An alternative, low-dissolution counter electrode to prevent deceptive enhancement of HER overpotential

Abstract

Electrochemical hydrogen evolution reaction (HER) is typically studied in three-electrode system. In this system, several counter electrodes are commonly used to ensure fast kinetics, including Pt, gold, and glassy carbon. 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. 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. 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. Herein, while we systematically unveil such problems, an alternative counter electrode that overcomes those problems is demonstrated. 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. 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.

Highly Durable Compositionally Variant Bifunctional Tetrametallic Ni–Co–Mn–Fe Phosphide Electrocatalysts Synthesized by a Facile Electrodeposition Method for High-Performance Overall Water Splitting

“…44 More importantly, Ti mesh showed very low activity toward water electrolysis. 4 Inspired by the previously mentioned studies, herein, different composites of Ni, Fe, Co, and Mn have been electrodeposited on Ti mesh substrates with and without phosphidation. The electrocatalytic activity of the fabricated composites toward OER and HER in alkaline electrolyte (1 M KOH) was studied.…”

“…To this end, Ti mesh, as a low cost material ($.23/inch), was proven to be a suitable substrate due to its large-surface area, high stability in different pH values, and high corrosion resistance . More importantly, Ti mesh showed very low activity toward water electrolysis …”

“…Nevertheless, the high cost and scarcity of those elements are very challenging, impeding the use of such catalysts in large-scale industrial applications. In addition, their lack of stability in alkaline and acidic media limits their use over a wide pH range. − …”

C76 Nanospheres/Ni Foam as High-Performance Heterostructured Electrocatalysts for Hydrogen Evolution Reaction: Unveiling the Interfacial Interaction

“…Although noble metals are the benchmark catalysts for the hydrogen evolution reaction (HER), they suffer from the high cost, limited stability, and selectivity . Hence, there is an increasing demand to identify alternative inexpensive catalysts that offer comparable catalytic activity to the noble metals along with high stability and durability . To this end, low-dimensional nanomaterials have been explored as alternatives, ,, where the interfacial interactions can be used to optimize the electronic structure and activity of those nanostructures. , Although nickel is a promising electrocatalyst compared to other transition metals, especially Ni foam that has large surface area, the overpotential needed to drive the HER using Ni foam as an electrocatalyst is still relatively high compared to the benchmark catalysts. − Moreover, interface engineering with low dimensional nanostructures seems to be very promising in introducing new electrocatalytic systems with comparable activity to the noble metals.…”

“…1 Hence, there is an increasing demand to identify alternative inexpensive catalysts that offer comparable catalytic activity to the noble metals along with high stability and durability. 2 To this end, lowdimensional nanomaterials have been explored as alternatives, 1,3,4 where the interfacial interactions can be used to optimize the electronic structure and activity of those nanostructures. 5,6 Although nickel is a promising electrocatalyst compared to other transition metals, especially Ni foam that has large surface area, the overpotential needed to drive the HER using Ni foam as an electrocatalyst is still relatively high compared to the benchmark catalysts.…”