Activity For Ethylene Glycol Oxidation Research Articles

Robust poly(3,4-ethylenedioxythiophene) granules loaded Cu/Ni-doped Pd catalysts for high-efficiency electrooxidation of ethylene glycol

In our work, poly(3,4-ethylenedioxythiophene) (PEDOT) granules supported Cu/Ni-doped Pd electrocatalysts (PdCu/PEDOT and PdNi/PEDOT) were synthesized for ethylene glycol (EG) oxidation in alkaline medium. The amorphous PEDOT granules as the catalyst supports provide plenty of attachment sites for PdCu and PdNi nanoparticles. The optimized Pd1Cu3/PEDOT and Pd7Ni3/PEDOT catalysts both perform superior mass-based activity, area-based activity and intrinsic activity for EG oxidation as compared to other control samples. Moreover, chronoamperometry and long-term cyclic voltammetry tests demonstrate that the Pd1Cu3/PEDOT catalyst performs optimal anti-poisoning capability and catalytic durability. The outstanding electrocatalytic performance can be attributed to the favourable dispersion of Pd1Cu3 and Pd7Ni3 nanoparticles on the PEDOT granules and the synergistic effects between Pd, Cu/Ni atoms and the electron-rich conjugated structure of PEDOT. In summary, this work synthesized two Pd/PEDOT-based electrocatalysts with promising catalytic application prospect in direct ethylene glycol fuel cell (DEGFC), which may provide some theoretical support for the design and synthesis of competent electrocatalysts for DEGFC.

Ethylene glycol oxidation on ternary PtRhNi/C electrocatalyst with different metal compositions

ABSTRACT Direct Alcohol Fuel Cells (DAFC’s) are an alternative to fuel cell systems and when is used alkaline medium this has an increase performance. The alkaline direct alcohol fuel cells (ADAFC's) have some advantages such as low-emission, high energy efficiency, improved oxidation kinetics, low crossover and in addition there is a broad range of materials that can be used as catalysts. The ethylene glycol (EG) has received attention in recent decades as an alternative fuel for ADAFC, but like others alcohols must be completed oxidized to generate full power energy. In this study we analyzed ternary PtRhNi/C electrocatalysts with different compositions, synthesized by alcohol reduction method, and compared to Pt/C ETEK. The active area, catalytic activity and stability of catalysts for ethylene glycol oxidation in alkaline medium were studied by cyclic voltammetry, CO stripping voltammetry and chronoamperometry tests. XRD technique was applied to physical characterization and it was observed the formation of alloy. The average crystallite size was calculated from the Scherrer equation. The Pt92Rh7Ni1/C electrocatalyst shows a larger electrochemically active area and consequently higher catalytic activity for EG oxidation. This response was attributed to improvement in the synergistic effect provided by the reduction of the amount of Rh and Ni in the ternary alloy when compared to Pt80Rh15Ni5/C and Pt/C ETEK electrocatalysts. However, Pt80Rh15Ni5/C electrocatalyst showed greater tolerance to poisoning by intermediate species due to the presence of Rh in greater quantity, leading to a formation of adsorbed OH species in potentials smaller than those for platinum.

Synthesis and characterization of core-shell PdAu convex nanospheres with enhanced electrocatalytic activity for ethylene glycol oxidation

The design of cost-efficient catalysts for the electrooxidation of liquid fuel is now highly desirable for the commercial application of direct fuel cells. In spired by this, we herein reported our tremendous efforts in the fabrication of core-shell PdAu convex nanospheres via a green method. Different from the previously reported PdAu core-shell nanostructures, the present PdAu convex nanospheres integrated the benefits of core/shell, many granular protuberances, alloy and electronic effect as well as high surface area. All of these favorable properties embody them to exhibit greatly enhanced electrocatalytic activity and long-term stability towards ethylene glycol oxidation as compared with commercial Pd/C. This work emphasizes the significance of shape-controlled of PdAu nanostructures over the electrocatalytic performances for the ethylene glycol oxidation.

One-Pot Synthesis of Nanodendritic PtIr Alloy with High Electrochemical Activity for Ethylene Glycol Oxidation

Nanodendritic Pt-based bimetallic alloys are one promising catalyst with three-dimensional (3D) networks structure composed of integrating branches for electrochemical catalytic reaction. We successfully synthesized dendrites Pt6Ir4 alloy with small size of 20 nm in oleylamine. The dendritic Pt6Ir4 alloy are characterized by high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The electrochemical tests suggest that the as-prepared dendritic Pt6Ir4 alloy exhibits greatly enhanced ethylene glycol oxidation reaction (EGOR) activity than commercial Pt/C with high EGOR mass activity, anti-poisoning and stability.

