Correlating Surface Crystal Orientation and Gas Kinetics in Perovskite Oxide Electrodes

Fernández, Abel; Chakraborty, Tanmoy; Luo, Aileen; Pesquera, David; Das, Sujit; Velarde, Gabriel; Thoréton, Vincent; Kilner, John A.; Ishihara, Takeshi; Nemšák, Slavomír; Crumlin, Ethan J.; Ertekin, Elif; Martin, Lane W.

doi:10.1002/adma.202100977

Cited by 23 publications

(34 citation statements)

References 57 publications

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“…Despite many studies suggesting that precious metal current collectors and/or impurities can impact the performance of oxygen-exchange-enabled devices, [45][46][47][48] precious metal current collectors are still routinely used to transport electronic species into/out of oxygen exchange materials in Electrical Conductivity Relaxation, 36,[49][50][51][52][53][54][55][56][57][58] and Electrical Impedance Spectroscopy 59,60 oxygen exchange experiments. The results here demonstrate that precious metal current collectors are not necessarily inert (i.e.…”

Section: Discussionmentioning

confidence: 99%

“…However, despite the fact that precious metal surface additions are well known to improve the performance of the MIEC materials used as SOC electrodes, oxygen sensors, vehicular catalytic converters etc., [45][46][47][48] an examination of how current collectors (especially the precious metal current collectors commonly used in the existing oxygen surface exchange literature 36,40,[49][50][51][52][53][54][55][56][57][58][59][60][61][62] ), affect oxygen surface exchange properties is less clear. This uncertainty is perpetuated by the fact that (1) today's most-common k chem , k o , k q, and R s measurement techniques (i.e.…”

Section: Introductionmentioning

confidence: 99%

“…Despite these reports, precious metal current collectors are still being actively used to measure the oxygen surface exchange properties of MIEC materials. 36,[49][50][51][52][53][54][55][56][57][58][59][60] Hence, the rst objective of this work was to dramatically demonstrate the role that even minute amounts of unpolarized precious metals can have on the k chem of MIEC materials. The second objective of this work was to go beyond the aforementioned past studies and identify any local chemistry changes likely responsible for the observed k chem alteration.…”

Section: Introductionmentioning

confidence: 99%

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Pt current collectors artificially boosting praseodymium doped ceria oxygen surface exchange coefficients

Burye

Nicholas

2021

J. Mater. Chem. A

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Pt current collectors artificially boosting praseodymium doped ceria oxygen surface exchange coefficients

Burye

Nicholas

2021

J. Mater. Chem. A

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“…First, we studied 20-nm-thick films of LSCO deposited on the LaAlO 3 (001), (LaAlO 3 ) 0.3 (Sr 2 TaAlO 6 ) 0.7 (LSAT) (001), and SrTiO 3 (001) substrates, corresponding to biaxial strains of −1.22%, 0.87%, and 1.79%, respectively, imposed on the LSCO; henceforth referred to as LSCO/LaAlO 3 (−1.22%), LSCO/LSAT (+0.87%), and LSCO/SrTiO 3 (+1.79%) heterostructures. Second, we studied 20-nm-thick films of LSCF deposited on LSAT (001), SrTiO 3 (001), and DyScO 3 (110) substrates, corresponding to biaxial strains of −0.97%, −0.02%, and 1.09%, respectively, [19,20] imposed on the LSCF; henceforth referred to as LSCF/LSAT (−0.97%), LSCF/SrTiO 3 (−0.02%), and LSCF/DyScO 3 (+1.09%) heterostructures. All films were grown via pulsed-laser deposition (Experimental Section).…”

Section: Synthesis and Characterizationmentioning

confidence: 99%

“…All films were grown via pulsed-laser deposition (Experimental Section). [20] Following film growth, X-ray diffraction studies (Experimental Section) were carried out to characterize the resulting structures and strain states (Figure 1). The systematic decrease in the out-of-plane c lattice parameter with increasing tensile strain is apparent in both the LSCO and LSCF films as a progressive shift of the 002-diffraction condition to higher 2θ angles (Figure 1a,b).…”

Section: Synthesis and Characterizationmentioning

confidence: 99%

Strain‐Induced Orbital Contributions to Oxygen Electrocatalysis in Transition‐Metal Perovskites

