Diamond in nanoparticle form is a promising material that can be used as a robust and chemically stable catalyst support in fuel cells. It has been studied and characterized physically and electrochemically, in its thin film and powder forms, as reported in the literature. In the present work, the electrochemical properties of undoped and boron-doped diamond nanoparticle electrodes, fabricated using the ink-paste method, were investigated. Methanol oxidation experiments were carried out in both half-cell and full fuel cell modes. Platinum and ruthenium nanoparticles were chemically deposited on undoped and boron doped diamond nanoparticles through the use of NaBH(4) as reducing agent and sodium dodecyl benzene sulfonate (SDBS) as a surfactant. Before and after the reduction process, samples were characterized by electron microscopy and spectroscopic techniques. The ink-paste method was also used to prepare the membrane electrode assembly with Pt and Pt-Ru modified undoped and boron-doped diamond nanoparticle catalytic systems, to perform the electrochemical experiments in a direct methanol fuel cell system. The results obtained demonstrate that diamond supported catalyst nanomaterials are promising for methanol fuel cells.

Many studies have used nanoscale zero valent iron (nZVI) nanoparticles to remove redox-sensitive metals (e.g., As, Cr, U, Se, Ni, Cu) from aqueous systems by absorption or reduction processes. However, very few investigations present a detailed study of the product formed after the remediation process. In order to quantify the efficiency of nZVI particles as a possible cadmium remediation agent, we prepared nZVI by sodium borohydride reduction of an iron complex, FeCl 3 $6H 2 O, at room temperature and ambient pressure. Fe 0 and nanocrystalline structures of iron oxides and oxyhydroxides were obtained with this method. We exposed the nZVI to 6 ppm of Cd 2+ and characterized the products with X-ray diffraction, X-ray absorption and X-ray photoelectron spectroscopy. Inductively coupled plasma analysis showed that the nZVI remediation efficiency of cadmium ions was between 80% and 90% in aqueous media. All of the physical characterization results confirmed the presence of Fe 0 , a-Fe 2 O 3 and FeOOH. High resolution transmission electron microscopy images showed nanofiber formation of a mixture of Fe 0 , oxyhydroxides and oxides iron formed after interacting with cadmium ions, possibly forming CdFe 2 O 4 .These results suggest that the FeOOH shell and other iron oxides in nZVI could enhance Cd 2+ removal.This removal is observed to cause a change of the initial structure of nZVI to nanofibers due to possible formation of CdFe 2 O 4 as a waste product.

A wet chemistry synthesis of Pt-Ce doped catalysts on carbon Vulcan support using an impregnation method with EDTA is presented. The composite catalyst was characterized by XRD, XPS and TEM. The catalytic activity of the prepared material was tested in a direct fuel cell using methanol, ethanol and hydrogen as fuels. The polarization and power curves showed that the Vulcan/Pt/Ce(III) doped catalysts improved the performance of the fuel cells when compared with Vulcan-Pt anode materials.

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A robust electrodeposition method consisting of the Rotating Disk Slurry Electrode (RoDSE) technique to obtain Au nanoparticles highly dispersed on a conductive carbonaceous support, i.e. Vulcan XC-72R, for ethanol electrooxidation reaction in alkaline media was developed. Ceria was used as a co-catalyst using a Ce(III)-EDTA impregnation method in order to enhance the catalytic activity and improve the catalyst's overall stability. The RoDSE method used to obtain highly dispersed Au nanoparticles does not require the use of a reducing agent or stabilizing agent and the noble-metal loading was controlled by the addition and tuning of the metal precursor concentration.Inductively coupled plasma and thermogravimetric analysis indicated that the Au loading in the catalyst was 9%.Particle size and characteristic Au fcc crystal facets were determined by X-ray diffraction. The morphology of the catalyst was also investigated using electron microscopy techniques. In addition, X-ray absorption spectroscopy was used to corroborate the presence and identify the oxidation state of Ce in the system and to observe if there are any electronic interactions within the 8% Au/CeOx/C system. Cyclic voltammetry of electrodeposited 9% Au/C and Ce promoted 8% Au/C showed a higher catalytic current density for ethanol oxidation when compared with commercially available catalysts (20% Au/C) of a higher precious metal loading. In addition, we report a higher stability towards the ethanol electrooxidation process, which was corroborated by 1 mV/s linear sweep voltammetry and chronoamperometric studies.