Release Time:2019-10-22  Hits:

Indexed by: Journal Article

Date of Publication: 2015-04-01

Journal: CHEMPLUSCHEM

Included Journals: SCIE

Volume: 80

Issue: 4

Page Number: 722-730

ISSN: 2192-6506

Key Words: alloys; hydrogen; nanostructures; palladium; sensors

Abstract: Understanding how the detailed nanoscale structure governs the interfacial interactions and reactivities is key to the exploration of nanostructured chemical sensors. We describe herein novel findings of an investigation of a palladium-gold alloy nanowire interface for hydrogen sensing. A dielectrophoretic growth pathway was utilized for controllable fabrication of the alloyed nanowires with minimum branching structures on a microelectrode device using controlled ratios of palladium and gold precursors in a two-step mechanism, a nucleation process initiated at a lower alternating current (AC) frequency followed by a growth process at a higher frequency up to 15MHz. The nanowires showed a reduced branching propensity and highly oriented 1D feature, with the bimetallic composition scaling linearly with the frequency. The nanowires exhibited excellent responses to hydrogen in concentrations as low as 0.5% by volume. The hydrogen-response characteristic represents an optimized balance of the gold-induced lattice expansion of palladium and hydrogen adsorption-induced phase and stress changes, a new insight into the sensing mechanism of the alloy nanowire. The mechanistic sensing details are also discussed in correlation with the growth mechanism, which provides a new insight into the synergy of the bimetallic composition of the alloy nanowires for the enhanced sensitivity for the detection of hydrogen.