Ultra-sensitive hydrogen gas sensors based on Pd-decorated tin dioxide nanostructures: Room temperature operating sensors

We have investigated the fabrication of hydrogen gas sensors based on networks of Pd nanoparticles (NPs) deposited tin dioxide nanowires (NWs). SnO2 NWs with tin NPs attached on the surface were obtained by a simple thermal evaporation of SnO crystalline powders. The tin dioxide NWs were decorated with Pd NPs by the reduction process in Pd ion solution. The sensors showed ultra-high sensitivity (∼1.2 × 105%) and fast response time (∼2 s) upon exposure to 10,000 ppm H2 at room temperature. These sensors were also found to enable a significant electrical conductance modulation upon exposure to extremely low concentrations (40 ppm) of H2 in the air. Our fabrication method of sensors combining with Pd NPs, Sn NPs and n-type semiconducting SnO2 NWs allows optimized catalytic and depletion effect and results the production of highly-sensitive H2 sensors that exhibit a broad dynamic detection range, fast response times, and an ultra-low detection limit.