Bi-modified Pd-based/carbon-doped TiO2 hollow spheres catalytic for ethylene glycol electrooxidation in alkaline medium

Abstract

Bio-directed one-pot synthesis of Pt-Pd alloyed nanoflowers supported on reduced graphene oxide with enhanced catalytic activity for ethylene glycol oxidation

Amino acids with intrinsic affinity to metallic ions can be employed for controllable synthesis of metal nanocrystals with tunable size and morphology, as well as less toxicity. In this work, L-histidine was exploited as a structure-director for in situ controlled growth of bimetallic PtPd alloyed nanoflowers on reduced graphene oxide (RGO-PtPd nanoflowers) by a simple one-pot aqueous approach at room temperature. There was no seed, template, special apparatus or organic solvent involved in the synthetic process. The as-synthesized nanocomposites displayed improved electrocatalytic ability and durability for ethylene glycol oxidation reaction (EGOR) as compared to Pt-RGO, Pd-RGO, commercial PtRu/C, Pt black and Pt/C catalysts.

One-pot synthesis of platinum–palladium–cobalt alloyed nanoflowers with enhanced electrocatalytic activity for ethylene glycol oxidation

In this work, three-dimensional trimetallic Pt–Pd–Co alloyed nanoflowers are fabricated by a facile one-pot solvothermal strategy, with the assistance of oleylamine as the solvent, surfactant, and reducing agents, along with cetylpyridinium chloride (CPC) as the co-surfactant and shape-directing agents. Their morphology and crystal structure were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning transmission electron microscope (STEM), and X-ray photoelectron spectra (XPS) in details. The respective electrochemically active surface area (ECSA) is estimated to be 32.53m2g−1, and current density is 132.91mAcm−2 for the electrooxidation of ethylene glycol (EG). These values are much higher than those of PtPdCo nanoparticles, PtPd nanoparticles, commercial Pt black, and Pd black under the identical conditions, showing the improved catalytic activity of Pt–Pd–Co nanoflowers. The excellent performances are attributed to the specific structure and synergistic interactions of the trimetallic alloy. The as-prepared nanoflowers can serve as a promising electrocatalyst in fuel cells.

One-pot synthesis of reduced graphene oxide supported hollow Ag@Pt core–shell nanospheres with enhanced electrocatalytic activity for ethylene glycol oxidation

In this study, a simple, facile and one-pot solvothermal method was developed for preparation of reduced graphene oxide (RGO) supported hollow Ag@Pt core–shell nanospheres (hAg@Pt), using ethylene glycol (EG) as a reducing agent and sodium dodecyl sulfate (SDS) as a soft template. Control experiments demonstrated that the molar ratios of the Pt–Ag precursors, the amount of SDS, the presence of RGO, and the reaction temperature were critical to the final nanocomposites. The as-prepared hAg@Pt–RGO showed the improved electrocatalytic activity and durability toward ethylene glycol oxidation, which can serve as a promising potential electrocatalyst in direct alcohol fuel cells.

J061055 エチレングリコールを用いたアルカリ形燃料電池における反応活性の第一原理計算による検討(〔J061-05〕燃料電池・二次電池におけるナノ・マイクロ現象とマクロ性能(5):各種電池)

To develop the inexpensive non-noble highly-active and selective catalyst of the alkaline fuel cell (AFC), we investigated ethylene glycol oxidation on transition metal surfaces such as Fe(001), Co(0001), and Ni(111) based on first principles calculation. To clarity which surface has high activity for ethylene glycol oxidation, we calculate the activation energies for O-H and C-H bond dissociations on all surfaces. Then, we find the lowest activation energies for O-H and C-H bond dissociations on Fe(001). We also calculate the activation energies for C-C bond dissociations on Fe(001) and Ni(111) to reveal the selectivity of the catalyst. The comparison among the activation energies for O-H, C-H, and C-C bond dissociations shows the higher selectivity for the ethylene glycol oxidation on Fe(001) than that on Ni(111). Thus, Fe(001) is expected for the highly-active and selective catalytic material of the AFC.

Ethylene glycol electrooxidation on carbon supported Pt, PtRu and Pt 3Sn catalysts—A comparative DEMS study

We present results of a comparative study on the interaction of ethylene glycol (EG) with carbon supported Pt, PtRu and Pt 3Sn nanoparticle catalysts, employing electrochemical and quantitative differential electrochemical mass spectroscopy (DEMS) measurements under continuous reaction and continuous electrolyte flow conditions. For all three catalysts EG adsorption is inhibited at very cathodic adsorption potentials, dissociative adsorption starts above 0.06 V and increases with increasing potential. Based on the electron yield per formed CO 2 molecule and on the similarity with the CO ad stripping characteristics CO ad is identified as the main stable adsorbate; the relative coverage in terms of adsorbed C1 species, relative to that of a saturated CO adlayer on the respective catalyst, reaches a maximum of ca. 0.6 at around 0.4 V on Pt/Vulcan, ca. 0.2 at around 0.2 V on PtRu/Vulcan and ca. 0.4 at around 0.35 V on Pt 3Sn/Vulcan. Bulk EG electrooxidation under steady-state conditions shows a very small current efficiency for CO 2 formation of below 6% for 0.1 M EG on all three catalysts, the oxidation of EG mainly generates partly oxidized C2 by-products. Catalyst modification by Ru or Sn improves the activity for EG oxidation at low potentials (≤0.56 V), but does not lead to better selectivities for complete EG oxidation to CO 2 at potentials with significant oxidation rates. Hence, C–C bond breaking is rate limiting for complete oxidation under present reaction conditions for all three catalysts. The data are consistent with a parallel pathway reaction mechanism, with formation and subsequent oxidation of CO ad in the one pathway and partial oxidation, via a sequence of reaction steps, to increasingly oxidized C2 species in the other pathway.

