High performance potentiometric hydrogen sensor based on ZnO porous cage sensing electrode

In this paper, ZnO porous cages were prepared by a facile one-pot encapsulation-calcination method and used as sensing electrodes for planar mixed-potential hydrogen sensors. As the amount of cetyltrimethylammonium bromide (CTAB) added during the preparation increased, the size of the individual ZnO cage decreased while the average pore size increased. The hydrogen sensing performance was enhanced with the increase of CTAB addition. At 0.35 wt% CTAB addition, the response value of the cages to 20 ppm hydrogen at 450 °C was −60.8 mV, which was 11.5 times higher than that of the conventional particles. A high response of −10.6 mV was obtained for 0.3 ppm hydrogen. Moreover, the response time to 500 ppm hydrogen was 26 s, which was 10.6 times shorter than that of the particles. Better selectivity and excellent repeatability were also achieved. Superior potentiometric hydrogen performance is mainly attributed to the highly porous sensing electrodes constructed from cages.