Electrooxidation of Methanol on upd-Ru and upd-Sn Modified Pt Electrodes

Electrooxidation of 2-propanol on the mixture of nanoparticles of Pt and RuO2 supported on Ti

A thermal process was employed to prepare a catalyst consisting of a mixture of metallic-Pt and rutile RuO2 nanocrystals. This catalyst was used for the electrooxidation of 2-propanol in an alkaline solution. The effect of the catalyst composition on its microstructure, surface properties and catalytic activity was examined. With increasing the RuO2 content, the catalytic activity increases, reaches its maximum and then decreases. The catalytic effect is a result of the bifunctional mechanism of the mixture of Pt and RuO2 nanocrystals. The RuOHad particles are formed on Ru atoms of the RuO2 nanocrystals at potentials more negative than on Pt atoms. These oxy-species facilitate the dehydrogenation, breaking of C–C bonds and oxidation of both 2-propanol and its intermediates, adsorbed on assemblies of adjacent Pt atoms.

Methanol decomposition reactions over a boron-doped graphene supported Ru–Pt catalyst

In-depth investigations of adsorption and decomposition of methanol over boron-doped graphene supported Ru–Pt catalyst are presented using periodic density functional theory calculations. Methanol decomposition on such catalyst proceeds through formation of methoxide (CH₃O) and via stepwise dehydrogenation of formaldehyde (CH₂O), formyl (CHO), and carbon monoxide (CO).

Efficient CO Oxidation Using Dendrimer-Encapsulated Pt Nanoparticles Activated with <2% Cu Surface Atoms

In this paper, we show that the onset potential for CO oxidation electrocatalyzed by ∼2 nm dendrimer-encapsulated Pt nanoparticles (Pt DENs) is shifted negative by ∼300 mV in the presence of a small percentage (<2%) of Cu surface atoms. Theory and experiments suggest that the catalytic enhancement arises from a cocatalytic Langmuir-Hinshelwood mechanism in which the small number of Cu atoms selectively adsorb OH, thereby facilitating reaction with CO adsorbed to the dominant Pt surface. Theory suggests that these Cu atoms are present primarily on the (100) facets of the Pt DENs.

Biobutanol as Fuel for Direct Alcohol Fuel Cells-Investigation of Sn-Modified Pt Catalyst for Butanol Electro-oxidation

Direct alcohol fuel cells (DAFCs) mostly use low molecular weight alcohols such as methanol and ethanol as fuels. However, short-chain alcohol molecules have a relative high membrane crossover rate in DAFCs and a low energy density. Long chain alcohols such as butanol have a higher energy density, as well as a lower membrane crossover rate compared to methanol and ethanol. Although a significant number of studies have been dedicated to low molecular weight alcohols in DAFCs, very few studies are available for longer chain alcohols such as butanol. A significant development in the production of biobutanol and its proposed application as an alternative fuel to gasoline in the past decade makes butanol an interesting candidate fuel for fuel cells. Different butanol isomers were compared in this study on various Pt and PtSn bimetallic catalysts for their electro-oxidation activities in acidic media. Clear distinctive behaviors were observed for each of the different butanol isomers using cyclic voltammetry (CV), indicating a difference in activity and the mechanism of oxidation. The voltammograms of both n-butanol and iso-butanol showed similar characteristic features, indicating a similar reaction mechanism, whereas 2-butanol showed completely different features; for example, it did not show any indication of poisoning. Ter-butanol was found to be inactive for oxidation on Pt. In situ FTIR and CV analysis showed that OHads was essential for the oxidation of primary butanol isomers which only forms at high potentials on Pt. In order to enhance the water oxidation and produce OHads at lower potentials, Pt was modified by the oxophilic metal Sn and the bimetallic PtSn was studied for the oxidation of butanol isomers. A significant enhancement in the oxidation of the 1° butanol isomers was observed on addition of Sn to the Pt, resulting in an oxidation peak at a potential ∼520 mV lower than that found on pure Pt. The higher activity of PtSn was attributed to the bifunctional mechanism on PtSn catalyst. The positive influence of Sn was also confirmed in the PtSn nanoparticle catalyst prepared by the modification of commercial Pt/C nanoparticle and a higher activity was observed for PtSn (3:1) composition. The temperature-dependent data showed that the activation energy for butanol oxidation reaction over PtSn/C is lower than that over Pt/C.

Development of a PtSn bimetallic catalyst for direct fuel cells using bio-butanol fuel

PtSn showed a higher activity and lower activation energy towards butanol electrooxidation compared to pure Pt.

Facile synthesis of catalytically active platinum nanosponges, nanonetworks, and nanodendrites

Facile synthesis: Pt nanosponges, nanonetworks, and nanodendrites (see figure) are synthesized through a unique galvanic replacement reaction between Te nanowires and PtCl(6) (2-) ions in the presence of sodium dodecyl sulfate. The three Pt nanomaterials all have large active surface areas and highly electrocatalytic activities for the oxidation of methanol.In this paper, we report a simple approach for the preparation of various porous Pt nanomaterials (NMs) in aqueous solution. Employing different temperatures and concentrations of sodium dodecyl sulfate (SDS), we obtained Pt nanosponges, Pt nanonetworks, and Pt nanodendrites from the reduction of PtCl(6) (2-) ions via galvanic replacement reactions with Te nanowires (length: 879 nm; diameter: 19 nm). At ambient temperature, Pt nanosponges and Pt nanodendrites formed selectively in the presence of SDS at concentrations of <10 mM and>50 mM, respectively. At elevated reaction temperatures, we obtained Pt nanonetworks and Pt nanodendrites in the presence of SDS at concentrations of <10 mM and >50 mM, respectively. Transmission electron microscopy images revealed that these Pt NMs were all composed of one dimensional Pt nanostructures having widths of 3.0+/-1.0 nm and lengths of 17.0+/-4.8 nm. Cyclic voltammetry data indicated that the as-prepared Pt nanonetworks, nanosponges, and nanodendrites possessed large electrochemically active surface areas (77.0, 70.4, and 41.4 m(2) g(-1), respectively). For the electrocatalytic oxidation of methanol, the ratio of the forward oxidation peak current (I(f)) to the backward peak current (I(b)) of the Pt nanodendrites, nanosponges, and nanonetworks were all high (I(f)/I(b)=2.88, 2.66, and 2.16, respectively). These three NMs exhibit greater electrocatalytic activities and excellent tolerance toward poisoning species for the oxidation of methanol when compared with the performance of standard Pt NMs.

Platinum-coated gold nanoporous film surface: electrodeposition and enhanced electrocatalytic activity for methanol oxidation

This report describes the preparation of Pt-nanoparticle-coated gold-nanoporous film (PGNF) on a gold substrate via a simple "green" approach. The gold electrode that has been anodized under a high potential of 5 V is reduced by freshly prepared ascorbic acid (AA) solution to obtain gold nanoporous film electrode. Then the Pt nanoparticle is grown on the electrode by cyclic voltammetry (CV). The resulting PGNF electrode has highly ordered arrangement and large surface area, as verified by scanning electron microscopy (SEM) and CV, suggesting that the nanoporous gold film electrode provides a good matrix for obtaining PGNF with high surface area. Furthermore, the as-prepared PGNF electrode exhibited high electrocatalytic activity toward methanol oxidation in a 0.5 M H 2SO 4 solution containing 1.5 M methanol. The present novel strategy is expected to reduce the cost of the Pt catalyst remarkably.