Pyrochlore Pr2Zr1.95In0.05O7+δ oxygen conductors: Defect-induced electron transport and enhanced NO2 sensing performances. (10th January 2019)

• Record Type: Journal Article
• Authors: Zhong, Fulan; Zhao, Jiwu; Shi, Lanqian; Cai, Guohui; Zheng, Yong; Zheng, Ying; Xiao, Yihong; Jiang, Lilong
• Is Part Of: Electrochimica acta. Volume 293(2019)
• Page Start: 338
• Page End: 347
• Publication Date: 2019-01-10
• Subjects: NO2 sensor -- Pyrochlore-phase oxides -- Band structure -- Oxygen-defect -- Dark current; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2018.09.152
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: The work proposed a distinct arrangement to construct the amperometric-type NO2 sensor using pyrochlore-phase Pr2 Zr2 O7 as oxygen-defect conductor. An effective co-doping strategy at A and B sites was explored to prepare the defective Pr2-x Mx Zr1.95 In0.05 O7+δ (PMZI, M = Ca, Sr, Ba) oxygen conductors. DFT results show that the band structure of solid electrolyte are dependent of the doping elements at A and B sites. A-site doping theoretically causes 48f and 8b oxygen defects, yet only 48f oxygen defect for B-site doping. Oxygen defect energy shows that Ca 2+ doping at A site can be inclined to 8b oxygen defects, as opposed to Sr 2+ and Ba 2+ incorporation that can cause migratable 48f oxygen defects. DFT simulation indicates that the thermally excited electrons for the Ca 2+ doping are uneasier to enter the conduction band through two deeper impurity levels, compared to Sr 2+ and Ba 2+ doping, as the dark current is lower for the PCZI sensors. The oxygen-defect induces both the electron transport and enhanced NO2 sensing performances. The result of amperometric response obviously exhibits that the Δ I value of the optimized PCZI (0.02) sensor with high sensitivity (224 nA/ppm) is 15.11 and 12.26 times as high as the pure Pr2 Zr2 O7 and commercial YSZ sensors, respectively, exhibiting the potential industrial application prospect. Highlights: Elaborating oxygen-defect sites caused by doping through theoretical calculation. Alkaline earth metal ion serves as a dopant in view of its dual function. Oxygen-defect induces the electron transport and enhanced NO2 sensing performances. Constructing the relationship between the dark current and band structure by DFT.