Chirality functionalization coordinates with an external magnetic field for enhancing the oxygen evolution reaction of water electrolysis

Abstract

The anodic oxygen evolution reaction (OER) is a kinetic bottleneck in electrocatalytic water splitting due to its complex four-electron transfer, with efficient electronic modulation strategies lacking. Herein, we combine chiral functionalization with external magnetic fields (EMFs) to serve as endogenous and exogenous regulators, respectively, for manipulating electron spin states to improve the OER performance. Grafting chiral ligands (D-Pen, D-Cys, and D-Phe) onto CoFeO_x reduces the overpotential from 365 mV (bare) to 356, 352, and 350 mV at 10 mA cm⁻²; under 0.8 T EMF, D-Phe@CoFeO_x's overpotential further drops to 315 mV, which is much lower than that of its achiral counterpart under the same conditions (355.5 mV@0.8 T). Quantitative analysis revealed that the total current density increase (j₃) of chiral CoFeO_x under a magnetic field exceeded the sum of chirality-induced (j₁) and magnetic field-induced (j₂) increases (j₃ > j₂ + j₁), demonstrating a synergistic effect between chirality functionalization and the external magnetic effect that significantly enhances the OER performance. Density functional theory (DFT) calculations provided the following energy barriers: 0.77 eV (CoFeO_x), 0.73 eV (CoFeO_x + M, ΔR₁ = 0.04 eV), 0.64 eV (CoFeO_x@D-Phe, ΔR₂ = 0.13 eV), and 0.43 eV (CoFeO_x@D-Phe + M, ΔR₃ = 0.34 eV). ΔR₃ > ΔR₁ + ΔR₂ further corroborates the synergistic mechanism. This work establishes a promising dual spin-regulation strategy for efficient modulation of electron spin states in OER electrocatalysts, offering theoretical and experimental insights into overcoming the kinetic bottleneck of OER-dominated processes such as water splitting and metal–air batteries.