Activity and stability trends of perovskite oxides for oxygen evolution catalysis at neutral pH (original) (raw)
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Double perovskites as a family of highly active catalysts for oxygen evolution in alkaline solution
Nature Communications, 2013
The electronic structure of transition metal oxides governs the catalysis of many central reactions for energy storage applications such as oxygen electrocatalysis. Here we exploit the versatility of the perovskite structure to search for oxide catalysts that are both active and stable. We report double perovskites (Ln 0.5 Ba 0.5)CoO 3 À d (Ln ¼ Pr, Sm, Gd and Ho) as a family of highly active catalysts for the oxygen evolution reaction upon water oxidation in alkaline solution. These double perovskites are stable unlike pseudocubic perovskites with comparable activities such as Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3 À d which readily amorphize during the oxygen evolution reaction. The high activity and stability of these double perovskites can be explained by having the O p-band centre neither too close nor too far from the Fermi level, which is computed from ab initio studies.
Bifunctional Perovskite Oxide Catalysts for Oxygen Reduction and Evolution in Alkaline Media
Chemistry, an Asian journal, 2015
Oxygen electrocatalysis, namely of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), governs the performance of numerous electrochemical energy systems such as reversible fuel cells, metal-air batteries, and water electrolyzers. However, the sluggish kinetics of these two reactions and their dependency on expensive noble metal catalysts (e.g,, Pt or Ir) prohibit the sustainable commercialization of these highly innovative and in-demand technologies. Bi-functional perovskite oxides have emerged as a new class of highly efficient non-precious metal catalysts (NPMC) for oxygen electrocatalysis in alkaline media. In this review, we discuss the state-of-the-art understanding of bifunctional properties of perovskites with regards to their OER/ORR activity in alkaline media, review the associated reaction mechanisms on the oxides surface and the related activity descriptors developed in recent literature. We also summarize the present strategies to modify their elect...
Chemistry of Materials, 2017
Oxygen electrocatalysis is at the heart of the emerging energy conversion and storage devices including reversible fuel cells and metal-air batteries. However, replacing the noble-metal-based oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalysts with affordable and robust alternatives remains challenging to date. Herein, we report a cation-ordered double perovskite oxide, i.e., PrBa 0.85-Ca 0.15 MnFeO 5+δ , with excellent stability and activity in both OER and ORR. The layered crystal structure provides ordered oxygen vacancy channels and a vast amount of surface oxygen defects, while the moderate amount of iron dopant keeps the B-site cations at high oxidation state with optimal e g fillings. Importantly, the DFT calculations along with the advanced TEM analysis verify that the incorporation of Ca at the A-site stabilizes the perovskite structure under potential bias. Such a bifunctional catalyst shows comparable, if not better, activity relative to the state-of-the-art perovskite oxides (e.g., Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3−δ) while demonstrating remarkably enhanced robustness. This work presents a rational approach of designing efficient, robust, and cost-effective perovskite oxide for oxygen electrocatalysis and sheds light on the influences of the crystallographic structure on the catalytic property.
Perovskite oxides: Oxygen electrocatalysis and bulk structure
1987
Perovskite type oxides were considered for use as oxygen reduction and generation electrocatalysts in alkaline electrolytes. Perovskite stability and electrocatalytic activity are studied along with possible relationships of the latter with the bulk solid state properties. A series of compounds of the type LaFe(x)Ni1(-x)O3 was used as a model system to gain information on the possible relationships between surface catalytic
Iron-Based Perovskites for Catalyzing Oxygen Evolution Reaction
The Journal of Physical Chemistry C, 2018
The slow kinetics of the oxygen evolution reaction (OER) is the main cause of energy loss in many low-temperature energy storage techniques, such as metal-air batteries and water splitting. A better understanding of both the OER mechanism and the degradation mechanism on different transition metal oxides is critical for the development of the next generation of oxides as OER catalysts. In this paper, we systematically investigated the catalytic mechanism and lifetime of ABO 3-δ perovskite catalysts for OER, where A = Sr or Ca and B = Fe or Co. During the OER process, the Fe-based AFeO 3-δ oxides with δ ≈ 0.5 demonstrate no activation of lattice oxygen or pH dependence of OER activity, which is different from the SrCoO 2.5 with similar oxygen 2p-band position relative to the Fermi level. The difference was attributed to the larger changes in the electronic structure during the transition from the oxygen-deficient brownmillerite structure to the fully-oxidized perovskite structure and the poor conductivity in Fe-based oxides, which hinders the uptake of oxygen from the electrolyte to the lattice under oxidative potentials. The low stability of Fe-based perovskites under OER conditions in basic electrolyte also contribute to the different OER mechanism compared with the Co-based perovskites. This work reveals the influence of transition metal composition and electronic structure on the catalytic mechanism and operational stability of perovskite OER catalysts.
