Vladimir Linkov

Biomass-derived activated carbon as high-performance non-precious electrocatalyst for oxygen reduction

A new type of Fe and N doped carbon material is synthesized by pyrolyzing ferric chloride doped egg white (EW) and the proposed synthetic route is easy, green, and low-cost. In addition, the as-prepared sample exhibits a feasible magnetism and comparable oxygen reduction reaction (ORR) activity to commercial Pt/C.

Highly dispersed ultrafine Pt nanoparticles on hydrophilic N-doped carbon tubes for improved methanol oxidation

Using hydrophilic nitrogen-doped carbon tubes (N-CTs) as supports, prepared by carbonization of the mixture of lysine and ferric chloride, ultrafine Pt nanoparticles were highly dispersed on the N-CT sidewalls. Electrochemical analyses found that the methanol oxidation activity of the Pt/N-CTs was ∼2.1 times that of a commercial Pt/C catalyst. The improved performance correlated to the high dispersion of ultrafine Pt nanoparticles and the synergistic effect between Pt and the N-CTs.

Sulfonated polyether ether ketone (PEEK-WC)/ phosphotungstic acid composite : Preparation and characterization of the fuel cell membranes

Sulfonated poly(oxa-p-phenylene-3,3-phthalido-p-phenylene-oxa-p-phenylene-oxy-phenylene) (PEEK-WC) membranes with various degrees of sulfonation (DS) were prepared, and their electrochemical and thermal properties were studied. Composites were formed by adding the hydrated phosphotungstic acid (PWA). The membrane (DS = 0.96, PWA = 50 %) conductivity was increased to 3.5 x 10-2 S cm-1 at room temperature and 6.0 x 10-2 S cm-1 at 80 °C. The composite membrane with a low amount of PWA embedded, showed lower methanol crossover in comparison to Nafion®. The addition of PWA increased the water retention of the composite membrane.

The Effect of PtRuIr Nanoparticle Crystallinity in Electrocatalytic Methanol Oxidation

Two structural forms of a ternary alloy PtRuIr/C catalyst, one amorphous and one highly crystalline, were synthesized and compared to determine the effect of their respective structures on their activity and stability as anodic catalysts in methanol oxidation. Characterization techniques included TEM, XRD, and EDX. Electrochemical analysis using a glassy carbon disk electrode for cyclic voltammogram and chronoamperometry were tested in a solution of 0.5 mol L−1 CH3OH and 0.5 mol L−1 H2SO4. Amorphous PtRuIr/C catalyst was found to have a larger electrochemical surface area, while the crystalline PtRuIr/C catalyst had both a higher activity in methanol oxidation and increased CO poisoning rate. Crystallinity of the active alloy nanoparticles has a big impact on both methanol oxidation activity and in the CO poisoning rate.

Electrochemical Evaluation of Pt-Based Binary Catalysts on Various Supports for the Direct Methanol Fuel Cell

Multi-walled carbon nanotubes (MWCNTs), TiO2, MoO2, and carbon black Vulcan XC-72 were investigated as supports for PtRu and PtSn catalysts. X-ray diffraction (XRD) confirmed that all electrocatalysts examined display characteristic patterns similar to that of the Pt/C electrocatalyst, an indication that the catalysts have predominantly the Pt face-centered cubic (fcc) crystal structure. High-resolution transmission electron microscopy (HRTEM) images showed spherical PtRu and PtSn nanoparticles with a narrow particle size distribution, dispersed on the support materials. The metal loading for the prepared electrocatalyst was estimated using energy-dispersive X-ray spectroscopy (EDS), and it was observed to be closest to that of the catalysts supported on Vulcan XC-72. Cyclic voltammograms showed PtSn/C to be the most active, as it possessed a higher electroactive surface area than that of the other catalysts, followed by Pt/C > PtRu/MWCNT > PtRu/C > PtSn/MWCNT > PtSn/MoO2 > PtRu/MoO2 > PtSn/TiO2 > PtRu/TiO2. It was also observed that catalysts supported on MWCNTs were more active than those supported on metal oxides. Furthermore, catalysts supported on MWCNTs proved to be more stable than all the other supported catalysts examined. Therefore, MWCNTs have been proven in this study to be the best material for supporting electrocatalysts for direct methanol fuel cells.