Fernández

Caretta

Das

et al. 2021

Advanced Energy Materials

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B site have shown high activities and represent a cost-effective alternative to expensive noble metal-based catalysts; however, gas exchange at these perovskite surfaces remains the limiting factor for high efficiency in electrochemical devices. [1][2][3] The development of perovskites with high activity has historically relied on brute-force compositional screening involving the synthesis and testing of numerous bulk-ceramic samples to establish an intuition for chemical trends that can guide researchers to highly active compositions. More recently, however, there has been a significant push to develop electronic descriptors for predicting electrochemical activity. [4][5][6][7] This work has led to the identification of several electronic descriptors that are closely correlated with high activity for ORR and OER catalysts, including the relative position of the oxygen 2p band center, [6] the BO bond covalency, [8] and, in particular, the occupancy of the e g orbitals. [5,9] For example, e g orbital occupation has been shown to be strongly correlated with the B-site-dependent chemical activity trends, and an "ideal" e g occupancy of ≈1.2 electrons has been used as the justification for high activities in LaNiO 3 and Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ (BSCF) catalysts. [5,9,10] As such, the development of electronic descriptors has already proved fruitful in identifying compositions with high activities and, in turn, developing synthetic control of materials properties to tune the electronic structure toward these ideal values could unlock a new way to optimize materials.In parallel to the development of these electronic descriptors, researchers have leveraged thin-film-based studies to understand how manipulation of the lattice structure of these perovskites can affect the electrochemical activity. Several studies have focused on the role of epitaxial strain in perovskite oxides for controlling electrochemical activity. [11][12][13][14][15][16][17] Reports have noted enhanced electrochemical activities in cobalt-and ironbased perovskites under biaxial-tensile strain driven by straininduced changes to surface chemistry [12] or suggested electronic contributions as the driving force for enhanced electrochemical activity under tensile strain. [13,14,18] Meanwhile, strain-induced changes to e g occupancy have been proposed as the mechanism of enhanced ORR/OER activities in LaNiO 3 films under biaxial compressive strain. [16] This discrepancy suggests that straininduced changes to electronic structure may be dependent on the identity of the B-site cation and calls for more direct studies Epitaxial strain has been shown to produce dramatic changes to the orbital structure in transition metal perovskite oxides and, in turn, the rate of oxygen electrocatalysis therein. Here, epitaxial strain is used to investigate the relationship between surface electronic structure and oxygen electrocatalysis in prototypical fuel cell cathode systems. Combining high-temperature electricalconductivity-relaxation studies and synchrotron-...

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Surface Space‐Charge Potential and Oxygen Surface Exchange Coefficient of SrTiO₃: The Effect of Surface Orientation

Kler

Börgers

Souza

2022

Adv Materials Inter

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18O2/16O2 exchange experiments on terminated (100), (110), and (111) oriented samples of single‐crystal SrTiO3 are used to study the effect of surface orientation on the oxygen surface exchange coefficient kO∗\[k_{\rm{O}}^*\] and the surface space‐charge potential Φ0. Isotope exchanges are carried out at temperatures 922 < T/K < 1073 at an oxygen activity aO2 = 0.2 in dry conditions (aH2O < 10−7.7); isotope profiles are measured subsequently by secondary ion mass spectrometry. Isothermal kO∗$k_{\rm{O}}^*$ values are found to vary by less than one order of magnitude, with kO∗false(111false)≈kO∗false(110false)>kO∗false(100false)$k_{\rm{O}}^*(111) \approx k_{\rm{O}}^*(110){\bm{ > }}k_{\rm{O}}^*(100)$. All kO∗$k_{\rm{O}}^*$ data are consistent with a change in the activation enthalpy of surface exchange from 3.0 eV at high temperatures to 1.8 eV at lower temperatures. The transition is attributed to a change from a charge‐transfer mechanism at high temperatures to a mechanism involving surface OH species. The transition temperature depends on the surface orientation, Ttr(111) ≈ Ttr(110) > Ttr(100). Values of Φ0 obtained varied between 0.50 V and 0.37 V, with isothermal values obeying Φ0(111) ≈ Φ0(110) < Φ0(100). Φ0 data is analysed to obtain the OH− surface coverage for the low‐temperature regime. Similarities between the behavior of Φ0 and that of kO∗$k_{\rm{O}}^*$ are highlighted.

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Correlating Surface Crystal Orientation and Gas Kinetics in Perovskite Oxide Electrodes

Cited by 23 publications

References 57 publications

Pt current collectors artificially boosting praseodymium doped ceria oxygen surface exchange coefficients

Pt current collectors artificially boosting praseodymium doped ceria oxygen surface exchange coefficients

Strain‐Induced Orbital Contributions to Oxygen Electrocatalysis in Transition‐Metal Perovskites

Surface Space‐Charge Potential and Oxygen Surface Exchange Coefficient of SrTiO₃: The Effect of Surface Orientation

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Correlating Surface Crystal Orientation and Gas Kinetics in Perovskite Oxide Electrodes

Cited by 23 publications

References 57 publications

Pt current collectors artificially boosting praseodymium doped ceria oxygen surface exchange coefficients

Pt current collectors artificially boosting praseodymium doped ceria oxygen surface exchange coefficients

Strain‐Induced Orbital Contributions to Oxygen Electrocatalysis in Transition‐Metal Perovskites

Surface Space‐Charge Potential and Oxygen Surface Exchange Coefficient of SrTiO3: The Effect of Surface Orientation

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Surface Space‐Charge Potential and Oxygen Surface Exchange Coefficient of SrTiO₃: The Effect of Surface Orientation