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+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　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　ΔI　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.　©　2018　Elsevier　Ltd