Engineering oxygen vacancy to accelerate proton conduction in Y-doped BaZrO3. (1st May 2023)

• Record Type: Journal Article
• Authors: Zhu, Kang; Shi, Nai; Zhang, Lijie; Huan, Daoming; Li, Xinyu; Zhang, Xiaoyu; Song, Rui; Xia, Changrong; Peng, Ranran; Lu, Yalin
• Is Part Of: Ceramics international. Volume 49(2023)Part A
• Page Start: 13321
• Page End: 13329
• Publication Date: 2023-05-01
• Subjects: Proton conducting solid oxide cells -- Proton conducting perovskite oxides -- Proton conductivity -- Oxygen vacancy engineering -- Density functional theory -- Ab initio molecular dynamics; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2022.12.206
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: Proton conducting oxides have drawn great interest as electrolytes for proton-conducting reversible solid oxide cells (P-RSOCs), but suffered from the inferior ionic conductivity. To accelerate proton conduction, oxygen vacancy engineering via calcium-doping is proposed and validated, which generates more oxygen vacancies to increase proton concentration and importantly tailors the position of oxygen vacancy to accelerate proton diffusion. TG and EIS results show that calcium-doped BaZr0.8 Y0.2 O3-δ (BZY2), BaZr0.8 Ca0.1 Y0.2 O3-δ (BZCa1Y2), owns higher proton concentration, and demonstrates ionic conductivity of 0.008 S cm −2 at 700 °C, 2.7 times higher than BZY2. The lower activation energy of conductivity in BZCa1Y2 confirms the faster proton conduction behaviour. DFT calculation concludes that oxygen vacancies prefer to cluster with Ca site and proton diffusion barrier is decreased most when vacancy is tailored to generate nearing Ca. When considering the concentration of proton and oxygen vacancy, proton diffusion coefficient obtained from Ab-initio Molecular Dynamics simulation is 1.1 × 10 −5 cm 2 s −1 for BZCa1Y2 in 200 °C, larger than BZY2 (9.0 × 10 −6 cm 2 s −1 ) and verifying the accelerated proton diffusion due to the tailored oxygen vacancy. The oxygen vacancy engineering provides a further understanding of proton diffusion in proton conducting oxides and a new promising opportunity to improve conductivity. Graphical abstract: Oxygen vacancy engineering aroused by Ca 2+ doping increases proton concentration by increasing oxygen vacancy concentration, and the tailored position of oxygen vacancy, accelerates proton diffusion, thus the total conductivity increases 2.7 times comparing with undoped electrolyte. Image 1