High hydrogen selectivity Pd-Ni alloy film hydrogen sensor with hybrid organosilica membranes

Hydrogen sensors are very important for real-time detection of hydrogen leakage. In this study, a Pd-Ni film hydrogen sensor with high hydrogen response and selectivity was fabricated. A 1.3 µm-thick organosilica membrane was coated on the surface of Pd-Ni alloy film by sol-gel process and hot-coating method to fabricate a 1,2-bis(triethoxysilyl)methane (BTESM)-coated Pd-Ni film hydrogen sensor, which endows the sensor with superior H2 selectivity due to the molecular sieve property. And the gas sensing performance was tested at optimum operating temperature. The results show higher response is obtained in both N2 and air atmosphere by hybrid organosilica membrane modification on the Pd-Ni film sensor. Very importantly, the response of the sensor to hydrogen is greatly improved and well maintained in the presence of oxygen, although the response/recovery time increased. The organosilica membrane has high permeability to hydrogen with the kinetic dimater of 0.289 nm while effectively inhibits the permeation of relatively larger gas molecule such as oxygen (0.34 nm) and methanol (0.38 nm), resulting in excellent selectivity to H2. The mechanism of response and selectivity enhancement is explored.