UNEXPECTED PRESENCE OF SOLUTE-FREE ZONES AT METAL-WATER INTERFACES

Authors

  • B. Chai Department of Bioengineering, Box 355061, University of Washington, Seattle, WA 98195
  • A. G. Mahtani Department of Bioengineering, Box 355061, University of Washington, Seattle, WA 98195
  • G. H. Pollack Department of Bioengineering, Box 355061, University of Washington, Seattle, WA 98195

DOI:

https://doi.org/10.7251/116

Abstract

Solute–free zones, termed “exclusion zones” are routinely seen next to hydrophilic surfaces in aqueous solution. Here we report similar zones next to various metals. The largest, approximately 200 µm in width, was found adjacent to zinc. Other reactive metals, including aluminum, tin, lead, and tungsten exhibited distinct but smaller exclusion zones, while precious metals such as platinum and gold did not produce any. Electrical potential measurements showed positive potentials within the exclusion zones, while pH measurements revealed an abundance of OH- groups in the aqueous regions beyond the exclusion zones. A correspondence was found between exclusion-zone size and the respective metal’s position within the galvanic series. The presence of these interfacial exclusion zones is unexpected, and may shed new light on electrochemical processes taking place at metal interfaces.

References

[1] P. J. Feibelman, Partial Dissociation of Water on Ru(0001), Science 295 (2002) 99−102.

[2] D. Menzel, Water on a Metal Surface, Science 295 (2002) 58−59.

[3] R. Ludwig, Water Adsorption and Structure: How Does Water Bind to Metal Surfaces: Hydrogen Atoms Up or Hydrogen Atoms Down. Angew. Chem. Int. Ed. 42 (2003) 3458-3460.

[4] P. A. Thiel, T. E. Madey, The interaction of water with solid surfaces: Fundamental aspects, Surf. Sci. Rep. 7 (1987) 211-385.

[5] M. A. Henderson, The interaction of water with solid surfaces: fundamental aspects revisited, Surf. Sci. Rep. 46 (2002) 1-308.

[6] S. Schnur and A. Gross, Properties of metal–water interfaces studied from first principles, New J. Phys. 11 (2009) 125003.

[7] Y. Gohda, S. Schnur, A. Gross, Influence of water on elementary reaction steps in electrocatalysis, Faraday Discuss. 140 (2008) 233.

[8] J. M. Zheng, G. H. Pollack, Long-range forces extending from polymer-gel surfaces, Phys. Rev. E 68 (2003) 031408

[9] J. M. Zheng, W. C. Chin, E. Khijniak, G. H. Pollack, Surfaces and interfacial water: Evidence that hydrophilic surfaces have long-range impact, Adv. Colloid Int Sci. 127 (2006) 19-27

[10] J. M. Zheng, G. H. Pollack, Water and the Cell: Solute exclusion and potential distribution near hydrophilic surfaces; Springer: Netherlands, 2006 , 165-174.

[11] J. M. Zheng, A. Wexler and G. H. Pollack, Effect of buffers on aqueous solute-exclusion zones around ion-exchange resins, J Colloid Interface Sci. 332 (2009) 511-514.

[12] B. H. Chai and G. H. Pollack, Solute-free interfacial zones in polar liquids, J. Phys. Chem. B, 114, 16,( 2010) 5371-5375.

[13] G. H. Pollack, J. Clegg, Phase Transitions in Cell Biology: Unexpected linkage between unstirred layers, exclusion zone, and water; Springer: New York, 2008, 143-152.

[14] B. H. Chai, Y. Hyok and G. H. Pollack, Spectroscopic studies of solutes in aqueous solution, J. Phys. Chem. A, 112 (2008) 2242-2247.

[15] B. H. Chai, J. M. Zheng, Q. Zhao and G. H. Pollack, Effect of radiant energy on near-surface water. J. Phys. Chem. B, 113-42 (2009) 13953-13958.

[16] V. S. Bagotsky, Fundamentals of Electrochemistry; John Wiley & Sons, Inc, 2006, 379-381.

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Published

2012-10-19