Synergitic Promotion of Electrooxidation of Methanol of Carbon-Supported PT-SN Catalysts

Electrooxidation of methanol in sulphuric acid on carbon-supported electrodes containing Pt-Sn bimetal catalysts prepared by an in-situ route is reported, The catalysts have been characterized employing chemical analyses, XRD, and XANES data in conjunction with electrochemistry. This study suggests that the Sn content in Pt-Sn bimetals produces: (i) a charge transfer from Sn to Pt and (ii) an increase in the coverage of adsorbed methanolic residues with the Sn content. From the electrode-kinetics data, it is inferred that while the electrodes of (3:3) Pt-Sn/C catalyst involve a 2-electron rate-limiting step akin to Pt/C electrodes, it is shifted to only 1-electron on (3:2) Pt-Sn/C, (3:3) Pt-Sn/C, and (3:4) Pt-Sn/C electrodes.

Electrooxidation of methanol in sulfuric-acid electrolyte on platized-carbon electrodes with several functional-group characteristics

The effect of acid/base functional-groups associated with platinized-carbon electrodes on their catalytic activity toward electro-oxidation of methanol in sulfuric acid electrolyte at 60-degrees-C is studied. Platinized-carbon electrodes with sm amounts of functional groups exhibit higher catalytic activity compared to those with large concentrations of acidic/basic surface functionalities. The overpotential for methanol oxidation is minimum on electrodes of platinized carbons with pHzpc values between 6 and 7. An x-ray photoelectron spectroscopic study of various platinized carbons suggests that the acid/base surface functional-groups produce ample amounts of surface Pt-oxides and a consequent decrease in activity toward methanol oxidation.

Methanol electrooxidation on carbon-supported Pt-WO3−x electrodes in sulphuric acid electrolyte

Electrooxidation of methanol has been studied in sulphuric acid electrolyte at 60 degrees C on carbon-supported Pt-WO3-x, electrodes employing varying amounts of WO3-x,. It is found that the electrodes containing (3:1) Pt-WO3-x, composite catalyst exhibit a higher catalytic activity towards methanol electrooxidation than platinized carbon electrodes without WO3-x. In the light of the XPS and XRD data on the carbon-supported (3:1) Pt-WOx sample, it is speculated that the WOx is present in the form of an oxyhydroxide, which can promote surface oxy-species on platinum by proton transfer.

Electrooxidation of formic acid at platinum nanoclusters electrodeposited on PEDOT coated carbon paper electrode

Nanoclusters of Pt were electrochemically deposited on a conducting polymer, namely, poly(3,4-ethylenedioxythiophene) (PEDOT), which was also electrochemically deposited on carbon paper current collector. PEDOT facilitated uniform distribution of Pt nanoclusters, when compared with Pt electrodeposition on bare carbon paper substrate. Spectroscopy data indicated absence of any interaction between PEDOT and Pt. The electrochemically active surface area as measured from carbon monoxide adsorption followed by its oxidation was several times greater for Pt-PEDOT/C electrode in comparison with Pt/C electrode. The catalytic activity of Pt-PEDOT/C electrode for electrooxidation of formic acid was significantly greater than that of Pt/C electrode. Amperometry data suggested that the electrodes were stable for continuous oxidation of HCOOH.

Pt-Ru decorated self-assembled TiO2-carbon hybrid nanostructure for enhanced methanol electrooxidation

Porous titanium oxide-carbon hybrid nanostructure (TiO2-C) with a specific surface area of 350 m(2)/g and an average pore-radius of 21 center dot 8 is synthesized via supramolecular self-assembly with an in situ crystallization process. Subsequently, TiO2-C supported Pt-Ru electro-catalyst (Pt-Ru/TiO2-C) is obtained and investigated as an anode catalyst for direct methanol fuel cells (DMFCs). X-ray diffraction, Raman spectroscopy and transmission electron microscopy (TEM) have been employed to evaluate the crystalline nature and the structural properties of TiO2-C. TEM images reveal uniform distribution of Pt-Ru nanoparticles (d (Pt -aEuro parts per thousand Ru) = 1 center dot 5-3 center dot 5 nm) on TiO2-C. Methanol oxidation and accelerated durability studies on Pt-Ru/TiO2-C exhibit enhanced catalytic activity and durability compared to carbon-supported Pt-Ru. DMFC employing Pt-Ru/TiO2-C as an anode catalyst delivers a peak-power density of 91 mW/cm(2) at 65 A degrees C as compared to the peak-power density of 60 mW/cm(2) obtained for the DMFC with carbon-supported Pt-Ru anode catalyst operating under similar conditions.

