Application of layered perovskite type proton conducting KCa2Nb3O10 in H2 sensors: Pt particle size and temperature dependence

An all-solid-state ceramic hydrogen sensor working under short circuit amperometric conditions at low temperature has been developed. Ambient air was used as reference. The Dion-Jacobson (D-J) type layered perovskite KCa2Nb3O10 has been employed as electrolyte, studying the sensing response to 1–8% H2 concentrations in air. Thin films of platinum electrodes were deposited on the layered perovskite structured electrolyte by the multistep-impregnation-reduction (M-I-R) method. The electrochemically active particle size of 300–500 nm was optimised by control of the reductant concentration. Electrodes with high porosities and Pt loading of 1.85 mg cm−2 were obtained. The device was operated between 25 and 65 °C. The response time was in the range of 8–15 s and a stable current output was observed. The sensors were capable of detecting H2 with high reproducibility at 45 °C with a maximum sensitivity of 11.7 μA cm−2 %−1. The structural and micro-structural characterizations were carried out with XRD and SEM, respectively.