Exploring highly efficient catalysts for the oxygen evolution reaction (OER) is essential for water electrolysis. Cost‐effective transition‐metal oxides with reasonable activity are raising attention. Recently, OER reactants' and products' differing spin configurations have been thought to cause slow reaction kinetics. Catalysts with magnetically polarized channels could selectively remove electrons with opposite magnetic moment and conserve overall spin during OER, enhancing triplet state oxygen molecule evolution. Herein, antiferromagnetic inverse spinel oxide LiCoVO4 is found to contain d7 Co2+ ions that can be stabilized under active octahedral sites, possessing high spin states S = 3/2 (t2g5eg2). With high spin configuration, each Co2+ ion has an ideal magnetic moment of 3 µB, allowing the edge‐shared Co2+ octahedra in spinel to be magnetically polarized. Density functional theory simulation results show that the layered antiferromagnetic LiCoVO4 studied contains magnetically polarized channels. The average magnetic moment (µave) per transition‐metal atom in the spin conduction channel is around 2.66 µB. Such channels are able to enhance the selective removal of spin‐oriented electrons from the reactants during the OER, which facilitates the accumulation of appropriate magnetic moments for triplet oxygen molecule evolution. In addition, the LiCoVO4 reported has been identified as an oxide catalyst with excellent OER activity.

Rational design of active oxygen evolution reaction (OER) catalysts is critical for the overall efficiency of water electrolysis. The differing spin states of the OER reactants and products is one of the factors that slows OER kinetics. Thus, spin conservation plays a crucial role in enhancing OER performance. In this work, ferromagnetic (FM)–antiferromagnetic (AFM) Fe3O4@Ni(OH)2 core–shell catalysts are designed. The interfacial FM–AFM coupling of these catalysts facilitates selective removal of electrons with spin direction opposing the magnetic moment of FM core, improving OER kinetics. The shell thickness is found critical in retaining the coupling effect for OER enhancement. The magnetic domain structure of the FM core also plays a critical role. With a multiple domain core, the applied magnetic field aligns the magnetic domains, optimizing the electron transport process. A significant enhancement of OER activity is observed for the multiple domain core catalysts. With a single‐domain FM core with ordered magnetic dipoles, the spin‐selective electron transport with minimal scattering is facilitated even without an applied magnetic field. A magnetism/OER activity model therefore hypothesizes that depends on two main parameters: interfacial spin coupling and domain structure. These findings provide new design principles for active OER catalysts.

The efficiency of electrolytic hydrogen production is limited by the slow reaction kinetics of oxygen evolution reaction (OER). Surface-reconstructed ferromagnetic (FM) catalysts with as pin-pinning effect at the FM/oxyhydroxide interface could enhance the spin-dependent OER kinetics. However,inreal-life applications,electrolyzersare operated at elevated temperature,w hichm ay disrupt the spin orientations of FM catalysts and limit their performance.I nt his study,w e prepared surface-reconstructed SmCo 5 /CoO x H y ,w hich possesses polarized spins at the FM/oxyhydroxidei nterface that lead to excellent OER activity.These interfacial polarized spins could be further aligned through am agnetization process, which further enhanced the OER performance.Moreover,the operation temperature was elevated to mimic the practical operation conditions of water electrolyzers. It was found that the OER activity enhancement of the magnetized SmCo 5 / CoO x H y catalyst could be preserved up to 60 8 8C.

The dioxygen molecule has two bound states, singlet and triplet, which are different in energy, lifetime, and reactivity. In the context of oxygen electrocatalysis as applied to fuel cells and water splitting the involved O2 is typically considered to be exclusively in its triplet ground state. However, applying spin-conservation rules for the transformation between triplet O2 and singlet OH−/H2O reaction intermediates predicts an additional free energy barrier associated with the required spin flip. As a result, for conditions under which both can form, the formation of triplet dioxygen from the singlet OH−/H2O might be slower than the formation of singlet O2. Correspondingly, singlet O2 might be more active than triplet O2 in the oxygen reduction reaction. Here, we discuss the possible existence and influence of singlet oxygen in oxygen electrocatalysis. Some perspectives for studying singlet oxygen in oxygen electrocatalysis are also provided.

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