A limiting current hydrogen sensor based on BaHf0.8Fe0.2O3-δ dense diffusion barrier and BaHf0.7Sn0.1In0.2O3-δ protonic conductor

A limiting current hydrogen sensor was successfully prepared by the co-pressing and co-sintering method using proton-electron mixed conductor BaHf 0.8 Fe 0.2 O 3-δ as the dense diffusion barrier instead for small hole and BaHf 0.7 Sn 0.1 In 0.2 O 3-δ as proton conducting electrolyte. The BaHf 0.8 Fe 0.2 O 3-δ and BaHf 0.7 Sn 0.1 In 0.2 O 3-δ powders were synthesized by high temperature solid state method. The phase composition, microstructure, chemical stability and conductivity of materials were characterized. Sensing performance of the hydrogen sensor was tested. The results show that dense BaHf 0.8 Fe 0.2 O 3-δ and BaHf 0.7 Sn 0.1 In 0.2 O 3-δ layer are closely combined together by the co-pressing and co-sintering technique at 1600 °C for 8 h and clear boundaries are observed between two pure perovskite phases. BaHf 0.8 Fe 0.2 O 3-δ shows excellent chemical stability for pure H 2 and CO 2 , water steam and 200 ppm H 2 S/Ar. Meanwhile, as the dense diffusion barrier, BaHf 0.8 Fe 0.2 O 3-δ possesses considerable proton and electron conductivity compared with small hole. The sensor shows a stable limiting current platform in 0–600 ppm H 2 at 400–600 °C at a certain voltage range due to dense BaHf 0.8 Fe 0.2 O 3-δ layer forming diffusion control. The limiting current (ΔI L ) has a good linear dependence on the hydrogen concentration. In addition, there is a good linear relationship between log(I L T) and 1000/T, and the Arrhenius model of limiting current is log(I L T) = 6.21-4.96 × 1000/T, and the hydrogen diffusion activation energy is 0.98 eV. The sensor has good long-term stability and high anti-interference capability to O 2 , CO 2 or H 2 S, but water vapor has a certain effect on sensing performance.