Hexagonal boron nitride auxiliary electrode for YSZ based hydrogen sensor

Potentiometric sensors aiming at detecting H2 were examined. Yttria-stabilized zirconia (YSZ) based sensor elements, H2, Pt/YSZ/Pt, air, responded to a ppm level of H2 contamination in air with the value of electromotive force (ΔEMF) = 30 mV at 350 °C. Coating the Pt sensing electrode with a powder of hexagonal boron nitride (h-BN) increased the EMF response, and the sensor response further increased by the milling treatment of the h-BN powder in ethanol. However milling treatment over 24 h reversed the response to decreasing. The specific surface area of the h-BN powder monotonously increased by the ball-milling which induced exfoliation of the BN layer. While Fourier transform infrared spectroscopy analysis suggested that point defects existing in the BN plane react with ethanol or water by the milling for >48 h. It was concluded that the point defects in h-BN play a decisive role in the property of the h-BN auxiliary phase in sensor response to H2.