Magnetically-altered eg-orbital occupancy to boost the two-electron oxygen reduction electrocatalysis for faster water decontamination

Herein, we demonstrate how the magnetic modulation of the e g -orbital occupancy of Co ions can become a novel approach to enhance the two-electron oxygen reduction reaction (2e - ORR) for advanced wastewater treatment by electro-Fenton (EF) process. Nickel foam (NF) substrate coated with ZIF67 was prepared and thermally treated to obtain ferromagnetic NF-supported Co/Co 3 O 4 cathodes, whose response to a small magnetic field was further evaluated in EF. The results show an increase of 62.3 % increase in H 2 O 2 yield and 46.5 % in faradaic efficiency, improving the degradation rate of the antibiotic sulfamerazine from 77.2 % to 92.4 % in 120 min. This enhancement is attributed to improved electron transfer facilitated by the alteration of e g -orbital occupancy of Co ions caused by spin regulation under the magnetic field, rather than to mass transport effects. Therefore, magnetic modulation of the e g -orbital occupancy emerges as a promising strategy to boost EF process for more efficient water decontamination. • Magnetoelectrocatalytic O 2 reduction reaction (ORR) using a ferromagnetic Co-MOF cathode. • The magnetic field-altered e g -orbital occupancy enhanced the ORR in electro-Fenton. • H 2 O 2 concentration rose by 62.3 %, along with Faradaic efficiency up to 46.5 %. • The enhanced electron transfer via spin regulation yielded a faster antibiotic degradation. • Magnetic field-assisted electrochemistry successfully combined with classical catalytic theory.