerin, J.P. (1997) On the Electronic Structure of Liquid Water: Facts and Reflections. Chemical Physics, 222, 151-160. http://dx.doi.org/10.1016/S0301-0104(97)00213-9
[7]	Coe, J.V., Earhart, A.D., Cohen, M.C., Hoffman, G.J., Sarkas, H.W. and Bowen, K.H. (1997) Using Cluster Studies to Approach the Electronic Structure of Bulk Water: Reassessing the Vacuum Level, Conduction Band Edge and Band Gap of Water. The Journal of Chemical Physics, 107, 6023-6031. http://dx.doi.org/10.1063/1.474271
[8]	Do Couto, P.C. (2007) Understanding Electronic Properties of Water: A Theoretical Approach to the Calculation of the Adiabatic Band Gap of Liquid Water. Ph.D. Thesis, Lisbon University, Lisbon.
[9]	Winter, B., Weber, R., Widdra, W., Dittmar, M., Faubel and Hertel, I.V. (2004) Full Valence Band Photoemission from Liquid Water Using EUV Synchrotron Radiation. The Journal of Physical Chemistry A, 108, 2625-2632. http://dx.doi.org/10.1021/jp030263q
[10]	Kittel, Ch. and Kroemer, H. (1980) Thermal Physics. W. H. Freeman, San Francisco.
[11]	Kittel, Ch. (2004) Introduction to Solid State Physics. 8th Edition, Wiley, New York.
[12]	Bard, A.J., Parsons, R. and Jordan, J. (1985) Standard Potentials in Aqueous Solutions. Marcel Dekker, New York.
[13]	Kikoin, I.K., Ed. (1976) Tables of Physical Constants, Handbook. AtomIzdat, Moscow.
[14]	Shimkevich, A.L. and Shimkevich, I.Yu. (2012) On 2D Water Chemistry. Proceedings of the International Conference on Nuclear Plant Chemistry, Paris, 23-28 September 2004, 139-176.
[15]	Shimkevich, A.L. (2013) On Arising Nanohydrides in Reduced Alkaline Solution. American Journal of Modern Physics, 2, 185-189. http://dx.doi.org/10.11648/j.ajmp.20130204.11
[16]	Bandura, A.V. and Lvov, S.N. (2006) The Ionization Constant of Water over Wide Ranges of Temperature and Density. Journal of Physical and Chemical Reference Data, 35, 15-30. http://dx.doi.org/10.1063/1.1928231