Curtin-UQ Workshop on Nanostructured Electromaterials for Energy. Perovskite Materials for Energy Applications. Perovskite of ABO 3

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1 Curtin-UQ Workshop on Nanostructured Electromaterials for Energy Perovskite Materials for Energy Applications Jan. 2016, Perth, Australia Zongping Shao Department of Chemical Engineering, Curtin University, Australia Perovskite of ABO 3 Perovskite is a calcium titanium oxide mineral composed of calcium titanate, with the chemical formula CaTiO 3. The mineral was discovered in the Ural Mountains of Russia by Gustav Rose in 1839 and is named after Russian mineralogist Lev Perovski ( ). It lends its name to the class of compounds which have the same type of crystal structure as CaTiO 3 ( XII A 2+VI B 4+ X 2 3) known as the perovskite structure.(wikipedia ) 2 1

2 Elements in perovskites ABO 3 A A-site B B-site A/B A/B-site 3 Progress in application of perovskite in new energy Solar Cell Science, 338, , Nature, 501, , Science, 345, , Mixed ionic and electronic conducting membrane Nature Materials, 9, , Nature communication, 6:6824, Solid Oxide Fuel Cell Nature, 431, , Science, 312, , Science, 326, , Nature Materials, 12, , Oxygen Reduction/Evolution Reaction (ORR/OER) Nature Chemistry, 3, , Science, 334, , Science, 334, , Nature communication, 4:2439, ABO 3 Lithium-ion Battery/Super Capacitor Nature Materials, 13, ,

3 Chem. Soc. Rev Our Research Focus Solar Cell Solid Oxide Fuel Cell J. Power Sources: 2009 Prog. Mater. Sci Chem. Rev. 2013, Adv. Energy Mater, Lithium-ion battery Super capacitor Perovskite Ceramic oxygen permeating membranes RSC Adv, 2013 EES, 2012 Chem. Rev, Oxygen Reduction/Evolution Reaction Wastewater degradation 5 Development of perovskite-type materials LnBaCo 2 O 5+ SrSc x Co 1-x O 3- SrNb x Co 1-x O 3- Ba 1-x Sr x Co 0.8 Fe 0.2 O 3- Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3- Free volume of lattice (Ba 0.5 Sr 0.5 ) 1±x Co 0.8 Fe 0.2 O 3-δ δ Valence state of A/B-site ions Title in here Anion/cation stoichiometry Ionic size of A/B-site ions Title in here Metal oxygen Bond energy Title Crystal in here structure A-site doping B-site doping A/B-site codoping Cation deficiency O-site doping Tailoring ionic valence state 6 3

4 Solid oxide fuel cells 7 An energy conversion device Solid oxide fuel cells Features:high energy conversion efficiency, high power outputs, versatile fuel Demerits:difficult sealing, high cost, fast performance degradation Key:reducing the operating temperature of solid oxide fuel cells Air e - Cathode O 2- O 2- Electrolyte e - Anode Fuels H 2 O, CO 2 8 4

5 Example 1 Precise tailoring the perovskite phase structure through A-site cation deficiency to increase electrocatalytic activity for oxygen reduction reaction at elevated temperature 9 A-site cation deficient Sr 0.95 Nb 0.1 Co 0.9 O 3-δ Cubic Tetragonal SNC (Pm-3m) SNC0.95 (P4/mmm) ChemSusChem 2013, 6, 2249 Sr-deficient sample has improved oxygen vacancy concentration and electrical conductivity. 10 5

6 A-site cation deficient Sr 0.95 Nb 0.1 Co 0.9 O 3-δ Symmetrical cell performance Single cell performance ASRs reduced by 40-50% 1016 mw cm 500 ChemSusChem 2013, 6, Example 2 In-situ phase reaction to form a core-shell structured electrode with improved electrocatalytic activity and stability for oxygen reduction reaction at elevated temperature 12 6

7 3D core (SDC) shell (perovskite) electrode from infiltration and beneficial reactive sintering A 3D core shell architecture is fabricated from solution infiltration in combination with high-temperature reactive sintering. A stable porous Sm 0.2 Ce 0.8 O 1.9 scaffold as the core for bulk oxygen ion diffusion, and a connective Sm, Ce-doped SrCoO 3 perovskite film as the shell for efficient oxygen reduction reaction and partial current collection. J. Mater. Chem. A, 2014, 2, D core shell electrode from infiltration and beneficial reactive sintering Area specific resistances Performance stability at 700 o C 4h 112h 208h o C, Ea = kj mol o C, Ea = kj mol o C, Ea = kj mol o C, Ea = kj mol Power outputs from single cell 1800 Z" ( cm 2 ) Z' ( cm 2 ) Phase structure evolution Voltage (V) o C o C o C o C 550 o C Current density (ma cm -2 ) J. Mater. Chem. A, 2014, 2, Power density (mw cm -2 ) Relative intensity (a.u.) After 200 h test fresh ( o ) 14 7

