Direct Magnetic Reinforcement of Electrocatalytic ORR/OER with Electromagnetic Induction of Magnetic Catalysts

Abstract

Designing stable and efficient electrocatalysts for both oxygen reduction and evolution reactions (ORR/OER) at low‐cost is challenging. Here, a carbon‐based bifunctional catalyst of magnetic catalytic nanocages that can direct enhance the oxygen catalytic activity by simply applying a moderate (350 mT) magnetic field is reported. The catalysts, with high porosity of 90% and conductivity of 905 S m−1, are created by in situ doping metallic cobalt nanodots (≈10 nm) into macroporous carbon nanofibers with a facile electrospinning method. An external magnetic field makes the cobalt magnetized into nanomagnets with high spin polarization, which promote the adsorption of oxygen‐intermediates and electron transfer, significantly improving the catalytic efficiency. Impressively, the half wave‐potential is increased by 20 mV for ORR, and the overpotential at 10 mA cm−2 is decreased by 15 mV for OER. Compared with the commercial Pt/C+IrO2 catalysts, the magnetic catalyzed Zn–air batteries deliver 2.5‐fold of capacities and exhibit much longer durability over 155 h. The findings point out a very promising strategy of using electromagnetic induction to boost oxygen catalytic activity.

Spin-state reconfiguration induced by alternating magnetic field for efficient oxygen evolution reaction

“…Theoretical investigation discloses that the antiferromagnetic and ferromagnetic are strongly related with the exchange interaction of bonding and antibonding orbitals between magnetic ions and linked organic molecules 14 . Additionally, some reports uncover that the OER performance in magnetic catalysts are intensively interrelated to their spin configuration and exchange interaction 15 – 17 , because the number of unpaired electrons in four-electron reaction process cannot be conserved, leading to a spin-correlated catalytic activity. These findings inspire us to develop a feasible method to steer catalyst’s spin distribution, which can be used to realize a further breakthrough in OER performance.…”

Magnetocatalysis: The Interplay between the Magnetic Field and Electrocatalysis

“…With a moderate magnetic field, water splitting kinetics can be promoted significantly by using a ferromagnetic electrode such as Ni, Co, and their alloys. [14,15] The magnetism-independent reinforcement of catalytic efficiency can be explained by the magnetohydrodynamics effect induced by the Lorentz force, which acts either on ionic currents or oxygen/hydrogen bubble formation and release. [16] Galán-Mascarós et al found that the enhanced oxygen evolution reaction (OER) efficiency is closely related to the bulk magnetization of the catalysts and the pH value of the electrolyte.…”

Highly Curved Nanostructure‐Coated Co, N‐Doped Carbon Materials for Oxygen Electrocatalysis

“…[25] Among various bifunctional ORR/OER catalysts, metal-nitrogen-carbon (M-N-C) catalysts have become potential candidates. [26][27][28][29][30][31][32][33][34] Therefore, introducing highly curved carbon structures in M-N-C materials is a promising strategy to design active electrocatalysts.…”