Effect of ni core structure on the electrocatalytic activity of pt-ni/c in methanol oxidation.

Methanol oxidation catalysts comprising an outer Pt-shell with an inner Ni-core supported on carbon, (Pt-Ni/C), were prepared with either crystalline or amorphous Ni core structures. Structural comparisons of the two forms of catalyst were made using transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), and methanol oxidation activity compared using CV and chronoamperometry (CA). While both the amorphous Ni core and crystalline Ni core structures were covered by similar Pt shell thickness and structure, the Pt-Ni(amorphous)/C catalyst had higher methanol oxidation activity. The amorphous Ni core thus offers improved Pt usage efficiency in direct methanol fuel cells.

Synthesis of carbon-supported PdSn–SnO2 nanoparticles with different degrees of interfacial contact and enhanced catalytic activities for formic acid oxidation

The conjunction of the PdSn alloy and SnO2 is of interest for improving catalytic activity in formic acid oxidation (FAO). Here, we report the synthesis of PdSn-SnO2 nanoparticles and a study of their catalytic FAO activity. Different degrees of interfacial contact between SnO2 and PdSn were obtained using two different stabilizers (sodium citrate and EDTA) during the reduction process in catalyst preparation. Compared to the PdSn alloy, PdSn-SnO2 supported on carbon black showed enhanced FAO catalytic activity due to the presence of SnO2 species. It was also found that interfacial contact between the PdSn alloy and the SnO2 phase has an impact on the activity towards CO oxidation and FAO.

Overview of Membrane Electrode Assembly Preparation Methods for Solid Polymer Electrolyte Electrolyzer

© 2012 Bladergroen et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Overview of Membrane Electrode Assembly Preparation Methods for Solid Polymer Electrolyte Electrolyzer

Synthesis and optimisation of IrO2 electrocatalysts by Adams fusion method for solid polymer electrolyte electrolysers

IrO 2 as an anodic electrocatalyst for the oxygen evolution reaction (OER) in solid polymer electrolyte (SPE) electrolysers was synthesised by adapting the Adams fusion method. Optimisation of the IrO 2 electrocatalyst was achieved by varying the synthesis duration (0.5 - 4 hours) and temperature (250 - 500°C). The physical properties of the electrocatalysts were characterised by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray diffraction (XRD). Electrochemical characterisation of the electrocatalysts toward the OER was evaluated by chronoamperometry (CA). CA analysis revealed the best electrocatalytic activity towards the OER for IrO 2 synthesised for 2 hours at 350 o C which displayed a better electrocatalytic activity than the commercial IrO 2 electrocatalyst used in this study. XRD and TEM analyses revealed an increase in crystallinity and average particle size with increasing synthesis duration and temperature which accounted for the decreasing electrocatalytic activity. At 250°C the formation of an active IrO 2 electrocatalyst was not favoured.

Electroconductive coatings on porous ceramic supports

The preparation of porous conductive coatings on porous ceramic supports for potential use in electrosynthesis, anodic decomposition of organic compounds and electrosorption units is described. The prepared conductive coatings on porous ceramic supports consisted either of carbon, gold or nickel, or a combination of carbon and gold. Carbon coatings were obtained by pyrolytic decomposition of liquid petroleum gas (LPG), gold was sputter coated and nickel coatings were formed by electroless plating. The permeability for water and electrical resistance of each coated support were measured and compared. Pyrolytic carbon was deposited throughout the support whereas the nickel and gold coatings were formed on the outer surface of the support. The resistance of a carbon coating could be regulated between 0.5 and 2 Ω cm−1 of support while the permeability of the carbonized support was as high as 75% of the permeability of the unmodified support. The nickel and gold coatings had no significant effect on the permeability and could be prepared with a resistance of 0.25 and 1 Ω cm−1 of support, respectively.