8 Example 3 Perovskite as the host for creating regenerative nanoparticles to improve the electrocatalytic activity for oxygen reduction reaction at elevated temperature 15 Self-breathing cathodes decorated with nano-particles SrFe 0.85 Ti 0.1 Ni 0.05 O 3 Reduced by H 2 SrFe 0.7 Ti 0.3 O 3 -after-h 2 -Ar-800 o C-20 h SrFe 0.65 Ti 0.3 Ni 0.05 O 3 -after-h 2 -Ar-800 o C-20 h Relative Intensity (a.u.) SrFe 0.7 Ti 0.3 Ni 0.05 O 3 -after-h 2 -Ar-800 o C-20 h Ni ( o ) 16 8

9 Self-breathing cathodes decorated with nano-particles First 600 o C After dealing with H 2 -Ar 10 min lm Z ( cm 2 ) Hz 10 2 Hz 10 Hz 1 Hz 0.1 Hz Hz Re Z ( cm 2 ) ASR( cm 2 ) o C 200 h 600 o C 25 h 600 o C 0.05 After H 2 -Ar treated for 10 min 850 o C 50 h After H 2 -Ar treated for 10 min Times (h) 17 Perovskite anodes for solid oxide fuel cells The traditional anodes for SOFCs are Ni+YSZ and Ni+SDC, which suffered from serious coking and sulfur poisoning. The perovskite anodes or Ni+perovskite anodes could use gaseous and liquid hydrocarbons or oxygenated hydrocarbons directly. Advantages External reforming apparatus free. Using the extant public infrastructure for fuel storage and transportation directly. Challenges Coking resistance Sulfur tolerance 18 9

10 Example 4 Perovskite oxide as a water storing host to increase the coking resistance and sulfur tolerance of nickel anode 19 Ni+BaZr 0.4 Ce 0.4 Y 0.2 O 3 anodes with water storage capability Strategy: The storing water in the Ni+BaZr 0.4 Ce 0.4 Y 0.2 O 3 (BZCY) anode with water storage capability could react with the coke and sulfur, and then coke and sulfur could be eliminated. Environ. Sci. Technol. 2014, 48, ChemSusChem 2014, 7,

11 Enhanced coking resistance of Ni+BZCY anode FTIR Ethanol to steam ratio of 1:1 Ni+BZCY displays a much higher water storage capability than the Ni+SDC anode. When ethanol-steam (1:1) is used as the fuel, Ni+BZCY shows superior coking resistance than traditional Ni+YSZ and Ni+SDC anodes. The Ni+BZCY anode prepared by GNP also displays a higher coking resistance than that prepared by PM. ChemSusChem 2014, 7, Environ. Sci. Technol. 2014, 48, Enhanced coking resistance of Ni+BZCY anode 600 o C 600 o C Ethanol to steam ratio of 1:1 Ethanol to steam ratio of 1:1 The cell with Ni+BZCY anode displays an excellent stability for 180 h without any sign of voltage decay. However, the fuel cells with the traditional Ni+SDC and Ni+YSZ anodes are only run for around 1 2 h under the same conditions. ChemSusChem 2014, 7,

12 Improved sulfur tolerance of Ni+BZCY anode Ni+SDC Ni+BZCY With the increase of the H 2 S content in the fuel, the cell with Ni+SDC degrades rapidly while no obvious performance drop is observed with Ni+BZCY anode expect for 1000 ppm H 2 S-H 2 fuel. Environ. Sci. Technol. 2014, 48, Improved sulfur tolerance of Ni+BZCY anode For the cell with Ni+SDC anode, the voltage is not stable and the cell is failed after a continuous operation for 150 minutes under a current density of 200 ma cm -2 at 600 o C. In contrast, the cell operation is stable for 700 minutes when Ni+BZCY anode is applied. Environ. Sci. Technol. 2014, 48,

