Co/Fe Bimetallic Coordination Polymers as Electrocatalysts for Oxygen Evolution and Urea Oxidation: Influence of Magnetic Field on Catalytic Activity

The development of efficient and durable electrocatalysts for the oxygen evolution reaction (OER) and urea oxidation reaction (UOR) is critical for advancing water electrolysis (WE) and urea electrolysis (UE). Herein, a series of one-dimensional Co/Fe bimetallic coordination polymers (CPs), formulated as [(CH 3 ) 2 NH 2 ] 2 [Co 1– x Fe x (SO 4 )(C 4 N 2 H 4 ) 2 (H 2 O) 3 ]·H 2 O·SO 4, were synthesized via a facile solvothermal route. The materials were evaluated as electrocatalysts for OER and UOR in alkaline media using a glassy carbon electrode. Among the series, Co 0.3 Fe 0.7 -CP exhibits the most superior OER activity, delivering a current density of 10 mA cm –2 at an overpotential of 270 mV, along with excellent operational stability over 70 h in 1.0 M KOH. Notably, the OER performance is significantly enhanced under an external magnetic field, where the overpotential required to achieve 50 mA cm –2 decreases from 350 to 310 mV as the magnetic field strength increases from 0 to 2000 G. For UOR, the optimized Co 0.3 Fe 0.7 -CP achieves a current density of 10 mA cm –2 at a low potential of 1.44 V vs RHE in 1.0 M KOH containing 0.33 M urea. These findings demonstrate that compositional tuning of bimetallic CPs, combined with magnetic-field-assisted electrocatalysis, represents an effective strategy for enhancing OER and UOR performance in alkaline energy conversion.