Electrocatalytic properties of Pt(111), Pt(332), Pt(331) and Pt(110) single crystal electrodes towards ethylene glycol oxidation in sulphuric acid solutions

In the present paper four platinum single crystal electrodes, two basal planes of Pt(111) and Pt(110) and two stepped surfaces of Pt(332) and Pt(331), were prepared and used in the study of electro-oxidation of ethylene glycol (EG). All of these Pt single crystal electrodes belong to the [1 1 0] zone of crystallography, and exhibit on their surface (111) symmetry sites or certain combinations of terraces of (111) symmetry with steps of (111) symmetry type. It has been found that as a result of a favourable steric matching of surface sites the Pt(110) electrode manifested a higher activity both for EG dissociative adsorption and oxidation than that of the Pt(111) electrode. The stepped surfaces of Pt(332) and Pt(331) operated with certain combinations of characteristics of Pt(111) and Pt(110). The best electrocatalytic properties have been obtained with a Pt(331) electrode, and this is attributed both to the configuration of the atomic arrangement and to the stability of this surface. In summary, the above results show that the performance of a given Pt single crystal electrode in EG oxidation at a potential below 1.0 V may be evaluated by three factors. 1. (1) The ability to resist self-poisoning (AB) which describes the difficulty of EG dissociative adsorption on the electrode surface. 2. (2) The activity for EG oxidation (AC). In considering that the threshold potential for EG oxidation on all electrodes is at 0.3 V and that the self-poisoning is encountered in PGPS, the activity for EG oxidation may be reasonably characterized by the intensity of the peak current acquired in NGPS near 0.6 V, which corresponds to the maximum current of EG oxidation on an activated (non-poisoned) surface of the electrode. 3. (3) The stability of activity during potential cycling (SA) between 0.05 and 1.0 V, which describes the resistance to the decrease of intensity of the EG oxidation current during voltammetric cycling. For the two basal planes studied, the AB and SA of Pt(111) are higher than those of Pt(110), but its AC is much lower than that of Pt(110). These differences are clearly related to the surface atomic arrangement of the two electrodes. As has been discussed above, the surface of Pt(111) is atomically smooth and stable during voltammetric cycling. The surface of Pt(110) presents, however, atomic steps and is reconstructed under experimental conditions, i.e. certain steric configurations are encountered on the Pt(110) surface. The high AC and the low AB may be assigned to a favourite stereographic matching during EG adsorption and oxidation on Pt(110). The two electrodes with stepped surfaces, Pt(332) and Pt(331), contain different densities of (110) sites, which are formed on the border between terrace and step, as shown in Fig. 8. The AB of these two electrodes has been observed at a moderate range between that of Pt(111) and the AB of Pt(110). With a majority of (111) sites on its surface, the electrode of Pt(332) operates at a relatively higher AC than Pt(111) does, and its SA is not as good as that of Pt(111) but is much better than the SA of a Pt(110) electrode. In all cases the highest AC and SA are obtained with a Pt(331) electrode. It may be seen from the profile of a (331) plane (shown by the cross-section of A-A in Fig. 8) that all atoms on the top of the surface participated in forming (110) sites, and the atom on the step has two functions — one is to form a (110) site with an atom located in the terrace of second layer and the other is to form a (111) site in the terrace of the same layer. It has been mentioned in the above discussions that the Pt(110) electrode keeps a higher AC due to favourite stereographic matching in EG adsorption and oxidation, but its SA is the worst, due to the instability of the surface. The highest AC and SA obtained with Pt(331) may be ascribed not only to the high density of (110) sites existing on the surface, but also to the stabilization of these (110) sites, and moreover, the synergy generated by the atomic arrangement of the Pt(331) surface may also contribute to the performance of the Pt(331) electrode.

Electrolytically co-deposited platinum—palladium electrodes and their electrocatalytic activity for ethylene glycol oxidation: a synergistic effect

The electrocatalytic oxidation of ethylene glycol has been investigated on platinumpalladium alloy electrodes of different compositions in alkaline aqueous solution. The surface characteristics of the alloys in contact with electrolytic solution have been studied using cyclic voltammetry. X-ray diffraction studies are interpreted to verify homogeneity of electrolytically co-deposited alloys. Enhanced electrocatalytic activity at about 20 at.% in Pd is obtained when compared to pure metals, thus leading to a synergistic effect. An explanation of these effects is suggested on the basis of a decrease of strongly bound residue of ethylene glycol.