13 H + -SOFC According to the type of electrolytes, SOFC can be classified as H + -SOFC and O 2- -SOFC O 2- -SOFC H + -SOFC Merits of H + -SOFC Low ion conducting activation energy Relative low operating temperature The fuel in anode chamber will not be diluted during operation 25 Example 5 Exsolved nanoparticles from perovskite proton conductors to improve sintering and conductivity of perovskite proton conductors 26 13

14 Electrolyte: BaCe 0.8 Y 0.1 Pd 0.1 O 3-δ (BCYPd) Pd nano-particles appear on BCYPd surface after high temperature thermal reduction. 27 Electrolyte: BaCe 0.8 Y 0.1 Pd 0.1 O 3-δ Pd nano-particles can promote the sintering of BCYPd and the formed B-site deficient BCYPd has higher ionic conductivity. 645 mw cm -2 Conductivity reach S cm -1 at 500 o C 28 14

15 Perovskite-type metal oxides for catalyzing oxygen reduction/evolution reaction 29 Oxygen reduction/evolution reaction(orr/oer) ORR ORR O H e Cat. 2 H 2 O O 2 + 2H 2 O + 4e 4OH Cat. OER OER O 2 + H + + e HOO* O 2 + H 2 O + e HOO* + OH O R R HOO* + H + + e O* + H 2 O O* + H + + e HO* HO* + H + + e H 2 O O E R O R R HOO* + e O* + OH O* + H 2 O+ e HO* + OH HO* + e OH O E R acid medium alkaline medium Recent studies mainly focused on catalysts for ORR/OER in alkaline medium

16 Selection of catalysts A classical Demerits Demerits benchmark catalyst High costs & for ORR: Pt/C Low stability Classical benchmark catalysts for OER : IrO 2 and RuO 2 Replace precious metal Organic metal carbon-based : M-N x Nobel metal materials free Composite materials carbide nitride Metal oxide sulfide 31 Perovskite-type metal oxides Noble metal-free oxides Simple metal oxides: (Co, Fe, Mn, Ni)O x Perovskite-type metal oxides: ABO 3 Spinel-type metal oxides: (Co, Fe, Mn, Ni) 3 O 4 Merits of Perovskite-type metal oxides: Low costs Easy tailoring of properties through ion-doping Ideal crystal structure of ABO 3 A: lanthanide or alkaline-earth metal elements B: transition metal elements C: Oxygen 32 16

17 Example 6 Perovskite oxides for efficient oxygen evolution reaction at alkaline medium at room temperature 33 SrNb 0.1 Co 0.7 Fe 0.2 O 3-δ catalyst for OER Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ : high intrinsic activity, but inferior stability Developing high performance noble metal-free catalysts with long-term stability for OER Nb-doped SrNb 0.1 Co 0.7 Fe 0.2 O 3-δ (SNCF) Y. L. Zhu, Z.P. Shao et al., Angew. Chem. Int. Ed., 2015, 54,

18 SrNb 0.1 Co 0.7 Fe 0.2 O 3-δ catalyst for OER Tetragonal system with space group of P 4/mmm Y. L. Zhu, et al., Angew. Chem. Int. Ed., 2015, 54, SrNb 0.1 Co 0.7 Fe 0.2 O 3-δ catalyst for OER Activity Stability Intrinsic activity: SNCF>BSCF>IrO 2 Good performance stability Y. L. Zhu, et al., Angew. Chem. Int. Ed., 2015, 54,

19 SrNb 0.1 Co 0.7 Fe 0.2 O 3-δ catalyst for OER (a) XPS (b) EIS Optimized electronic band structure (e g =1.2) Good electronic conducting ability High OH - adsorption ability High O 2 desorption ability (c) FTIR (d) O 2 -TPD Y. L. Zhu, et al., Angew. Chem. Int. Ed., 2015, 54, BaCo 0.9-x Fe x Sn 0.1 O 3-δ catalyst for OER Doping of A- or B-site cations in the perovskite structure has been reported to be an effective way to enhance OER catalysis. Cobalt-based perovskites generally have superior OER catalytic activity Co-doping BaCoO 3-δ parent oxide with iron and tin for highly efficient OER electrocatalysis BaCo 0.9-x Fe x Sn 0.1 O 3-δ (BCFSn) Tunable OER catalytic activity synergistic effect X. M. Xu, et al., Adv. Sci., 2015, doi: /advs

