Concentration-specific hydrogen sensing behavior in monosized Pd nanoparticle layers.

In this study, H2 sensing behavior of monosized and monocrystalline Pd nanoparticles has been studied as a function of H2 concentration and measurement temperature. A unique concentration-specific H2 sensing behavior with a 'pulsed' response at larger H2 concentrations and 'saturated' response at lower concentrations has been observed. The threshold concentration required for transition from 'saturated' to 'pulsed' response is very sensitive to measurement temperature. The characteristic change in the sensing behavior can be used to develop a novel sensor capable of determining H2 concentration level having high sensitivity and fast response. This study demonstrates that electrical and gas sensing properties of the nanoparticle layer depend critically on interparticle gaps.