Oxygen vacancy formation and migration in double perovskite Sr<sub>2</sub>CrMoO<sub>6</sub>: a first-principles study

Zhao, Shuai; Gao, Liguo; Chen, Lan; Pandey, Shyam S.; Hayase, Shuzi; Ma, Tingli

doi:10.1039/c6ra05581h

Cited by 14 publications

(5 citation statements)

References 47 publications

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“…To reveal the effect of Br-vacancy on the electronic property of Cs 2 AgBiBr 6 , we calculated the density of states (DOS) for pure and Br-vacancy Cs 2 AgBiBr 6 surface using the method of GGA-PBE. From Figure 8 , it can be deduced that the forming of Br-vacancy can move the Fermi level from VBM to near the CBM, which is consistent with previous work on studying the O-vacancy and Cl-vacancy [ 80 , 81 , 82 ]. As the peak introduced by defective states is sharp and separated from the relatively delocalized electrons in the conduction band, the exceeding electrons brought by vacancy are localized.…”

Section: Resultssupporting

confidence: 88%

Improving the Catalytic CO2 Reduction on Cs2AgBiBr6 by Halide Defect Engineering: A DFT Study

et al. 2021

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Pb-free double halide perovskites have drawn immense attention in the potential photocatalytic application, due to the regulatable bandgap energy and nontoxicity. Herein, we first present a study for CO2 conversion on Pb-free halide perovskite Cs2AgBiBr6 under state-of-the-art first-principles calculation with dispersion correction. Compared with the previous CsPbBr3, the cell parameter of Cs2AgBiBr6 underwent only a small decrease of 3.69%. By investigating the adsorption of CO, CO2, NO, NO2, and catalytic reduction of CO2, we found Cs2AgBiBr6 exhibits modest adsorption ability and unsatisfied potential determining step energy of 2.68 eV in catalysis. We adopted defect engineering (Cl doping, I doping and Br-vacancy) to regulate the adsorption and CO2 reduction behavior. It is found that CO2 molecule can be chemically and preferably adsorbed on Br-vacancy doped Cs2AgBiBr6 with a negative adsorption energy of −1.16 eV. Studying the CO2 reduction paths on pure and defect modified Cs2AgBiBr6, Br-vacancy is proved to play a critical role in decreasing the potential determining step energy to 1.25 eV. Finally, we probe into the electronic properties and demonstrate Br-vacancy will not obviously promote the process of catalysis deactivation, as there is no formation of deep-level electronic states acting as carrier recombination center. Our findings reveal the process of gas adsorption and CO2 reduction on novel Pb-free Cs2AgBiBr6, and propose a potential strategy to improve the efficiency of catalytic CO2 conversion towards practical implementation.

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Section: Resultssupporting

confidence: 88%

Improving the Catalytic CO2 Reduction on Cs2AgBiBr6 by Halide Defect Engineering: A DFT Study

et al. 2021

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“…The O 1s core level spectra are fitted corresponding to three types of oxygen peaks, lattice oxygen, chemisorbed oxygen, and physisorbed oxygen. − From Figure (c), it was observed that the intensity signal of chemisorbed oxygen is stronger than that of lattice oxygen. The presence of chemisorbed oxygen at the surface could be attributed to defect correlation with dopant concentration and lattice oxygen associated to the formation of oxygen vacancies. , Zhao et al reported that oxygen vacancy formation and migration in double perovskite can be useful as an anode for SOFCs. The calculated percentage factors of lattice oxygen and chemisorbed oxygen given in Table indicate that the amount of chemisorbed oxygen is increased with a decrease in lattice oxygen.…”

Section: Results and Discussionmentioning

confidence: 99%

“…The presence of chemisorbed oxygen at the surface could be attributed to defect correlation with dopant concentration and lattice oxygen associated to the formation of oxygen vacancies. 44,45 Zhao et al 46 reported that oxygen vacancy formation and migration in double perovskite can be useful as an anode for SOFCs. The calculated percentage factors of lattice oxygen and chemisorbed oxygen given in Table 2 indicate that the amount of chemisorbed oxygen is increased with a decrease in lattice oxygen.…”

Section: Resultsmentioning

confidence: 99%

Influence of Lanthanum Doping on Structural and Electrical/Electrochemical Properties of Double Perovskite Sr₂CoMoO₆ as Anode Materials for Intermediate-Temperature Solid Oxide Fuel Cells

Kumar

Jena

Patro

et al. 2019

ACS Appl. Mater. Interfaces

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Lanthanum (La3+)-doped double perovskites Sr2CoMoO6 (Sr2–x La x CoMoO6, 0.00 ≤ x ≤ 0.03) were synthesized via the citrate–nitrate autocombustion route. The Reitveld refinement analysis of X-ray diffraction reveals the tetragonal symmetry as the main phase with space group I4/m and also confirms the presence of some peaks corresponding to extra phase SrMoO4. The SEM micrograph images reflect that grains are in irregular shape and sizes for all samples. Average grain size gradually decreases with the increase of the SrMoO4 phase. The X-ray photoelectron spectroscopy (XPS) analysis confirms the presence of mixed valence states of Mo5+/Mo6+, Co2+/Co3+, and O-lattice/O-chemisorbed/O-physisorbed species. Coefficient of thermal expansion (CTE) analysis shows that the particular composition Sr1.97La0.03CoMoO6 has the lowest CTE value among the compositions studied. The electrical conductivity of Sr2CoMoO6 is enhanced effectively by doping La at Sr sites. The measured area-specific resistance (ASR) for the composition Sr1.97La0.03CoMoO6 (SLCM03) is found to be appreciably low, ∼0.053 Ohm cm–2 at 800 °C. The obtained highest electrical conductivity with the lowest activation energy and low ASR value for the composition Sr1.97La0.03CoMoO6 encompasses it as a promising candidate for anode material in the intermediate-temperature solid oxide fuel cell (IT-SOFC) application.

