Electrodeposition of Pd–Ag alloy nanowires on highly oriented pyrolytic graphite

Abstract

This paper reports findings of an investigation of Pd-Ag alloy nanowires on the step edges of highly oriented pyrolytic graphite (HOPG) by electrochemical deposition at room temperature. Scanning electron microscopy (SEM) images reveal that these alloy nanowires (109-430 nm) are uniform in diameter, and have lengths up to 100-500 lm. The electrodeposition process involves the initial formation of nanowires induced at the step edges of the oxidized HOPG substrate at a very negative potential and subsequent growth at a constant low current density to coalesce the discontinuous nanowires. Alloy nanowires with a 20-25% silver content can be obtained when the ratio of Pd and Ag in the solution is carefully controlled. The SEM images demonstrate that the alloy nanowire arrays are continuous, parallel, ordered, well-aligned and have a narrow distribution of diameters. The Pd-Ag alloy nanowire arrays are promising materials for fabricating hydrogen nanosensors.

Electron Spectra Line Shape Analysis of Highly Oriented Pyrolytic Graphite and Nanocrystalline Diamond

“…CNT and HOPG, metal/alloy-based technology, seem to be promising for catalysis and/or hydrogen effective/safe gas storage. 10,13 The carbon atoms hybridize as sp 3 (typical diamond structure), sp 2 (two-dimensional graphite layered structure) or sp 1 (one-dimensional structure). The amorphous and hydrogenated amorphous carbon usually contains a mixture of C sp 3 and C sp 2 hybridizations with a negligible number of C sp 1 hybridizations.…”

Internal and External Atomic Steps in Graphite Exhibit Dramatically Different Physical and Chemical Properties

“…There are several studies associated with step edge decoration on HOPG. − In these studies, electrochemical methods were used to grow nanoscale particles and wires. − Xuan et al . reported different bonding energies between edge orientations ( e .…”

Palladium–Silver Mesowires for the Extended Detection of H2

“…Mainly two different plating solutions were used for the electrochemical-deposition of PdAg alloys. Yu et al have used nitrate Pd 2+ and Ag + salts in sodium nitrate electrolyte for the single pulse deposition of PdAg nanowires . The solubilization of Pd(NO 3 ) 2 is, however, difficult to achieve in nitrate aqueous solutions, and the resulting solutions are rather unstable.…”

“…Yu et al have used nitrate Pd 2+ and Ag + salts in sodium nitrate electrolyte for the single pulse deposition of PdAg nanowires. 31 The solubilization of Pd(NO 3 ) 2 is, however, difficult to achieve in nitrate aqueous solutions, and the resulting solutions are rather unstable. In contrast to this chloride-free approach, Monty et al have electrochemically prepared PdAg nanowires from stable Ag + / Pd 2+ mixtures in 2 M NaCl-based electrolytes.…”