Performance For Ethanol Oxidation Research Articles

Influence of Pd-doping concentration on activity and CO anti-poisoning ability of PtPd/GNRs alloy catalyst for ethanol oxidation and density functional theory analysis

Graphene nanoribbons decorated with noble metal nanoparticles possess great catalytic performance for ethanol oxidation in direct ethanol fuel cells. Herein, PtPd alloy catalysts supported on graphene nanoribbons are researched, and an appropriate Pt–Pd component with the mole ratios of 0.46:0.54 is found to possess excellent catalytic activity and durability. Moreover, the density functional theory analysis shows that the composite catalyst with Pt:Pd ratio of 1:1 owns the highest negative electronic property and the high adsorption energy to restrict CO adsorption. The great CO anti-poisoning ability may be the main reason for the excellent catalytic performance of Pt0.46Pd0.54/GNRs catalyst.

Correlation of Surface Ag Content in AgPd Shells of Ultrasmall Core–Shell Au@AgPd Nanoparticles with Enhanced Electrocatalytic Performance for Ethanol Oxidation

We report the synthesis of well-dispersed, ultrasmall, core–shell (CS) Au@AgPd nanoparticles (NPs) via galvanic reaction of Ag shells of CS Au@Ag NPs with Pd2+ ions at room temperature. It is found that Ag content in the resulting AgPd shells is dependent mainly on the thickness of the original Ag shells and the concentrations of Pd2+ ions used for the galvanic reaction. In addition, the electrocatalytic performance of the resulting CS Au@AgPd NPs is dependent on the surface Ag content (s-AgnPd1–n) in the AgPd shells (where s-AgnPd1–n is added to highlight the surface Ag content) while being independent of the total Ag content. When the ultrathin AgPd shells with 0.79 nm thickness and the surface Ag content of about 29.4% are formed on ca. CS0.60 Au@Ag NPs, the resulting CS0.60 Au@AgPd-s-Ag0.294Pd0.706 NPs with average size of 8.5 nm have significantly increased electrochemically active surface area (up to 77.5 m2 g–1) and exhibit superior catalytic activity (1.16 A mgPd–1) toward ethanol oxidation (0.50 ...

Facial synthesis of porous hematite supported Pt catalyst and its photo enhanced electrocatalytic ethanol oxidation performance

The porous α-Fe2O3 supported Pt catalyst is synthesized by a facial thermal treatment assisted precipitation method. The particle size of Pt is less than 3nm. The pore diameters of α-Fe2O3 particles are concentrated to 2.46nm in a mesooporous scale. Its electrochemical performance is tested. The ethanol oxidation current of the Pt/Fe2O3 catalsyt obviously improves under illumination, compared with that in the dark, during the optical switching operation. Moreover, with the addition of α-Fe2O3, the ethanol oxidation current of Pt/C grows about 51% under illumination and 32% in the dark; the onset potential shifts negtively for about 20mV. This work demostrates an optical strategy which can be a potential alternative to accelerate electrode reactions towards ethanol oxidation reaction.

Biomolecule-assisted synthesis of porous PtPd alloyed nanoflowers supported on reduced graphene oxide with highly electrocatalytic performance for ethanol oxidation and oxygen reduction

In this work, we have prepared porous PtPd alloyed nanoflowers uniformly supported on reduced graphene oxide by a simple and facile wet-chemical method, with the assistance of cytosine as a structure-directing agent. The products were mainly characterized by transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The as-prepared nanocomposites displayed improved electrocatalytic performances toward ethanol oxidation in alkaline media and oxygen reduction in acidic media, which make it a promising electrocatalyst in fuel cells.

Construction of Dandelion-like Clusters by PtPd Nanoseeds for Elevating Ethanol Eletrocatalytic Oxidation

We successfully synthesized a dandelion-like PtPd heterogeneous structure via a facile one-pot hydrothermal route by reducing Na2PdCl4 and H2PtCl6 with ascorbic acid in the presence of hexadecylpyridinium chloride monohydrate. Hexadecylpyridinium chloride monohydrate acted as the shape-directing agent, which is critical to the reproducible formation of dandelion-like PtPd nanoclusters (DPtPdNC). The prepared DPtPdNC with an average diameter of 40nm composed of dozens of branched arm assembled by Pt and Pd heterogeneous nanoseeds. DPtPdNC had a strong electron-electron interaction. What's more, there were numerous nanoscale steps, kinks and edges in DPtPdNC open channel structure. As a result, an optimized DPtPdNC made by fine-tuning ratio of the Pt (7%) and Pd (93%) showed hugely active surface sites and a superior electrocatalytic performance for ethanol oxidation was well as a long durability.

Size-controllable synthesis of trimetallic RhPdPt island-shaped nanoalloys with enhanced electrocatalytic performance for ethanol oxidation in alkaline medium.

