Furthermore, even when an ion exchange membrane (Nafion) is used, Pt dissolution and deposition on the working electrode still takes place 8. Then, the dissolved Pt ions redeposit on the surface of the working electrode, resulting in deceptive enhancement in the measured overpotential 4, 6, 7. However, Pt is not stable and undergoes chemical/electrochemical dissolution during potential cycling 4, 6, 7. Nevertheless, almost half of the published studies related to HER used Pt as the counter electrode with no ion-exchange membrane used 4, 5. Also, Ni − C-based catalysts showed comparable performance to that of Pt in HER 3. For instance, previous studies introduced molybdenum carbide combined with rGO, revealing almost the same activity towards hydrogen evolution reaction (HER) of Pt/C 2.
Therefore, there is a growing need to develop earth-abundant hydrogen evolution reaction electrocatalysts that possess comparable catalytic activity to that of Pt while being inexpensive. However, its use in large scale production has been greatly restricted due to its high cost. In this system, Pt is the most widely used electrocatalyst for the water reduction half reaction due to its efficient electrical conductivity, high mechanical strength, and superior catalytic activity 1. In this regard, electrolysis is the commonly used process to produce hydrogen in large quantities. Finally, commercial Ti mesh is demonstrated as an alternative emerging counter electrode, which is proven to be very stable and convenient to study the HER in acidic media.ĭuring the past few decades, hydrogen has been introduced as a promising alternative to traditional fossil fuels. Specifically, the correlation between the working electrode area to that of the counter electrode, the dissolution rate of the counter electrode, and the potential range used in the activation/cleaning of the surface on accelerating the dissolution rate is explored and discussed in detail. Herein, while we systematically unveil such problems, an alternative counter electrode that overcomes those problems is demonstrated. This issue becomes more critical when the electrolysis measurements involve an activation step, necessitating the need for alternative counter electrodes that are stable, especially in acidic medium, which is commonly used as the electrolyte in HER studies. Consequently, this has been frequently confused with the actual electrochemical signature of the working electrode catalyst, resulting in a deceptive enhancement in the recorded overpotential. However, the extensive application of such electrodes has raised caveats on the contribution of the redox-active species dissolving from such electrodes and redepositing on the surface of the working electrode to the measured overpotential. In this system, several counter electrodes are commonly used to ensure fast kinetics, including Pt, gold, and glassy carbon.
Electrochemical hydrogen evolution reaction (HER) is typically studied in three-electrode system.
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