Estimating Hybridization of Transition Metal and Oxygen States in Perovskites from O <i>K</i>-edge X-ray Absorption Spectroscopy

Suntivich, Jin; Hong, Wonbin; Lee, Yueh Lin; Rondinelli, James M.; Yang, Wanli; Goodenough, John B; Dąbrowski, B.; Freeland, J. W.; Shao‐Horn, Yang

doi:10.1021/jp410644j

Cited by 387 publications

(445 citation statements)

References 39 publications

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“…However, salient information could be extracted from the TM3d-O2p pre-edge feature, which is determined by the t 2g -e g occupancy and TM-O covalency. 17,18 The O K-edge XAS spectra reveal that there are different oxygen electronic structures (t 2g -e g occupancy and TM-O covalency) on the surfaces of these materials. This is possibly explained by the presence of slight lithium excess on the surfaces of particles in the material annealed for a short length of time (6 hours), because the TM3d-O2p hybridization is interrupted by the presence of lithium in the TM 3b sites.…”

Section: Resultsmentioning

confidence: 99%

Influence of synthesis conditions on the surface passivation and electrochemical behavior of layered cathode materials

et al. 2014

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Understanding the relationship between materials synthesis and electrochemical behaviors should provide valuable knowledge to further the advancement of lithium-ion batteries. In this work, layered cathode materials {e.g., LiNi 0.4 Mn 0.4 Co 0.18 Ti 0.02 O 2 (NMCs)} were prepared under three different annealing conditions, i.e., 900 C for 6 hours, 8 hours, and 12 hours, respectively. The resulting materials exhibit equivalent crystal structures and morphologies yet likely different surface chemical environments. These materials show distinctively different resistances against the surface passivation/ reconstruction (reduction of the transition metals in the layered structure to form rock-salt and/or spinel phases) during electrochemical cycling (2.0-4.7 V vs. Li + /Li). In general, the materials annealed for longer durations exhibited lower tendencies to form the surface passivation layer. Furthermore, the surface passivation became less severe when the electrode materials were cycled under mild conditions, such as slow constant current charging-discharging as opposed to cyclic voltammetry. The present study correlates the synthetic conditions with the surface instability and the electrochemical performance in cathode materials, and provides new insights into improving synthetic protocols for battery materials.

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Section: Resultsmentioning

confidence: 99%

Influence of synthesis conditions on the surface passivation and electrochemical behavior of layered cathode materials

et al. 2014

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“…These assignments are consistent with our DFT band structure calculations and with assignments for LaCrO 3 powders. 16,45 As can be seen by examining the complete O K-edge XAS data set in Fig. 5, the broad feature E (labeled B3 in Fig.…”

Section: +mentioning

confidence: 90%

Hole-induced insulator-to-metal transition inLa1−xSrxCrO3

Zhang¹,

Du²,

Sushko³

et al. 2015

Phys. Rev. B

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We have investigated the evolution of the electronic properties of La 1-x Sr x CrO 3 (0 ≤ x ≤ 1) epitaxial films deposited by molecular beam epitaxy (MBE) using x-ray diffraction, x-ray photoemission spectroscopy, Rutherford backscattering spectrometry, x-ray absorption spectroscopy, electrical transport, and ab initio modeling. LaCrO 3 is an antiferromagnetic insulator whereas SrCrO 3 is a metal. Substituting Sr

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“…Ni > Co > Mn). 157 The eg-occupancy activity descriptor postulates that the number of electrons in the σ* states determines the metaloxygen bond strength, reducing the thermodynamic overpotential of ORR/OER on oxide surfaces along the lines of the Sabatier principle. Oxides that have too low an eg occupancy (eg < 1) bind to oxygen too strongly, while oxides that have too high an eg occupancy (eg > 1) bind too weakly.…”

Section: Electronic Structure Factors Of Perovskites Relevant To Catamentioning

confidence: 99%

Toward the rational design of non-precious transition metal oxides for oxygen electrocatalysis

Hong

Risch

Stoerzinger

et al. 2015

Energy Environ. Sci.

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REVIEWThis journal is © The Royal Society of Chemistry 2013 J. Name., 2013, 00, 1-3 | 1 In this Review, we discuss the state-of-the-art understanding of non-precious transition metal oxides that catalyze the oxygen reduction and evolution reactions. Understanding and mastering the kinetics of oxygen electrocatalysis is instrumental to making use of photosynthesis, advancing solar fuels, fuel cells, electrolyzers, and metal-air batteries. We first present key insights, assumptions and limitations of well-known activity descriptors and reaction mechanisms in the past four decades. The turnover frequency of crystalline oxides as promising catalysts is also put into perspective with amorphous oxides and photosystem II. Particular attention is paid to electronic structure parameters that can potentially govern the adsorbate binding strength and thus provide simple rationales and design principles to predict new catalyst chemistries with enhanced activity. We share new perspective synthesizing mechanism and electronic descriptors developed from both molecular orbital and solid state band structure principles. We conclude with an outlook on the opportunities in future research within this rapidly developing field. Broader ContextThe formation of chemical bonds is an energy dense mode of storing energy. In both nature and technology, the electrochemical generation and consumption of fuels is one of the most efficient routes for energy usage. Solar and electrical energy can be stored in chemical bonds by splitting water or metal oxides to produce hydrogen and metal. These compounds can then be oxidized to produce energy when coupled to the reduction of oxygen. However, these device efficiencies are severely limited by the catalysis of oxygen electrochemical processes -namely the oxygen reduction reaction and oxygen evolution reaction, which have slow kinetics. Non-precious transition metal oxides show promise as cost-effective substitutes for noble metals in commercially viable renewable energy storage and conversion devices. Furthermore, this class of materials has ben efitted from a wealth of spectroscopic and first-principles studies in the past few decades, providing the frameworks and theories needed to understand the electronic structure and design optimal catalysts. The incredibly diverse range of chemistries and physical properties that can be explored in oxide families afford numerous degrees of freedom for conducting systematic investigations relating intrinsic mat erial properties to catalytic performance. Here, we present background on the fundamental concepts in catalysis for the rational design of transition metal perovskite oxide catalysts for oxygen electrocatalysis and critically examine the current understanding a nd its impact on future directions of perovskite catalysts.

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Estimating Hybridization of Transition Metal and Oxygen States in Perovskites from O K-edge X-ray Absorption Spectroscopy

Cited by 387 publications

References 39 publications

Influence of synthesis conditions on the surface passivation and electrochemical behavior of layered cathode materials

Influence of synthesis conditions on the surface passivation and electrochemical behavior of layered cathode materials

Hole-induced insulator-to-metal transition inLa1−xSrxCrO3

Toward the rational design of non-precious transition metal oxides for oxygen electrocatalysis

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