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Probing Dynamic Self-Reconstruction on Perovskite Fluorides toward Ultrafast Oxygen Evolution.

ABSTRACT: Exploring low cost, highly active, and durable electrocatalysts for oxygen evolution reaction (OER) is of prime importance to boost energy conversion efficiency. Perovskite fluorides are emerging as alternative electrocatalysts for OER, however, their intrinsically active sites during real operation are still elusive. Herein, the self-reconstruction on newly designed NiFe coupled perovskite fluorides during OER process is demonstrated. In situ Raman spectroscopy, ex situ X-ray absorption spectroscopy, and theoretical calculation reveal that Fe incorporation can significantly activate the self-reconstruction of perovskite fluorides and efficiently lower the energy barrier of OER. Benefiting from self-reconstruction and low energy barrier, the KNi_0.8 Fe_0.2 F₃ @nickel foam (KNFF2@NF) electrocatalyst delivers an ultralow overpotential of 258 mV to afford 100 mA cm^-2 and an excellent durability for 100 h, favorably rivaling most the state-of-the-art OER electrocatalysts. This protocol provides the fundamental understanding on OER mechanism associated with surface reconstruction for perovskite fluorides.

SUBMITTER: Zhang J

PROVIDER: S-EPMC9507342 | biostudies-literature | 2022 Sep

REPOSITORIES: biostudies-literature

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Probing Dynamic Self-Reconstruction on Perovskite Fluorides toward Ultrafast Oxygen Evolution.

Zhang Jing J Ye Yu Y Wang Zhenbin Z Xu Yin Y Gui Liangqi L He Beibei B Zhao Ling L

Advanced science (Weinheim, Baden-Wurttemberg, Germany) 20220722 27

Exploring low cost, highly active, and durable electrocatalysts for oxygen evolution reaction (OER) is of prime importance to boost energy conversion efficiency. Perovskite fluorides are emerging as alternative electrocatalysts for OER, however, their intrinsically active sites during real operation are still elusive. Herein, the self-reconstruction on newly designed NiFe coupled perovskite fluorides during OER process is demonstrated. In situ Raman spectroscopy, ex situ X-ray absorption spectr ...[more]

PMID: 35869034

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Project description:Compositionally versatile, nonstoichiometric, mixed ionic-electronic conducting metal oxides of the form A n+1B n O3n+1 (n = 1 → ∞; A = rare-earth-/alkaline-earth-metal cation; B = transition-metal (TM) cation) remain a highly attractive class of electrocatalysts for catalyzing the energy-intensive oxygen evolution reaction (OER). The current design strategies for describing their OER activities are largely derived assuming a static, unchanged view of their surfaces, despite reports of dynamic structural changes to 3d TM-based perovskites during OER. Herein, through variations in the A- and B-site compositions of A n+1B n O3n+1 oxides (n = 1 (A2BO4) or n = ∞ (ABO3); A = La, Sr, Ca; B = Mn, Fe, Co, Ni), we show that, in the absence of electrolyte impurities, surface restructuring is universally the source of high OER activity in these oxides and is dependent on the initial oxide composition. Oxide surface restructuring is induced by irreversible A-site cation dissolution, resulting in in situ formation of a TM oxyhydroxide shell on top of the parent oxide core that serves as the active surface for OER. The rate of surface restructuring is found to depend on (i) composition of A-site cations, with alkaline-earth-metal cations dominating lanthanide cation dissolution, (ii) oxide crystal phase, with n = 1 A2BO4 oxides exhibiting higher rates of A-site dissolution in comparison to n = ∞ ABO3 perovskites, (iii) lattice strain in the oxide induced by mixed rare-earth- and alkaline-earth-metal cations in the A-site, and (iv) oxide reducibility. Among the in situ generated 3d TM oxyhydroxide structures from A n+1B n O3n+1 oxides, Co-based structures are characterized by superior OER activity and stability, even in comparison to as-synthesized Co-oxyhydroxide, pointing to the generation of high active surface area structures through oxide restructuring. These insights are critical toward the development of revised design criteria to include surface dynamics for effectively describing the OER activity of nonstoichiometric mixed-metal oxides.

Dataset Information

Probing Dynamic Self-Reconstruction on Perovskite Fluorides toward Ultrafast Oxygen Evolution.

Publications

Probing Dynamic Self-Reconstruction on Perovskite Fluorides toward Ultrafast Oxygen Evolution.

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