Optimizing Hydrogen Sensing Behavior by Controlling the Coverage in Pd Nanoparticle Films

The response of quantum-conductance-based hydrogen sensors fabricated by controllable deposition of closely spaced Pd nanoparticle films between interdigital electrodes was investigated. Three typical response regions with different conductance-hydrogen pressure correlations were observed. The response characteristics of the devices were found to depend strongly on the nanoparticle coverage. In the low H(2) pressure region, higher coverage gives higher sensitivity. In the high H(2) pressure region, quantitative sensing can only be realized with low nanoparticle coverage. Optimizing the coverage allows the attainment of highly sensitive hydrogen sensors with a very wide quantitative working range, extending far beyond the hydrogen pressure region associated with the alpha-to-beta phase transition of Pd.