| At present, the techinique of electrodeposition by template synthesis is the representative method for fabricating nanomaterials, such as nanowires, nanotubes, nanrodes, etc.. Palladium alloy composed of 8～15% nickel or 16～25% silver can increase its dynamic reversibility of absorbing hydrogen and prevent the alloy from hydrogen damnification. So Pd-Ni and Pd-Ag alloy nanowires are more promising materials which is used to fabricate practical hydrogen sensors. Our work focuses on using electrodepostion technique to fabricate Pd-alloy nanowires into the nanopores of porous anodic aluminum oxide template. The fabrication of Pd-Ni and Pd-Ag alloy nanowire arrays is investigated by alternating current (AC) and direct current (DC). Morphologies, compositions and crystal structures of the palladium alloy nanowires were characterized by SEM, EDX and XRD. The main results are gained as following:1. When 50 Hz AC source of 5 V, 10 V, 15V is used to elctrodeposit Pd-Ni alloy nanowires, Pd-Ni alloy nanowires with 0%, 12.15% and 25.37% nickel contents and Pd-Ag alloy nanowires with 42.25%, 35.74% and 18.86% silver contents can be obtained, repectively. The SEM images show that the diameter of nanowire is agreed with the diameter of template and the nanowores with the length of 20μm and the aspect ratio of 200 can be fabricated, but the nanowires display discontinuous strips.2. When Pd-Ni alloy nanowires are fabricated in the pH 8.5 electrolyte of 60 mmol·dm-3 Pd(NH3)4Cl2+ 40 mmol·dm-3 NiSO4-6H2O+ 0.2 mol·dm-3 NH4Cl by constant DC potential of-0.6 V, Pd-Ni alloy nanowires with 11.89% nickel content can be obtained; In the pH 8.5 electrolyte composed of 70 mmol·dm-3 Pd(NH3)4Cl2+ 30 mmol·dm-3 NiSO4-6H2O+ 0.2 mol·dm-3 NH4Cl, 9.57% and 12.76% nickel contents in Pd-Ni alloy nanowires can be obtained by applying-0.6 V and-0.8V, respectively. In the pH 8.0 electrolyte composed of 15 mmol·dm-3 Pd(NO3)2+1.0 mmol·dm-3 AgNO3 +0.5 mol·dm-3 NH4NO3, Pd-Ag alloy nanowires with 23.73% and 17.28% silver content can be obtained by applying-0.8 V and-1.0 V; In the pH 8.0 electrolyte of 20 mmol·dm-3 Pd(NO3)2+1.0 mmol·dm-3 AgNO3 +0.5 mol·dm-3 NH4NO3, Pd-Ag alloy nanowires with 17.69% silver content can be obtained by applying-0.8V.3. When Pd-Ni alloy nanowires are fabricated in the pH 8.5 electrolyte composed of 70 mmol·dm-3 Pd(NH3)4Cl2+ 30 mmol·dm-3 NiSO4·6H2O+ 0.2 mol·dm-3 NH4C1 by galvanostatic electrodeposition of current density 0.8 mA·cm-2, the composition of nanowires obtained is 10.47% nickel content. In the pH 8.0 electrolyte of 20 mmol·dm-3 Pd(NO3)2+10 mmol·dm-3 AgNO3 +0.5 mol·dm-3 NH4NO3, Pd-Ag alloy nanowires with 19.81% silver content are obtained by applying 2.5 mA·cm-2.4. The images of SEM show that Pd-alloy nanowire arrays can be obtained by both potentionstatic and galvanostatic electrodeposition, but more continuous nanowires with the diameter of 200 nm, the length of 50μm and the aspect ratio of 250 are fabricated using galvanostatic electrodeposition.5. The results of XRD analysis show that Pd-Ni and Pd-Ag alloy exist in main form of <111> crystal phase structure and there are still some other phases such as <200> <220> <222>. High alloy structure exists in the Pd-Ni and Pd-Ag crystal.6. The Pd-Ni alloy nanowire arrays are used to assemble simple sensor and to research its kinetics of hydrogen adsorption. The responding currents detected are 4.21μA, 4.26μA, 4.35μA, 4.44μA, 4.50μA at hydrogen concentration 1.0%, 2.5%, 5.0%, 7.5%, 10.0%, respectively. The equations of responding current with hydrogen concentration for Pd-Ni nanowires can express asFor Pd-Ag alloy nanowires, the responding currents changes from 3.01μA, 3.52μA, 4.02μA, 4.62μA, 5.96μA at the hydrogen concentration of 1.0%, 2.5%,.5.0%, 7.5%, 10.0%, respectively. There is a equation of responding current relating to hydrogen concentration, which can be expressed asThe migratory process of atomic hydrogen in Pd-alloy nanowires is the mechanism of dissolution-diffusion and association-solubility-diffusion. The Pd-alloy nanowires will expand after adsorbing hydrogen and their resistance will be reduced.
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