High catalytic activity of Au-PEDOT nanoflowers toward electrooxidation of glucose

Electrochemically deposited porous film of poly(3,4-ethylenedioxythiophene) (PEDOT) on carbon paper current collector is used as the substrate for electrochemical deposition of Au. PEDOT facilitates the formation of Au nanoflowers with an enhanced electrochemical active surface area, when compared with sub-micron size Au particles deposited on bare carbon paper electrode. Owing to enhanced surface area of Au nanoflowers, the Au-PEDOT/C electrode shows greater activity than Au/C electrode toward electrooxidation of glucose in 0.5 M NaOH electrolyte. Cyclic voltammetry studies show that the peak current density increases with increase in concentrations of glucose and NaOH in the electrolyte. H-1-NMR spectroscopy data indicates that sodium formate and gluconate are the primary products of electrooxidation of glucose on Au-PEDOT/C electrode. Repetitive cyclic voltametry and amperometry studies suggest that the electrochemical stability of Au-PEDOT/C electrode is higher than that of Au/C electrode. Thus, electrochemically deposited nanostructured Au on PEDOT/C is an efficient catalyst for direct glucose oxidation in alkaline media. (C) 2013 The Electrochemical Society. All rights reserved.

Reduced graphene oxide-supported nickel oxide catalyst with improved CO tolerance for formic acid electrooxidation

The superior catalytic activity along with improved CO tolerance for formic acid electro-oxidation has been demonstrated on a NiO-decorated reduced graphene oxide (rGO) catalyst. The cyclic voltammetry response of rGO-NiO/Pt catalyst elucidates improved CO tolerance and follows direct oxidation pathway. It is probably due to the beneficial effect of residual oxygen groups on rGO support which is supported by FT-IR spectrum. A strong interaction of rGO support with NiO nanoparticles facilitates the removal of CO from the catalyst surface. The chronoamperometric response indicates a higher catalytic activity and stability of rGO-NiO/Pt catalyst than the NiO/Pt and unmodified Pt electrode catalyst for a prolonged time of continuous oxidation of formic acid. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Nanoflowers of PdRu on PEDOT for Electrooxidation of Glycerol and Its Analysis

Poly(3,4-ethylenedioxythiophene) (PEDOT) supported PdRu catalysts with various Pd:Ru atomic ratios are prepared by one step electrodeposition method. The catalysts are characterised by several physico-chemical techniques. The morphology depends on Pd:Ru ratio. The nanoflowers of Pd5Ru catalyst are deposited on PEDOT surface in an alloy form. Cyclic voltammetry experiments indicate that Ru improves the catalytic activity of Pd for glycerol oxidation significantly. However, the oxidation of glycerol is not observed on Ru-PEDOT/C electrode. Amongst all compositions, Pd5Ru nanoflowers on PEDOT exhibit the highest electrocatalytic activity and stability. Cyclic voltammetry and differential pulse voltammetry experiments are performed for the analysis of glycerol. Pd5Ru-PEDOT/C electrode is highly sensitive towards glycerol detection with sensitivity of 99.8 mu A cm(-2) mu M-1 and low detection limit of 0.1 mu M. Thus, electrochemically deposited nanoflowers Pd5Ru on PEDOT are efficient catalysts for direct glycerol oxidation as well as for analysis in alkaline media. (C) 2015 Elsevier Ltd. All rights reserved.

