Atomic‐Scale Insights into Surface Lattice Oxygen Activation at the Spinel/Perovskite interface of Co₃O₄/La_0.3Sr_0.7CoO₃

Abstract

Surface lattice oxygen in transition‐metal oxides plays a vital role in catalytic processes. Mastering activation of surface lattice oxygen and identifying the activation mechanism are crucial for the development and design of advanced catalysts. A strategy is now developed to create a spinel Co3O4 /perovskite La0.3Sr0.7CoO3 interface by in situ reconstruction of the surface Sr enrichment region in perovskite LSC to activate surface lattice oxygen. XAS and XPS confirm that the regulated chemical interface optimizes the hybridized orbital between Co 3d and O 2p and triggers more electrons in oxygen site of LSC transferred into lattice of Co3O4 , leading to more inactive O2− transformed into active O2−x. Furthermore, the activated Co3O4/LSC exhibits the best catalytic activities for CO oxidation, oxygen evolution, and oxygen reduction. This work would provide a fundamental understanding to explain the activation mechanism of surface oxygen sites.

Self‐Assembled Ruddlesden–Popper/Perovskite Hybrid with Lattice‐Oxygen Activation as a Superior Oxygen Evolution Electrocatalyst

“…The metal 3d‐oxygen 2p covalency can be further directly explored by the O K ‐edge XAS spectra, considering that the pre‐edge peak below ≈532 eV in the O‐ K XAS spectra corresponds to the unoccupied O 2p orbitals hybridized with transition metal 3d orbitals. [ 30,48–51 ] As shown in Figure 3e, lower pre‐edge energy position and higher intensity of the pre‐edge peak in RP/P‐LSCF were observed as compared with RP‐LSCF and P‐LSCF, demonstrating the enhanced covalency of metal–oxygen bond. According to previous theoretical and experimental studies, the lattice‐oxygen involvement in OER is triggered by the great covalency of metal–oxygen bond, which can shift the electroactive sites from metal cations to oxygen anions due to the formation of ligand hole.…”

“…The fast oxygen‐ion diffusion in RP/P‐LSCF is likely related to the layered RP structure and unique interface. [ 30,53–55 ] Of note, the intrinsic OER activity among RP/P‐LSCF, RP‐LSCF, and P‐LSCF catalysts was found to strongly correlate with the oxygen‐ion diffusion rate, as displayed in Figure 4b. In addition, the hybridization factor derived from the prepeak of O‐ K XAS spectra (Figure S7, Supporting Information), quantificationally representing the metal–oxygen covalency, [ 50,51 ] also shows nearly linear relationship with the intrinsic OER activity of catalysts (Figure 4c).…”

“…Constructing hybrids with interfacial interaction between the components has emerged as an effective way to improve the catalytic efficiency. [ 28–31 ] The hybrid structures can usually trigger some novel physical/chemical properties, which is crucial to promoting their electrocatalytic performance. On the one hand, the interface can serve as new catalytic actives with the optimized electronic structure through the existence of charge transfer and lattice stress between the multiple compounds.…”

“…On the one hand, the interface can serve as new catalytic actives with the optimized electronic structure through the existence of charge transfer and lattice stress between the multiple compounds. [ 30–33 ] On the other hand, the hybrid systems can induce some synergetic effects enabling to stabilize catalytic sites, and achieve a desirable electrocatalytic stability. [ 34,35 ] Therefore, we believe that the formation of RP/perovskite hybrid may be a viable way to regulate the electronic structure and accordingly boost the electrocatalytic performance.…”

Identifying and Engineering Active Sites at the Surface of Porous Single-Crystalline Oxide Monoliths to Enhance Catalytic Activity and Stability

“…[1][2][3][4][5] Activation of oxygen at the active sites that have unsaturated coordination structures therefore plays a key role to lower operation temperature in many catalytic oxidation reactions; however, the competitive adsorption of reactants would block the chemisorption of oxygen and hence prohibit the activation of oxygen at the active sites. [6][7][8][9] In this case, higher operation temperature would be required to activate oxygen in these catalytic reactions. Activation of lattice oxygen at the surface of catalysts would provide an alternative to enhance the catalytic activity in oxidation reactions.…”