A High-Performance Ruddlesden–Popper Perovskite for Bifunctional Oxygen Electrocatalysis

Abstract

Highly active and stable bifunctional materials for the oxygen evolution/reduction reaction (OER/ORR) are critical for developing high-performance metal−air batteries and fuel cells. This study demonstrates the significantly enhanced electrocatalytic activity of a Ruddlesden− Popper (RP) perovskite (A n+1 B n O 3n+1 , n = 3) as a bifunctional material [i.e., RP-LaSr 3 (Co 0.5 Fe 0.5 ) 3 O 10−δ ] for oxygen electrocatalysis via an optimal doping strategy. The improved performance mainly benefits from the enhanced oxygen vacancies, the facile oxygen release and incorporation abilities, the synergistic interplay of Co and Fe together with the increased amounts of adsorbed OH − /O 2 , and the highly oxidative O 2 2− /O − . The more positive onset potential (E onset ) and the highest half wave potential (E 1/2 ) of RP-LaSr 3 (Co 0.5 Fe 0.5 ) 3 O 10−δ imply a better ORR activity relative to those of the benchmark Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 2.59 (BSCF) and the widely referred cubic perovskite (La 0.6 Sr 0.4 ) 0.95 Co 0.2 Fe 0.8 O 3−δ (CP-LSCF). Furthermore, this material enables the electrochemical reduction of O 2 by 4e − to OH − with an impressive stability. More importantly, RP-LaSr 3 Co 1.5 Fe 1.5 O 10−δ shows a largely narrowed potential gap (ΔE) and achieves its minimum value of 0.91 V, remarkably smaller than those of CP-LSCF (1.01 V), BSCF (1.04 V), and most of the state-of-the-art bifunctional materials. This study paves an attractive way to accurately fabricate RP-type perovskites as highly efficient and stable materials for bifunctional oxygen electrocatalysis.

Structural Variations of Metal Oxide‐Based Electrocatalysts for Oxygen Evolution Reaction

“…Besides typical perovskite with cubic structure, the perovskite family also includes many derivatives, such as double, [67] triple, [68] quadruple, [69] and layered perovskites. [70] Such flexibility in composition and structure [42] Copyright 2011, Wiley-VCH. b) Typical crystal structure of perovskite oxides.…”

“…Besides typical perovskite with cubic structure, the perovskite family also includes many derivatives, such as double, [ 67 ] triple, [ 68 ] quadruple, [ 69 ] and layered perovskites. [ 70 ] Such flexibility in composition and structure endows perovskites tunable electronic structure, which has close relationship with the catalytic activity and structural stability of OER catalysts. [ 71,72 ] Perovskites are potential alternatives for OER catalysts both in acid and alkaline medium.…”

Local-electrostatics-induced oxygen octahedral distortion in perovskite oxides and insight into the structure of Ruddlesden–Popper phases

“…In addition to directly demonstrating the distortion of oxygen octahedra at the faults in perovskite oxides, the findings in this work have further notable implications for the in-depth understanding of the structures of a variety of RP oxides and halides, which exhibit a very wide range of physical properties encompassing dielectric and unusual ferroic, multiferroic, electrocatalytic, and optical behavior 7 – 10 , 40 – 45 . As can be easily recognized from their general formula, A n + 1 B n X 3 n + 1 or equivalently AX[ABX 3 ] n , the presence of consecutive [AX] sublayers is a common structural feature irrespective of the value of n .…”

Oxygen Reduction Reaction Catalysed by Supported Nanoparticles: Advancements and Challenges

“…Consequently, systematically modified NPs have attracted growing interest for the advancement of ORR electrocatalyst. [14][15][16][17][18][19][20][21][22]…”

“…In recent times, nanostructures (NSs) including transition metal oxides (TMOs), mixed metal oxides (MMOs), metallic alloys, perovskites, metal‐organic frameworks (MOFs), etc. supported on various carbonaceous materials have been extensively investigated as cathode catalysts [14–17] . Owing to their synergistic effect, high O 2 ‐diffusion capability, anionic defects and significant hetero‐structure interfacial mechanism of supported nanoparticles (NPs) exhibit superior electrocatalytic activities.…”