Regulating the Spin Polarization of NiFe Layered Double Hydroxide for the Enhanced Oxygen Evolution Reaction

Abstract

The oxygen evolution reaction (OER) is an electrochemical process that involves the spin-dependent conversion of singlet OH–/H2O to triplet O2. However, the sluggish dynamics associated with this reaction severely limits its efficiency in electrochemical water splitting. Fortunately, the utilization of a magnetic field can significantly enhance the spin selectivity and accelerate reaction kinetics. Herein, we report a unique strategy to regulate the spin polarization of NiFe layered double hydroxide (NiFe-LDH) by harnessing an internal magnetic field induced by a built-in magnetic core. The exchange bias effect between the magnetic core and NiFe-LDH can selectively remove electrons with opposite magnetic moments, thereby reducing magnetoresistances and minimizing spin scattering during electron transport. Benefiting from this bias effect, the obtained catalyst exhibits excellent OER performance with a low overpotential of 196 mV at a current density of 30 mA cm–2. Furthermore, density functional theory (DFT) calculations further confirm that the exchange bias effect can increase the hybrid strength of Fe-3d and O-2p orbitals while decreasing the adsorption energy of the reactant intermediates, thus accelerating the generation of paramagnetic oxygen.

The spin polarization strategy regulates heterogeneous catalytic activity performance: from fundamentals to applications

“…Furthermore, Cao et al 109 proposed a novel approach to regulating the electron spin by constructing an internal field utilizing Fe 3 O 4 as a spherical core to synthesize Fe 3 O 4 @NiFe-LDH. The magnetic core and NiFe-LDH exhibit an exchange bias effect, effectively modulating the electronic structure and regulating the electron spin state.…”

Activating lattice oxygen by a defect-engineered Fe2O3–CeO2 nano-heterojunction for efficient electrochemical water oxidation

“…3–6 The anodic oxygen evolution reaction (OER) is currently believed to be the major bottleneck of water electrolysis due to the sluggish reaction kinetics and limited performance of electrocatalysts. 7,8 Catalysts following the traditional adsorbate evolution mechanism (AEM) could not overcome the intrinsic overpotential threshold of around 370 mV limited by the Sabatier's principle and linear-scaling relationship of key intermediates (*O, *OH, *OOH, etc. ), impeding the improvement of catalytic performance.…”