A novel amperometric hydrogen sensor based on nano-structured ZnO sensing electrode and CaZr0.9In0.1O3−δ electrolyte

An amperometric hydrogen sensor using nano-structured ZnO as sensing electrode (SE) and CaZr0.9In0.1O3−δ a proton conductor as electrolyte was fabricated. A bilayer CaZr0.9In0.1O3−δ electrolyte including both a dense layer and a porous layer was prepared by conventional solid state reaction method. During the preparation of electrolyte, sintering aid (ZnO) was introduced into CaZr0.9In0.1O3−δ for promoting its sintering. The ZnO-SE particles were in situ prepared in the porous CaZr0.9In0.1O3−δ backbone by impregnating method. The composition and microstructure of the sensor were characterized by XRD and SEM, respectively. The properties of the sensor for monitoring hydrogen were studied. The results showed that a dense CaZr0.9In0.1O3−δ electrolyte with good stability was prepared at 1350 °C. The ZnO-SE particles with diameters of 200 nm were homogeneously dispersed in the porous CaZr0.9In0.1O3−δ backbone. The response current of the sensor was almost linear to H2 concentration in the range of 50-500 ppm. With the temperature increasing, the sensitivity increased and reached 179.87 nA/ppm at 700 °C. The sensor showed fast response/recovery, good reproducibility, and stability.