Abstract
The hydrogen electrode reaction (HER) on Pt electrode in a H2SO4 solution when CO gas was injected/stopped was studied using polarization resistance curve. In order to elucidate and confirm the CO poisoning effect, a few curve techniques were proposed. Applying them, the kinetic parameters such as the number of electrons transferred (z) and the cathodic transfer coefficient (αc) were determined. The HER in a 0.5 mol dm−3 H2SO4 solution saturated with H2 was confirmed as a reversible reaction having z = 2. When the above solution was injected with CO, the reversible HER changed to an irreversible reaction having z = 1 and αc ≈ 0.6. Once we stopped the CO injection, alteration from the irreversible to quasireversible reaction was gradually made after several cyclic polarizations. The proposed curve techniques can provide a reliable way to determine the kinetic parameters changing among reversible, irreversible, and quasireversible reactions.
Highlights
The hydrogen electrode reaction (HER) is one of the most fundamental electrolytic reactions in the field of electrochemistry [1,2,3,4,5,6,7,8,9,10]
To detect a variation of the open circuit potential, Eocp(t), the experiments were simulated in three environments: Environment (I): 0.5 mol dm-3 H2SO4 solution saturated with H2 only; Environment (II): the above H2SO4 solution injected with continuous CO bubbling; Environment (III): the above H2SO4 solution when the CO-injection was stopped
In order to analyze the CO poisoning effect, a few curve techniques were employed to investigate the hydrogen electrode reaction (HER = hor + her) occurring on the Pt electrode in a 0.5 mol dm-3 H2SO4 solution saturated with H2 when CO-injected or not
Summary
The hydrogen electrode reaction (HER) is one of the most fundamental electrolytic reactions in the field of electrochemistry [1,2,3,4,5,6,7,8,9,10]. Many papers reported that even a small amount of CO can poison the platinum catalyst and reduce its efficiency [11]. This poisoning phenomenon is said to be mainly caused by the firm adhesion of CO as COad to the platinum electrode surface. It is necessary to explain the degradation of the electrode from the surface inactivation caused by CO adsorption and from the physical factors derived from it
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