Methanol oxidation on carbon-supported platinum-tin electrodes in sulfuric acid

A study is made of the electrooxidation of methanol in sulfuric acid on carbon-supported electrodes containing platinum-tin bimetal catalysts that are prepared by an in situ potentiometric-characterization route. The catalysts are investigated by employing chemical analyses, X-ray diffraction (XRD), X-ray absorption-near-edge spectroscopy (XANES) and X-ray photoelectron spectroscopy (XPS) data in conjunction with electrochemical measurements. From the electrochemical data, it is inferred that while an electrode with (3:1) Pt-Sn/C catalyst involves a two-electron rate-limiting step akin to platinum-on-carbon electrodes, it is shifted to a one-electron mechanism on electrodes with (3:2)Pt-Sn/C, (3:3)Pt-Sn/C, and (3:4)Pt-Sn/C catalysts. The study suggests that the tin content in the platinum-tin bimetal catalyst produces: (i) a charge transfer from tin to platinum; (ii) an increase in the coverage of adsorbed methanolic residues with increase in the tin content, as indicated by the shift in rest potential of the electrodes towards the reversible value for oxidation of methanol (0.043 V versus SHE), and (iii) a decrease in the overall content of higher valent platinum sites in the catalyst.

Methanol oxidation on carbon-supported platinum-tin electrodes in sulfuric acid

A study is made of the electrooxidation of methanol in sulfuric acid on carbon-supported electrodes containing platinum-tin bimetal catalysts that are prepared by an in situ potentiometric-characterization route. The catalysts are investigated by employing chemical analyses, X-ray diffraction (XRD), X-ray absorption-near-edge spectroscopy (XANES) and X-ray photoelectron spectroscopy (XPS) data in conjunction with electrochemical measurements. From the electrochemical data, it is inferred that while an electrode with (3:1) Pt-Sn/C catalyst involves a two-electron rate-limiting step akin to platinum-on-carbon electrodes, it is shifted to a one-electron mechanism on electrodes with (3:2)Pt-Sn/C, (3:3)Pt-Sn/C, and (3:4)Pt-Sn/C catalysts. The study suggests that the tin content in the platinum-tin bimetal catalyst produces: (i) a charge transfer from tin to platinum; (ii) an increase in the coverage of adsorbed methanolic residues with increase in the tin content, as indicated by the shift in rest potential of the electrodes towards the reversible value for oxidation of methanol (0.043 V versus SHE), and (iii) a decrease in the overall content of higher valent platinum sites in the catalyst.

Electrocatalytic oxidation of 1,2-propanediol on electrodeposited Pd-poly(3,4-ethylenedioxythiophene) nanodendrite films in alkaline medium

Electrochemical deposition of Pd on conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) coated carbon paper electrode results in the formation of a stable dendritic film of Pd. In the absence of the PEDOT under-layer, Pd deposition is smooth and non-dendritic. Both Pd-PEDOT/C and Pd/C electrodes are studied for electrooxidation of 1,2-propanediol (PD) in an alkaline electrolyte. Owing to enhanced surface area and surface defects on dendritic Pd, the Pd-PEDOT/C electrode exhibits greater catalytic activity than the Pd/C electrode. Cyclic voltammetry studies suggest that peak current density increases with an increase in concentrations of PD and NaOH in the electrolyte. Repetitive cyclic voltammetry and amperometry studies indicate that Pd-PEDOT/C electrode possesses a high electrochemical stability with greater catalytic activity than Pd/C electrode toward electrooxidation of PD. (C) 2012 Elsevier Ltd. All rights reserved.

Electrocatalytic oxidation of C-3-aliphatic alcohols on electrodeposited Pd-PEDOT nanodendrites in Alkaline medium

Nanodendritic Pd is electrodeposited on poly(3,4-ethylenedioxythiophene) (PEDOT) coated carbon paper electrode. Electrodeposited Pd is non-dendritic in the absence of PEDOT. The electrooxidation of C-3-aliphatic alcohols, namely, propanol (PA), 1,2- propanediol (1, 2-PD), 1, 3-propanediol (1, 3-PD), and glycerol (GL) is studied in 1.0 M NaOH. The catalytic activity of nanodendritic Pd is greater than that of non-dendritic Pd for oxidation of the four alcohols molecules. Among those molecules the oxidation rate increases as: PA< 1, 2-PD < 1, 3-PD < GL. The cyclic voltammetric oxidation current peak appearing in the reverse direction of the sweep is greatly influenced by the nature of alcohol. The reduction of oxide film on Pd surface is attributed to affect the magnitude of backward peak current density. The amperometry and repeated cyclic voltammetry data suggest a high stability of nanodendritic Pd in alkaline medium. Glycerol is expected to be an appropriate alcohol for application as a fuel in alkaline fuel cells at nanodendritic electrodeposited Pd.