The work proposed a distinct arrangement to construct the amperometric-type NO2 sensor using pyrochlore-phase Pr2Zr2O7 as oxygen-defect conductor. An effective co-doping strategy at A and B sites was explored to prepare the defective Pr2-xMxZr1.95In0.05O7+delta (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 Ca2+ doping at A site can be inclined to 8b oxygen defects, as opposed to Sr2+ and Ba2+ incorporation that can cause migratable 48f oxygen defects. DFT simulation indicates that the thermally excited electrons for the Ca2+ doping are uneasier to enter the conduction band through two deeper impurity levels, compared to Sr2+ and Ba2+ 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 Delta 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 Pr2Zr2O7 and commercial YSZ sensors, respectively, exhibiting the potential industrial application prospect. (c) 2018 Elsevier Ltd. All rights reserved.