II. Structure of Perovskites 1982 A. Crystal Structure 1982 B. Nonstoichiometry in Perovskites 1983 1. Oxygen Nonstoichiometry 1983 2. Cation Nonstoichiometry 1984 C. Physical Properties 1985 D. Adsorption Properties 1986 1. CO and NO Adsorption 1986 2. Oxygen Adsorption 1987 E. Specific Surface and Porosity 1987 F. Thermal Stability in a Reducing Atmosphere 1989 III. Acid−Base and Redox Properties 1990 A. Acidity and Basicity 1990 B. Redox Processes 1991 1. Kinetics and Mechanisms 1992 2. Reduction−Oxidation Cycles 1993 C. Ion Mobility 1993 1. Oxygen Transport 1993 2. Cation Transport 1994 IV. Heterogeneous Catalysis 1995 A. Oxidation Reactions 1995 1. CO Oxidation 1995 2. Oxidation of Hydrocarbons 1996 B. Pollution Abatement 2001 1. NOx Decomposition 2001 2. Exhaust Treatment 2002 3. Stability 2004 C. Hydrogenation and Hydrogenolysis Reactions 2004 1. Hydrogenation of Carbon Oxides 2004 2. Hydrogenation and Hydrogenolysis Reactions 2006

Chemical structures and performance of perovskite oxides.

Catalytic removal of NO

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.

http://science.sciencemag.org/content/sci/358/6364/751.full.pdf

Perovskites in catalysis and electrocatalysis

Oxidation into CO2 is a major solution to CO abatement in air depollution treatments. The development of catalytic converters led to an extraordinary high number of publications on metal catalysts during the last fifty years. Due to the increasing price of noble metals and to remarkable progresses in oxide syntheses, catalytic oxidation of carbon monoxide over oxide catalysts has recently gained in interest, even if some oxides are known to present remarkable activity since the beginning of the 20th century. In this Review, the kinetics and mechanism of CO oxidation on single and mixed oxides are examined, alongside the catalyst structures

Catalytic Oxidation of Carbon Monoxide over Transition Metal Oxides

Reduction/Evolution Catalysts for Low-Temperature Electrochemical Devices Dengjie Chen,†,⊥,∇ Chi Chen,†,⊥ Zarah Medina Baiyee,† Zongping Shao,‡,§ and Francesco Ciucci*,†,∥ †Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China ‡State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry & Chemical Engineering, Nanjing Tech University, No. 5 Xin Mofan Road, Nanjing 210009, China Department of Chemical Engineering, Curtin University, Perth, Western Australia 6845, Australia Department of Chemical and Biomolecular Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China

Nonstoichiometric Oxides as Low-Cost and Highly-Efficient Oxygen Reduction/Evolution Catalysts for Low-Temperature Electrochemical Devices

The high expectations present-day society has for catalysis in solving the energy crisis, in coping with environmental pollution, and in providing fertilizers and food have made research in catalysis the focus of interest in many adjacent fields. As an example, the science of solid surfaces in vacuum is explored for its relevance to and experimentally, a link has indeed been e ~ t a b l i s h e d . ~ Perhaps of even more importance, new interest has been stimulated in the links between solid-state physics and chemistry and the characteristics of solid catalysts. In earlier years, this connection had of course been explored on the heels of the spectacular development of semiconductor physics,\" but the fact that the best-studied semiconductors were poor catalysts has impeded progress in the establishment of detailed relationships between collective electrical properties and catalysis. Even so, a general relation between catalytic activity and the width of the band gap of a semiconductor has been recognized,' notwithstanding the frequent exceptions. Not only collective electrical properties, but also collective magnetic properties and ferroelectric properties have in those early years been explored in relation to catalytic characteristics. The relation was indeed established in work on the ferromagnetic man anese perovskite La~,6sSro,3sMn039 and on the ferroelectric perovskite KNbO,,' but the effects were small, which is perhaps not surprising. I ' The study of collective electron effects in metallic catalysts, I2-I4 which was initially partly based on the now ~ u p e r s e d e d ~ ~ . ' ~ rigid-band model of alloy systems such as Cu-Ni and Ag-Pd, has recently taken an interesting turn in the proposed relation between spin fluctuations connected with ma netic interactions and the momentum transfer t o a desorbing or reacting adatom. Surveying the relations between solid-state chemistry and catalysis, it becomes evident that in particular the number and type of localized defects in the solid have been successfully correlated with catalytic activity, e.g., for dislocations and steps on metal surface^,^^.^^ for surface states split off from the conduction band in semiconductors,21 and for anion vacancies or cation vacancies in insulators22 and s e m i c ~ n d u c t o r s . ~ ~ ~ ~ ~ In the present series of lectures on solid-state chemistry and catalysis, further examples of the role of anion and cation vacancies are given by Sleight, Schuit, and Longo. The topic of the present paper, defect chemistry of perovskite-type catalysts for oxidation-reduction processes, has received some stimulus from the suggestions that LaCo03, LaMn03, and their derivatives might be interesting catalysts for application in fuel cell electrodes2' and in the conversion of N O and C O from automotive e x h a ~ s t . ~ ~ ~ ~ In the following, the reduction of N O with CO and H2, and the oxidation of CO with O2 will be used as test reactions. We will explore the relationships between the catalytic activity and the defect chemistry of perovskitelike cobaltites, manganites, chromites, and ruthenates. The crystal structure of perovskite (CaTi03) is shown in FIGURE 1. The 97.1,

L.E. Trimble

Papers

Defect chemistry and catalysis in oxidation and reduction over perovskite-type oxides

Perovskite-like La1−xKxMnO3 and related compounds: Solid state chemistry and the catalysis of the reduction of NO by CO and H2

Perovskites containing ruthenium as catalysts for nitric oxide reduction

The activity of La0.7Sr0.3MnO3 without Pt and La0.7Pb0.3MnO3 with varying Pt contents for the catalytic oxidation of CO

Exploration of perovskite-like catalysts: Ba2CoWO6 and Ba2FeNbO6 in NO reduction and CO oxidation