Nanostructures of Pd–Ni alloy deposited on carbon fibers for sensing hydrogen

• Fabricated nanofilm and nanoparticles of Pd–Ni alloy.
• Assembled the two nanostructures for hydrogen sensors.
• Demonstrated performance of the two nanosensors.
• Discussed mechanism of sensing hydrogen.

Pd–Ni alloy nanofilm and nanoparticles with various sizes have been electrodeposited on carbon fibers through controlling potential pulses. The two types of Pd–Ni alloy nanostructures can be used to detect hydrogen gas at room temperature. The dependence of H2 sensing behavior on sizes of the nanofilm and nanoparticle has been discussed. The results show that response time decreases with hydrogen concentration increasing. In the two ranges of 0–2.8% and 3.6–6% H2 gas surroundings, response of nanofilm increases with hydrogen concentration, but slightly decreases after exposure to 2.8–3.6% H2 due to rearrangement of the particles in the nanofilm sensor. For nanoparticles sensor, response increases with hydrogen concentration between 0% and 6%. Both of them display good stability and reversibility. H2 sensing by the Pd–Ni alloy nanostructures depends on the synthesis of volume expansion of the particles or film, the change of energy barrier at the interface and formation of Pd–H in H2 gas. The recovery time is shorter in air due to the presence of oxygen than in pure argon.