The Second Life of Cobalt MOF: Alternating Magnetic Field‐ Assisted Electrocatalytic Oxygen Evolution Reaction in MOF‐derived Nanoparticles

A major challenge in hydrogen production from water electrolysis is the slow kinetics of oxygen evolution (OER). Applying an alternating magnetic field (AMF) to ferromagnetic metal nanoparticles on electrodes has gained attention due to the generation of a thermally activated electrocatalyst, which can boost OER performance. This work studies the influence of external parameters and intrinsic characteristics of carbon-encapsulated cobalt MOF-derived nanoparticles deposited onto graphite paper electrodes on the electrocatalytic AMF-OER coupled process. Specifically, the impact of AMF strength, the electrolyte composition (concentration and cation nature) and cobalt content on the electrocatalytic AMF-OER performance are thoroughly investigated. Results reveal that AMF significantly boosts OER activity of Co@C-based electrodes, their enhancement being strongly dependent on the electrolyte composition. Furthermore, both the heating capacity of the herein synthesized catalyst for magnetic hyperthermia and their structural features remain intact after an intense and prolonged electrocatalytic AMF-OER experiment. No signs of sintering, leaching, or particle size increase, which are typical issues observed when metal nanoparticles are subjected to an intense external magnetic field, have been found. This underscores the high operational stability of this catalyst. These findings provide new insights into thermal AMF-assisted alkaline water oxidation for developing high-performance catalysts for enhanced electrocatalysis.