Sonoactivated polycrystalline Ni electrodes for alkaline oxygen evolution reaction

Faranak Foroughi; Alaa Y Faid; Svein Sunde; Bruno G Pollet

doi:10.1016/j.ultsonch.2022.106013

Sonoactivated polycrystalline Ni electrodes for alkaline oxygen evolution reaction

Ultrason Sonochem. 2022 May:86:106013. doi: 10.1016/j.ultsonch.2022.106013. Epub 2022 Apr 23.

Authors

Faranak Foroughi¹, Alaa Y Faid², Svein Sunde², Bruno G Pollet³

Affiliations

¹ Hydrogen Energy and Sonochemistry Research Group, Department of Energy and Process Engineering, Faculty of Engineering, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim, Norway; Electrochemistry Research Group, Department of Materials Science and Engineering, Faculty of Natural Sciences. Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim, Norway. Electronic address: faranak.foroughi@ntnu.no.
² Electrochemistry Research Group, Department of Materials Science and Engineering, Faculty of Natural Sciences. Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim, Norway.
³ Hydrogen Energy and Sonochemistry Research Group, Department of Energy and Process Engineering, Faculty of Engineering, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim, Norway; Green Hydrogen Lab (GH2Lab), Pollet Research Group, Hydrogen Research Institute, Université du Québec à Trois-Rivières, 3351 Boulevard des Forges, Trois-Rivières, Québec G9A 5H7, Canada.

Abstract

The development of cost-effective and active water-splitting electrocatalysts is an essential step toward the realization of sustainable energy. Its success requires an intensive improvement in the kinetics of the anodic half-reaction of the oxygen evolution reaction (OER), which determines the overall system efficiency to a large extent. In this work, we designed a facile and one-route strategy to activate the surface of metallic nickel (Ni) for the OER in alkaline media by ultrasound (24 kHz, 44 W, 60% acoustic amplitude, ultrasonic horn). Sonoactivated Ni showed enhanced OER activity with a much lower potential at + 10 mA cm^-2 of + 1.594 V vs. RHE after 30 min ultrasonic treatment compared to + 1.617 V vs. RHE before ultrasonication. In addition, lower charge transfer resistance of 11.1 Ω was observed for sonoactivated Ni as compared to 98.5 Ω for non-sonoactivated Ni. In our conditions, ultrasound did not greatly affect the electrochemical surface area (A_ecsa) and Tafel slopes however, the enhancement of OER activity can be due to the formation of free OH^• radicals resulting from cavitation bubbles collapsing at the electrode/electrolyte interface.

Keywords: Alkaline; Electrolysis; Nickel; Oxygen evolution reaction; Ultrasound.