Sensing properties of resistive-type hydrogen sensors with a Pd-SiO2 thin-film mixture

Zigzag-shaped pure-Pd thin film and Pd-SiO2 thin-film mixture as resistive-type hydrogen sensors were deposited on cover-glass substrates through a multiple-boat thermal evaporator. Temperature dependence of the resistance of the pure-Pd resistive-type sensor showed a relative sensitivity of 3.2% at 80 degrees C with a temperature coefficient of the resistance (TCR) of 0.058%/degrees C. Sensing properties of the Pd-SiO2 resistive-type sensor responding to the presence of 1% H-2/N-2 are much better than those of the pure-Pd one, including a higher relative sensitivity (9%-7.7%), a faster response time (10 s-30 s), and a lower detection concentration limit (50 ppm-100 ppm). A higher dissociation rate and a faster diffusion rate due to porous-like properties and more hydrogen atoms caught due to oxygen associated with the Pd-SiO2 thin-film mixture explain why the Pd-SiO2 resistive-type sensor has a higher relative sensitivity with a shorter response time. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.