Keqiang Ding

Ultrafine FePd Nanoalloys Decorated Multiwalled Cabon Nanotubes toward Enhanced Ethanol Oxidation Reaction.

Ultrafine iron-palladium (FePd) nanoalloys deposited on γ-Fe2O3, FePd-Fe2O3, further anchored on carboxyl multiwalled carbon nanotubes (MWNTs-COOH), FePd-Fe2O3/MWNTs, were successfully synthesized by a facile one-pot solution based method as thermally decomposing palladium acetylacetonate (Pd(acac)2) and iron pentacarbonyl (Fe(CO)5) in a refluxing dimethylformamide solution in the presence of MWNTs-COOH. A 3.65 fold increase of peak current density was observed in cyclic voltammetry (CV) for ethanol oxidation reaction (EOR) compared with that of Pd/MWNTs after normalizing to Pd mass. The greatly enhanced tolerance stability toward poisoning species and largely reduced charge transfer resistance were also obtained in chronoamperometry and electrochemical impedance spectroscopy due to the downward shifted d-band center of FePd alloy, easily formed oxygen containing species on Fe2O3, and the stabilizing role of the MWNTs.

Optimal Electrocatalytic Pd/MWNTs Nanocatalysts toward Formic Acid Oxidation

The operating conditions such as composition of electrolyte and temperature can greatly influence the formic acid (HCOOH) oxidation reaction (FAOR). Palladium decorated multi-walled carbon nanotubes (Pd/MWNTs) were successfully synthesized and employed as nanocatalysts to explore the effects of formic acid, sulfuric acid (H2SO4) concentration and temperature on FAOR. Both the hydrogen adsorption in low potential range and the oxidation of poisoning species during the high potential range in cyclic voltammetry were demonstrated to contribute to the enhanced electroactivity of Pd/MWNTs. The as-synthesized Pd/MWNTs gave the best performance under a condition with balanced adsorptions of HCOOH and H2SO4 molecules. The dominant dehydrogenation pathway on Pd/MWNTs can be largely depressed by the increased dehydration pathway, leading to an increased charge transfer resistance (Rct ). Increasing HCOOH concentration could directly increase the dehydration process proportion and cause the production of COads species. H2SO4 as donor of H+ greatly facilitated the onset oxidation of HCOOH in the beginning process but it largely depressed the HCOOH oxidation with excess amount of H+. Enhanced ion mobility with increasing the temperature was mainly responsible for the increased current densities, improved tolerance stabilities and reduced Rct values, while dehydration process was also increased simultaneously.

Hydrothermal process synthesized electrocatalytic multi-walled carbon nanotubes-inserted gold composite microparticles toward ethanol oxidation reaction

Composite microparticles consisting of large gold (Au) particles embedded with multi-walled carbon nanotubes (MWCNTs), denoted as MWCNTs-Au, have been successfully prepared by a facile hydrothermal process of gold(III) chloride (AuCl3) in a MWCNT aqueous solution. X-ray diffraction and scanning electron microscopy reveal that the obtained Au particles have an average diameter of about 500xa0nm and some MWCNTs are inserted into the Au particles. The MWCNTs-Au composites in the ethanol oxidation reaction (EOR) show quite different shape of cyclic voltammograms (CVs) toward EOR when compared to the previous CV reports on the pure Au substrate.