Hang Yue,Sichen Huo,Xinyu Wang,Mingyi Wang,Heyuan Sun,Yanjie Chen,Ying Dai,Mingyang Liu,Jinlong Zou
Due to restrictive linear relationship between intermediates in adsorption evolution mechanism (AEM) of oxygen evolution reaction (OER), a higher overpotential must be overcome for conversion of *O to *OOH. Activating lattice oxygen mechanism (LOM) can address the AEM’s challenges by facilitating O-O coupling. However, via LOM pathway, extracting electrons from metal-oxygen (M−O) bonds usually results in structural instability. Herein, we propose an effective method to stabilize LOM-catalysts by combining cerium dioxide with cobalt phosphide (CeO 2 /CoP heterostructure). CeO 2 acts as an electron buffer to retain/provide electrons at different stages, while CoP with strong Co-P covalency enhances structural/catalytic stability in strongly-alkaline conditions. CeO 2 /CoP exhibits an OER overpotential of only 225 mV at 10 mA cm −2 . Initially, CeO 2 acquires electrons from CoP to accelerate surface reconstruction and form high-valence Co δ+ (CoOOH). Then, CoOOH acquires electrons from the 4 f -orbital of Ce through the Ce-O-Co interface, rather than from the M−O bond, thus ensuring OER stability. For water splitting, bifunctional CeO 2 /CoP-assembled electrolyzer requires a cell-voltage of only 1.54 V to achieve 10 mA cm −2 and retains 89.5 % of its activity after 72 h of cycling. It highlights that leveraging electron-buffering metal species can enhance the LOM stability, thereby enabling its application in bifunctional electrocatalysis.
Perovskite oxides are promising anodic electrocatalysts for alkaline saline water electrolysis, yet their performance is often limited by sluggish oxygen evolution reaction kinetics and competing chloride corrosion. Building on Pr0.1Sr0.9Co0.5Fe0.5O3 (PSCF), a candidate previously identified via our transfer learning paradigm, we further leveraged data-driven compositional searching of the A-site configuration, which led to an optimized catalyst with a proper Ce/Sr/Pr ratio (Ce-PSCF). The asymmetric Ce–O–Co motifs invoked a negative charge-transfer regime and activated the evolution of nonbonding oxygen (ONB) states, which reconciled the activity-stability trade-off and promoted a dual-site intramolecular lattice oxygen mechanism, as evidenced by promoted 18O–18O evolution. The electrolyzer with Ce-PSCF lowered the overpotential of the PSCF-based one by 100 mV at 300 mA cm–2 and exhibited 15-fold greater durability. Electrochemical analysis revealed a higher reaction order, promoted *OH coverage, and faster surface reconstruction on the Ce-incorporated electrocatalyst, indicating *OH-controlled chemical-step kinetics. Theoretical insight inferred a variation of the rate-determining step from O–O coupling to secondary OH– refilling with a reduced energy barrier from 0.68 to 0.54 eV. Moreover, ab initio molecular dynamics simulations visualized a dynamically strengthened affinity for OH– and significant repulsion of Cl–, arising from its intrinsic Lewis acidic and basic microenvironment.
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