Oxygen-deficient BaTiO3− perovskite as an efficient bifunctional oxygen electrocatalyst
Nano Energy, 2015
Perovskite oxide catalysts have emerged as the most promising bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalysts for electrochemical energy conversion and storage. In this work, a new type of oxygen-deficient BaTiO 3À x has been synthesized using a solgel method followed by a reductive heat treatment at 1300 1C in vacuum. The prepared perovskite nanoparticles have an average particle size on the order of 100 nm with uniform size distribution. X-ray diffraction shows that this perovskite catalyst consists of a significant amount of hexagonal BaTiO 3À x. State-of-the-art IrO 2 nanoparticles were also prepared in this work, which were used for reference and has excellent OER activity. Importantly, the oxygen-deficient perovskite catalysts exhibited high catalytic activity simultaneously for the ORR and the OER in alkaline electrolyte. The more challenged OER activity measured with the perovskite exceeds the IrO 2 catalyst at relatively low potentials (o1.6 V) evidenced by a much reduced onset potential (1.32 V) and increased current density. In order to clearly elucidate the structure of the oxygen-deficient BaTiO 3À x catalysts, X-ray and neutron diffraction experiments were further carried out, indicating that the hexagonal phase in the best performing BaTiO 3À x catalyst is oxygen-deficient with a stoichiometry of BaTiO 2.76. The oxygen vacancies in the perovskite crystal structure may lead to vastly enhanced electrocatalytic activity toward the ORR and OER. This work demonstrates a new type of highly efficient perovskite bifunctional catalyst for electrochemical energy technologies relying on oxygen electrocatalysis.
Catalysts, 2020
The selection and evaluation of electrocatalysts as candidate materials for industrial alkaline water electrolysis is fundamental in the development of promising energy storage and sustainable fuels for future energy infrastructure. However, the oxygen evolution reaction (OER) activities of various electrocatalysts already reported in previous studies are not standardized. This work reports on the use of perovskite materials (LaFeO3, LaCoO3, LaNiO3, PrCoO3, Pr0.8Sr0.2CoO3, and Pr0.8Ba0.2CoO3) as OER electrocatalysts for alkaline water electrolysis. A facile co-precipitation technique with subsequent thermal annealing (at 700 °C in air) was performed. Industrial requirements and criteria (cost and ease of scaling up) were well-considered for the selection of the materials. The highest OER activity was observed in LaNiO3 among the La-based perovskites, and in Pr0.8Sr0.2CoO3 among the Pr-based perovskites. Moreover, the formation of double perovskites (Pr0.8Sr0.2CoO3 and Pr0.8Ba0.2CoO3...
Perovskites in catalysis and electrocatalysis
Science (New York, N.Y.), 2017
Catalysts for chemical and electrochemical reactions underpin many aspects of modern technology and industry, from energy storage and conversion to toxic emissions abatement to chemical and materials synthesis. This role necessitates the design of highly active, stable, yet earth-abundant heterogeneous catalysts. In this Review, we present the perovskite oxide family as a basis for developing such catalysts for (electro)chemical conversions spanning carbon, nitrogen, and oxygen chemistries. A framework for rationalizing activity trends and guiding perovskite oxide catalyst design is described, followed by illustrations of how a robust understanding of perovskite electronic structure provides fundamental insights into activity, stability, and mechanism in oxygen electrocatalysis. We conclude by outlining how these insights open experimental and computational opportunities to expand the compositional and chemical reaction space for next-generation perovskite catalysts.