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“…On the other hand, Cr 3+ creates the positively charged oxygen vacancies (V •• O ). The ionic radii of Cr 3+ and Mo 5+ valence states are identical, so there is a high probability of producing antisite defects, which are electron and oxygen vacancies (V •• O ) [27]. According to the Anderson model, the antisite defects in double perovskites might be generated due to octahedral disorder caused by the charge difference of B site cations (two or more).…”

Section: Discussionmentioning

confidence: 99%

“…It has been reported [27] that the bond between Cr-O is different from the Mo-O due to electron transfer between Cr cation and O ion, which is bridged by strong ionic bonds. SCM is an interesting material due to its potential applications in spintronics and magneto-transport devices [25,28].…”

Section: Introductionmentioning

confidence: 99%

Enhanced thermoelectric power factor led by isovalent substitution in Sr₂CrMoO₆ double perovskite

Saini¹,

Saxena²,

Bhattacharya³

et al. 2022

J. Phys. D: Appl. Phys.

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The strategy of using aliovalent substitution in A2B2O6 double perovskites remained the popular choice to enhance the charge carrier concentration in order to increase their electrical conductivity. In the present investigation, we have shown that the isovalent substitution in A-site can facilitate in manipulating the oxidation states of B-site transition metal cations in double perovskites, which in turn helps in increasing the carrier concentration. Further, using the strategy of manipulating valence states of B-site cations, we could enhance the thermoelectric power factor of double perovskites. Ceramic samples of BaxSr2-xCrMoO6 (x=0.0, 0.1, 0.2, and 0.3) double perovskites have been synthesized via solid-state reaction route. The phase constitution and morphological study have been carried out via XRD and FESEM. Rietveld refinement of XRD data confirms the polycrystalline cubic structure with Pm3-m space group. Negative values of Seebeck coefficient have been observed for these oxides in the temperature range from room temperature to 1100K, confirming electrons as the majority charge carriers. The electrical conductivity of Sr2CrMoO6 double perovskite is found to be increased by more than an order of magnitude due to isovalent Ba2+ doping in place of Sr2+. As a result, 5 times enhancement of thermoelectric power factor has been attained in BaxSr2-xCrMoO6. Charge transport mechanism of these double perovskites is found to be governed by the small polaron hopping conduction model. XPS spectra validates the presence of multivalent cations of Mo5+, Mo6+, Cr3+, and Cr6+ in theses double perovskites. Furthermore, the detailed defect chemistry analysis suggests that owing to Ba substitution, Cr is oxidized from Cr3+ to Cr6+ oxidationstates, which enhances the electron concentration and reduces the low mobility oxygen vacancies leading to dramatically improved electrical conductivity.

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Oxygen vacancy formation and migration in double perovskite Sr₂CrMoO₆: a first-principles study

Abstract: These calculations provided theoretical insight into the effect of the B-site Cr and Mo on the oxygen vacancy formation and migration in the double perovskite Sr2CrMoO6 using the DFT+U method.

Cited by 14 publications

References 47 publications

Improving the Catalytic CO2 Reduction on Cs2AgBiBr6 by Halide Defect Engineering: A DFT Study

Improving the Catalytic CO2 Reduction on Cs2AgBiBr6 by Halide Defect Engineering: A DFT Study

Influence of Lanthanum Doping on Structural and Electrical/Electrochemical Properties of Double Perovskite Sr₂CoMoO₆ as Anode Materials for Intermediate-Temperature Solid Oxide Fuel Cells

Enhanced thermoelectric power factor led by isovalent substitution in Sr₂CrMoO₆ double perovskite

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Oxygen vacancy formation and migration in double perovskite Sr2CrMoO6: a first-principles study

Abstract: These calculations provided theoretical insight into the effect of the B-site Cr and Mo on the oxygen vacancy formation and migration in the double perovskite Sr2CrMoO6 using the DFT+U method.

Cited by 14 publications

References 47 publications

Improving the Catalytic CO2 Reduction on Cs2AgBiBr6 by Halide Defect Engineering: A DFT Study

Improving the Catalytic CO2 Reduction on Cs2AgBiBr6 by Halide Defect Engineering: A DFT Study

Influence of Lanthanum Doping on Structural and Electrical/Electrochemical Properties of Double Perovskite Sr2CoMoO6 as Anode Materials for Intermediate-Temperature Solid Oxide Fuel Cells

Enhanced thermoelectric power factor led by isovalent substitution in Sr2CrMoO6 double perovskite

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Oxygen vacancy formation and migration in double perovskite Sr₂CrMoO₆: a first-principles study

Influence of Lanthanum Doping on Structural and Electrical/Electrochemical Properties of Double Perovskite Sr₂CoMoO₆ as Anode Materials for Intermediate-Temperature Solid Oxide Fuel Cells

Enhanced thermoelectric power factor led by isovalent substitution in Sr₂CrMoO₆ double perovskite