Chirality-Magnetism Coupling for Spin-Catalytic Oxygen Evolution

Spin-mediated promotion is emerging as a key strategy to overcome spin conservation constraints in the oxygen evolution reaction (OER) of water splitting, where magnetic fields have proven effective; however, they exert little effect on the common weak-magnetic-susceptibility electrocatalysts. Herein, we impart structural chirality into an antiferromagnetic electrocatalyst (using NiO as a model) through lattice distortions, and the coupling of the chiral structure and external magnetic fields cooperatively induces electron spin polarization, thereby achieving remarkable OER activity improvement. Theoretical and experimental results reveal that the electron spin polarization of chiral NiO is exceptionally sensitive to external magnetic fields, exhibiting a distinct dependence on field directions. A magnetic field oriented with the electron propagation direction for L-NiO and the opposite magnetic orientation for D-NiO engenders the optimal match and maximizes the spin-polarized electron transfer, facilitating efficient spin-exchange coupling and a more feasible evolution of high spin-multiplicity reaction intermediates. Therefore, L-NiO and D-NiO under optimal magnetic fields yield current densities approximately 7.5- and 6.2-fold higher than achiral A-NiO, respectively. This work broadens the applicability of magnetic fields in boosting OER activity, establishing a new paradigm of leveraging chirality-magnetism coupling for highly efficient spin-dependent catalysis.