Search

Highlights: [•] Graphites and carbon blacks have been tested in the CWPO of phenol (C Phenol,0 =1g/L, 80°C). [•] Non-porous carbon blacks without mineral impurities are efficient and stable catalysts. [•] Low adsorption capacity prevents carbon deactivation by adsorbed oligomer by-products. [•] Total phenol conversion with 100% efficiency of H2O2 consumption was achieved in 20h. [ABSTRACT FROM AUTHOR]

Highlights: [•] Commercial ACs with different physico-chemical characteristics have been tested. [•] The significant coverage of the AC surface by phenol is the approach studied. [•] We report hydrogen peroxide efficiencies of around 100% in the CWPO of phenol. [•] The removal of phenol takes place on the carbon surface and in liquid phase. [•] The AC activity can be easily recovered by oxidative regeneration at 350°C. [ABSTRACT FROM AUTHOR]

Abstract: The effect of Co addition to carbon nanotubes supported Pt in the methanol oxidation reaction has been investigated by means of differential electrochemical mass spectrometry (DEMS). It has been observed that the CO2 efficiency increases in carbon nanotubes supported PtCo compared to its homologous Pt catalysts, especially at potentials lower than 0.55V. Despite of this, the Faradaic current reached by the bimetallic catalysts in the methanol electrooxidation was lower than those recorded on the monometallic samples. This is because Co addition difficult finding enough Pt vicinal sites for methanol dehydrogenation. On the other hand, it has been found that alloying Pt with Co, shifts down the d-band center of the larger element, so the strength of the interaction with adsorbates decreases. Consequently, it will be easier to oxidize COad on the bimetallic surface. Furthermore, the necessary –OHad species for the COad oxidation to CO2 will be provided by the CNTs themselves. [ABSTRACT FROM AUTHOR]

Abstract: A series of carbon supported PtAu electrocatalysts has been prepared. The performance of the samples in the methanol oxidation reaction and in the oxygen reduction reaction has been investigated by means of electrochemical techniques. The combined process, oxygen reduction reaction in the presence of methanol, has also been studied by electrochemical methods and in a single-cell. Irrespective of the performance of the samples in the oxygen reduction reaction, the ones displaying poor activity in the methanol oxidation reaction are the optimum cathode electrocatalysts for direct methanol fuel cell applications. The role of Au was found to be dependent on the actual nature of the catalyst. When alloyed, the role of Au on the methanol oxidation reaction is negligible. This is the first time that Au is being proposed as a component of methanol resistant cathode electrocatalysts. [Copyright &y& Elsevier]

The activity of carbon supported palladium-based catalysts towards ethanol oxidation reaction in alkaline medium is investigated. To this end, Pd and Pd x Ru (x = 1, 6, 12) materials are synthesized supported on Vulcan XC72R by a modified impregnation method. These materials are characterized physicochemically and their composition varies between 40 and 50 wt. % of metal content. The mean size of nanoparticles is below 4 nm, and the size of the majority of particles ranges from 2 to 6 nm. The catalytic activity of these samples is also tested in half-cell and alkaline membrane direct ethanol fuel cell (AMDEFC). Lower onset potential and higher oxidation current densities is observed in palladium-rich bimetallic catalysts. By using the prepared samples as anode of AMDEFC and a commercial membrane of polybenzimidazole as solid electrolyte, the maximum power density is observed for Pd 12 Ru/C, 97 mW cm −2 , almost doubling the value achieved by the catalyst Pd/C (50 mW cm −2 ), and above the obtained by commercial PtRu/C catalyst (89 mW cm −2 ). [ABSTRACT FROM AUTHOR]

Abstract: Functionalized carbonaceous materials have been investigated as supports of PtRu nanoparticles for the electrooxidation of methanol, using such conventional electrochemical methods as cyclic voltammetry and chronoamperommetry and by measurements in a CH3OH/O2-fed single cell. Further, to understand the effect of oxygen-containing groups on the supports in the methanol oxidation reaction (MOR), a kinetic study of the catalyst that has the best behavior in this process has been performed. The study at different temperatures of PtRu nanoparticles supported in multiwall carbon nanotubes (MWCNTs) with a high amounts of functional groups—PtRuCNT-ST—show that there was low CO poisoning during the MOR on this catalyst. The low apparent energy on PtRuCNT-ST in the MOR was attributed to CO diffusion or to the dissociative adsorption of methanol. Both factors had a beneficial effect on the oxygen-containing groups on MWCNTs, facilitating oxidation of the carbonaceous intermediates to CO2 or HCOOH. These findings have been confirmed by studies in a single cell feeding with CH3OH/O2, demonstrating that PtRuCNT-ST is the best-performing anodic electrode. [Copyright &y& Elsevier]