Electrodeposition of Pd-Ag Alloy Nanoparticle Chains on Carbon Fibers and Their Hydrogen Sensing Properties

Pd-Ag alloy nanoparticle chains were fabricated on carbon fibers using three-pulse electrodeposition method. Pd-Ag alloy nanoparticle chains on carbon fiber surfaces can be used as hydrogen sensors. Scanning electron microscopy (SEM) andX-ray spectroscopy (EDX) were used to characterize the morphology and composition of the alloy nanoparticle chains. A CHI660B electrochemical workstation was used to evaluate the hydrogen sensing ability. Results show that Pd-Ag alloy nanoparticle chain arrays with a silver content of 16.0%-25.0%(w) were obtained in the electrolyte with an ion concentration ratio (molar ratio) of palladium to silver of 15:1. At -1.0 - -1.5 V nucleation took place within 5-40 ms and at -0.25 - -0.35 V growth was allowed for 200-300 s. The sensors responded to hydrogen gas at concentrations of 0.30%-5.00% (φ, volume fraction) at roomtemperature. The fastest response time was about 300 s and 31.0% sensitivity was obtained. The response current was linearly proportional to the hydrogen concentrations from 0.30% to 1.20%(φ). The current signal did not change with the hydrogen concentration larger than 4.00%. These hydrogen sensors show good reproducibility at hydrogen concentrations lower than 3.50%.