Electrodeposition of Ni and Te‐doped Cobalt Triantimonide in Citrate Solutions

Abstract

Skutterudite compounds form a new class of potential candidates for thermoelectric applications. Cobalt triantimonide (CoSb3) shows good thermoelectric properties at medium and high temperatures. Doping this system with substitution elements, for either Co or Sb or both, may result in an increase of the thermoelectric figure of merit (ZT). This work focused on the electrochemical doping and characterization of films and nanowires of Co‐Sb system in citrate solutions using gold‐coated PCTE templates. The electrodeposition was performed on gold surface that was pre‐treated electrochemically to ensure reproducible results. The electrochemical treatment acted as an annealing process for the surface, which resulted in an increase in Au(111) as demonstrated by XRD. Detailed electrochemical studies including deposition‐stripping experiments was performed in order to develop a better understanding of the co‐deposition kinetics and a better control over the composition of doped Co‐Sb system. Scanning electron microscopy (SEM/EDS) helped study the morphology and the composition of the doped and undoped Co‐Sb system. Co‐deposition of Co‐Sb showed that the amount of Co is higher in nanowires than in film or mushroom caps due to the slow Sb deposition rate dictated by slow Sb(III) complex diffusion. Doped nanowires have been also obtained. Both Ni and Te electrochemical doping of the Co‐Sb system affected the composition of the deposit but there was no effect on nanowire morphology.

Template-Assisted Co-Ni Nanowire Arrays

“…On the surface of a film, it is found that the H 2 bubbles inhibit the electrochemical reaction underneath, blocking the direct contact of the electrode with the electrolyte [24]. Hydrogen evolution during the electrochemical co-deposition of two or more elements at high overpotential results in non-homogenous surface film [20,24,25]. In the NW electrode configuration, Au is found only on the pore wall closed to the surface, i.e., in a small area around the mouth of the nanopore.…”

“…This treatment also greatly increases the reproducibility of the results. The electrochemical treatment of Au in 50 mM H 2 SO 4 and the surface processes that led to a smooth Au surface are detailed elsewhere [20,21].…”

Removal of Heavy Metals from Wastewaters: A Challenge from Current Treatment Methods to Nanotechnology Applications

“…Anodized Aluminum membrane (AAO). Another template used for nanowires synthesis is the porous aluminum oxide (anodic aluminum oxide, AAO) membrane, which exhibits better stability and chemical inertia compared to PCTE [ 148 ]. AAO templates are obtained using an aluminum foil (99.99%-Merck).…”

“…Various composite nanostructures can be fabricated using electrochemical methods such as template synthesis. It is well-known that electrodeposition in AAO results in nanowire arrays of Fe [ 176 , 177 ], Co [ 166 , 173 , 178 ] and Ni [ 148 , 178 , 179 , 180 ] and their alloys. Composite materials composed of a variety of conductors, insulators, semiconductors and photoconductors were obtained.…”

Co-Ni Nanowires Arrays with Tunable Properties Obtained by Template Synthesis

“…An electrochemical treatment of the Au surface was performed in the beginning of each experiment in order to ensure same surface conditions before the electrodeposition experiment. The electrochemical treatment of Au in 50 mM H2SO4 and the surface processes that led to a smooth Au surface are detailed elsewhere [14].…”