20 BaCo 0.9-x Fe x Sn 0.1 O 3-δ catalyst for OER Space group: Pm-3m Oxides Nonstoichiometries (δ) Surface areas (m2/g) Co oxidation states a) BCFSn (1) 0.79 ~ +3.0 b) BCFSn (4) 0.90 ~ +3.0 c) BCFSn (6) 0.80 ~ +3.0 X. M. Xu, et al., Adv. Sci., 2015, doi: /advs BaCo 0.9-x Fe x Sn 0.1 O 3-δ catalyst for OER Catalysts Onset (V vs RHE) Tafel slope (mv/dec) BCFSn-541 ~ ±2 BCFSn-631 ~ ±2 BCFSn-721 ~ ±1 IrO 2 (benchmark) ~ ±1 Tunable OER activity: BCFSn-541 < BCFSn-631 < BCFSn-721 X. M. Xu, et al., Adv. Sci., 2015, doi: /advs Onset potential and Tafel slope of BCFSn are comparable with those of benchmark IrO

21 BaCo 0.9-x Fe x Sn 0.1 O 3-δ catalyst for OER (a) FTIR (b) Metal-oxygen bond energy (e) Electrical conductivity (c) O 2 -TPD (d) EIS X. M. Xu, et al., Adv. Sci., 2015, doi: /advs Good electronic conducting ability High OH - adsorption ability High O 2 desorption ability Low metal-oxygen bond energy High electrical conductivity at room temperature BCFSn-721 with highest catalytic activity 41 BaCo 0.9-x Fe x Sn 0.1 O 3-δ catalyst for OER Codope Stable cubic structure Synergistic effect Higher OER catalytic acitivity and performance stability are observed from BCFSn-721 as compared with those of BaCoO 3-δ matrix and single element doped BaCo 0.7 Fe 0.3 O 3-δ (BCF) and BaCo 0.7 Sn 0.3 O 3-δ (BCSn). X. M. Xu, et al., Adv. Sci., 2015, doi: /advs

22 Example 6 Perovskite oxide lattice for stabilizing unusual high valence state of some elements to result in improved electrocatalytic activity for oxygen reduction reaction 43 LaFe 0.95 Pd 0.05 O 3 catalyst for ORR Classical ORR catalyst of Pt/C: High cost, low stability Pd-based ORR catalysts: alloy, morphology optimization little information is available about the effect of the oxidation state of Pd on ORR activity: the difficulty in manipulating the oxidation state to a higher level for Pd (e.g., 3/4+). stabilizing its unusual high oxidation states via doping the Pd into a perovskite oxide Lattice: LaFe 0.95 Pd 0.05 O 3 (LFP) Y. L. Zhu, et al., Chem. Mater., 2015, 27, 3048 Pd 0, Pd 2+, perovskite-type ionic (Pi) Pd n+ (n>2) 44 22

23 LaFe 0.95 Pd 0.05 O 3 catalyst for ORR ORR catalytic activity: perovskite-type ionic (Pi) Pd 3/4+ > Pd 2+ > Pd 0 Y. L. Zhu, et al., Chem. Mater., 2015, 27, LaFe 0.95 Pd 0.05 O 3 catalyst for ORR LFP: higher mass activity, superior performance stability, good resistance to methanol poisoning Y. L. Zhu, et al., Chem. Mater., 2015, 27,

24 LaFe 0.95 Pd 0.05 O 3 catalyst for ORR Band structure d-band center Ideal band structure: e g =1 Lowered-band center Y. L. Zhu, et al., Chem. Mater., 2015, 27, Example 7 Perovskite-type metal oxides for supercapacitor 48 24

25 LaMnO 3±δ Supercapacitor The cubic structure of LaMnO 3 At a sufficiently low scan rates (10mV/s), the specific capacitances of oxygen-excess and oxygen-deficit LaMnO 3±δ reach F/g, F/g, respectively. Mechanism of oxygen intercalation into LaMnO 3±δ Initially oxygen vacancies are filled through intercalation of an electrolyte oxygen ion and diffusion of O 2- along octahedral edges through the crystal concomitant with the oxidation of two Mn 2+ centers to two Mn 3+. In the next step of the reaction, excess oxygen is intercalated at the surface through diffusion of manganese to the surface and oxidation of two Mn 3+ centers to two Mn 4+. J. Tyler Mefford, Nature Material, 2014, 13, Application of other perovskite oxides in supercapacitor 233 F/g BSCF Co 3 O F/g 464F/g 503 F/g BSCF SrCoO 3 The symmetrical GCD rate test manifests that the capacitance of BSCF is mainly originate from the surface pseudo capacitance. BSCF has higher specific capacitance than that of Co 3 O 4, and can store more than 2 times of energy

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