Magnetoelectrodeposited Co‐Ni Electrocatalyst on Fe‐Modified Ni‐Foam for Alkaline Oxygen Evolution Reaction

A scalable magnetoelectrocatalyst design is demonstrated by imposing a magnetic field only during electrodeposition of the electrocatalyst to enhance catalysis of Ni active sites using less active Co, which has high magnetic saturation. This symbiosis using Ni, Co, and Fe modified Ni-foam outperforms conventional electrocatalysts and eliminates the application of a magnetic field during oxygen evolution in alkaline media.

Abstract

Applying external magnetic field facilitates the oxygen evolution reaction (OER), but such a strategy is impractical for large-scale applications. We introduce a scalable alternative by applying magnetic fields only during catalyst electrodeposition. We further propose a design principle for magnetoelectrocatalyst wherein electrocatalysis of active sites is enhanced by magnetic field impressed in the vicinity of active sites using a less active element having high magnetic saturation. This principle is demonstrated using monometallic systems (FTO/Ni and FTO/Co) and then extended it to develop a multimetallic magnetoelectrodeposited (MED) catalyst (NF/Fe-NiCo-MED). A Fe-modified Ni-foam (NF/Fe) substrate was prepared via galvanic displacement, onto which Ni, Co, or NiCo were electrodeposited under a 0.6 T field. The resulting NF/Fe-NiCo-MED magneto catalysts exhibited enhanced remanence, saturation magnetization, and ECSA and lower charge-transfer resistance compared to counterparts NF/Fe-NiCo-no MED deposited without external magnetic field. The NF/Fe-NiCo-MED demonstrated excellent OER performance, with a low overpotential of 273.26 mV at 100 mA/cm² and sustained stability for 72 h in alkaline media. Notably, NF/Fe-NiCo-MED outperforms benchmark NiCo-based layered double hydroxide (LDH) catalysts and even multimetallic systems operated under an external magnetic field during alkaline OER.

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