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Sensors 2006, 6(10), 1187-1198;

A New Overpotential — Capacitance Mechanism for H2 Electrode

Department of Physics, University of Missouri-Kansas City, Kansas City, MO 64110, USA
Glenn Wei, Weiss Research, Inc., 13211 Stafford Road, Suite 600, Missouri City, , TX 77489, USA
Author to whom correspondence should be addressed.
Received: 22 July 2006 / Accepted: 28 September 2006 / Published: 1 October 2006
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The H2 electrode is commonly assumed to be a half-cell, 2 H+ 2e == H2, andexplained by the Nernst equation. We cannot assume that the H+ is easily reduced to H2 inan H2 saturated solution, and H2 becoming oxidized to H+ in a strongly acid solution againstthe equilibrium principle. How can the H2 gas is involved from a basic solution where thereis practically no H+ ions? Another equilibrium has been postulated, H2 (soln) = 2H(adsorbed on metal) = 2 H 2e. This paper reports the results of studying the H2 electrodeusing various techniques, such as adsorption, bubbling with H2, and N2, charging,discharging, and recharging, replacing the salt bridge with a conducting wire, etc. Aninteresting overpotential was observed that bubbling H2 into the solution caused a suddenchange of potential to more negative without changing the solution pH. The H2 may bereplaced by N2 to give a similar calibration curve without the overpotential. The resultscontradict the redox mechanism. When the Pt is separated by H2 coating, it cannot act as acatalyst in the solution. Our results seem to explain the H2 electrode mechanism as thecombination of its overpotential and capacitance potential. Bubbling of H2 or N2 onlyremoves interfering gases such as O2 and CO2. Since neither H2 nor N2 is involved in thepotential development, it is improper to call the H2 or N2 electrode. A term of pH / OH Ptelectrode, like the pH / OH glass electrode, is suggested. View Full-Text
Keywords: capacitor; overpotential; redox; interface; adsorption; N2. capacitor; overpotential; redox; interface; adsorption; N2.
This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).

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MDPI and ACS Style

Cheng, K.L.; Ashraf, N.; Wei, G. A New Overpotential — Capacitance Mechanism for H2 Electrode. Sensors 2006, 6, 1187-1198.

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