Manipulating Spin Polarization of Defected Co3O4 for Highly Efficient Electrocatalysis

Abstract

Electrocatalytic water splitting is limited by kinetics-sluggish oxygen evolution, in which the activity of catalysts depends on their electronic structure. However, the influence of electron spin polarization on catalytic activity is ambiguous. Herein, we successfully regulate the spin polarization of Co3O4 catalysts by tuning the concentration of cobalt defects from 0.8 to 14.5%. X-ray absorption spectroscopy spectra and density functional theory calculations confirm that the spin polarization of Co3O4 is positively correlated with the concentration of cobalt defects. Importantly, the enhanced spin polarization can increase hydroxyl group absorption to significantly decrease the Gibbs free energy change value of the OER rate-determining step and regulate the spin polarization of oxygen species through a spin electron-exchange process to easily produce triplet-state O2, which can obviously increase electrocatalytic OER activity. In specific, Co3O4-50 with 14.5% cobalt defects exhibits the highest spin polarization and shows the best normalized OER activity. This work provides an important strategy to increase the water splitting activity of electrocatalysts via the rational regulation of electron spin polarization.

Integrated Photothermal Nanoreactors for Efficient Hydrogenation of CO2

“…The sample displayed small-sized Co nanoparticles regularly embedded in the silica matrix. The lattice spacing along a specific direction was 0.21 nm, which agrees with the (111) crystal plane of the cubic-phase Co [33,34]. The elemental mapping results confirmed the coating of silica and demonstrated the existence of a core-satellite structure (Fig.…”

Boosting oxygen evolution reaction performance via metal defect-induced lattice oxygen redox reactions on spinel oxides

“…However, further observation revealed that the oscillation amplitude of ZnFeO-CP-15 was slightly smaller than that of ZnFeO-C, suggesting that the former had a higher degree of disorder in the local coordination environment than the latter. 13 Both samples presented three dominant Fourier-transformed intensities (Fe–O, Fe–M 1 , and Fe–M 2 ) in the R -space, which correspond to the coordination of the Co–O, Fe ( O h )–M ( O h ), and Fe ( O h )–M ( T d ) or Fe ( T d )–M ( T d ) shells, respectively. 48,49 Compared with ZnFeO-C, the amplitudes of ZnFeO-CP-15 showed a decreasing trend at 2.60 and 3.16 Å.…”

“…5,6 However, due to their high cost, scarcity, and poor stability of noble metal catalysts, 3D transition metals and their derivatives have been extensively studied, with spinel and perovskite metal oxides being the most widely investigated. [7][8][9][10][11] Conventional OER mechanisms of spinel or perovskite catalysts follow the adsorbate evolution mechanism (AEM), 12,13 but most of the active sites in these catalysts are wasted. For example, in Co 3 O 4 , 14 1/3 of the cobalt occupies tetrahedral sites, and only this fraction can be used as active OER sites.…”

One-pot synthesis of NiFe nanoarrays under an external magnetic field as an efficient oxygen evolution reaction catalyst

“…According to the previous reports, electron spin polarization could enhance the catalytic activity of OER, because the unique OER steps from singlet reactant to the triplet product (↑OO↑) call for a spin-selective electron transfer. 43–46 Furthermore, the Fe and Ni catalysts have excellent OER catalytic activity. It is worth noting here that Ni and Fe occupy different d-orbitals that determine the electron transfer rate and reaction thermodynamics, which are intrinsically dependent on the cation's spin state.…”