Size-controllable, high-yield, island-shaped RhPdPt trimetallic nanocrystals with sub-2.0 nm islands have been successfully synthesized through a facile aqueous solution approach. The results of X-ray diffraction (XRD), energy-dispersive X-ray (EDX) line scanning and elemental mapping analysis showed the as-synthesized RhPdPt nanocrystals are alloy structures. These island-shaped RhPdPt trimetallic nanoalloys showed a composition-dependent electrocatalytic performance for ethanol oxidation in alkaline medium. Due to the special structure and intermetallic synergies, the Rh10Pd40Pt50 nanoalloys exhibited an enhanced catalytic activity and durability relative to island-shaped Pd50Pt50 bimetallic nanoalloys and commercial Pt black. The peak current density for Rh10Pd40Pt50 nanoalloys was 1.81 and 1.38 times that for commercial Pt black and Pd50Pt50 nanoalloys, respectively. In addition, the peak potential on Rh10Pd40Pt50 nanoalloys decreased 42 mV relative to commercial Pt black and Pd50Pt50 nanoalloys.

Facile one-pot synthesis of Pd–PEDOT/graphene nanocomposites with hierarchical structure and high electrocatalytic performance for ethanol oxidation

Pd–PEDOT/graphene nanocomposites with hierarchical structure and superior electrocatalytic performance toward ethanol oxidation are fabricated by a facile one-pot method.

Ethanol electrooxidation on PdIr/C electrocatalysts in alkaline media: electrochemical and fuel cell studies

PdIr/C electrocatalysts in different atomic ratios (Pd:Ir 90:10, 70:30, and 50:50), Pd/C and Ir/C supported on Vulcan XC 72 carbon were tested for ethanol electrooxidation in alkaline media. The electrocatalysts were prepared by borohydride reduction method. The electrocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), cyclic voltammetry (CV), and chronoamperometry (CA). The XRD measurements suggested the PdIr alloy formation. EDS analyses showed the real atomic ratios similar to the nominal ones. TEM showed the average particle diameter between 4.6 and 5.8 nm for all compositions prepared. The catalytic activity for ethanol electrooxidation in alkaline medium investigated by CV and CA at room temperature showed that PdIr/C (90:10) exhibited higher performance for ethanol oxidation in comparison with others PdIr/C compositions, Pd/C and Ir/C, while the experiments on a single direct ethanol alkaline fuel cell at 70 °C showed higher performance for PtIr (70:30). The best results obtained using PdIr/C electrocatalysts may be associated to the electronic effect between Pd and Ir that might cause a decrease of poisoning on catalyst and the occurrence of bifunctional mechanism.

One-pot synthesis of Au@Pd core-shell nanocrystals with multiple high- and low-index facets and their high electrocatalytic performance.

Bimetallic nanocrystals (NCs) enclosed by high-surface energy facets have been of enormous interest due to their pronounced catalytic performance in numerous chemical and electrochemical reactions. However, it remains a significant challenge to develop a facile method to synthesize bimetallic NCs with high-surface energy facets in the form of finely tuned structures due to the difficulties in manipulating the nucleation and growth kinetics of NCs in the presence of multiple metal precursors. In the present work, a facile one-pot aqueous synthesis method is developed for the production of bimetallic Au@Pd core-shell NCs with an unusual truncated hexoctahedral (THOH) shape without pre-synthesized seeds. The THOH Au@Pd NCs are bound by multiple high- and low-index facets. The formation of this unique structure is realized through co-reduction of Au and Pd precursors under precisely controlled kinetic conditions. The prepared THOH NCs exhibit a prominent electrocatalytic performance for ethanol oxidation, which is attributed to their characteristic structural features. This study significantly expands the understanding of NC growth and will lead to fabricating novel nanomaterials with desired morphologies and functions.

Hollow nanoporous Au/Pt core–shell catalysts with nanochannels and enhanced activities towards electro-oxidation of methanol and ethanol

In the work, hollow nanoporous Au/Pt core–shell (H-PtAu) catalysts with nanochannels were prepared with different sizes of gold nanoparticles of a narrow size distribution in the range of 1.8 ± 0.3, 3.2 ± 0.3 and 4.6 ± 0.5 nm. The hollow spheres were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM) and an energy-dispersive X-ray (EDX) analyzer. The electrochemical methods by cyclic voltammetric and chronoamperometry demonstrate that the catalytic performance of hollow nanoporous Au/Pt sphere electrocatalysts increases with the decrease of Au particles size in the samples. The nanoporous hollow structure of the electrocatalysts improves the efficiency for electro-oxidation of methanol and ethanol. More importantly, the nanoporous H-PtAu electrocatalysts have a higher catalytic activity and better steady-state performance for ethanol oxidation than methanol.

Green synthesis of graphene–PtPd alloy nanoparticles with high electrocatalytic performance for ethanol oxidation

A facile and green method is described for the fabrication of PtPd alloy nanoparticles on graphene nanosheets (PtPdNPs/GNs). The keys of the synthesis strategy were to employ a low-cost and green solvent, ethanol, as the reductant, and a two-dimensional carbon material, GNs, as the supporting material. The morphology, structure and composition of the as-prepared PtPdNPs/GNs were characterized by transmission electron microscopy (TEM), high resolution TEM, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. It was found that by changing the preparation procedures and varying the molar ratio of the starting precursors, NPs with different shapes such as spherical NPs (Pt1Pd1NPs), nanoflowers (Pd@PtNFs) and nanodentrites (Pt3Pd1NPs) could be produced on GNs. Based on these observations, a plausible growth mechanism of PtPdNPs/GNs was discussed. In addition, the electrocatalytic properties of PtPdNPs/GNs for direct ethanol oxidation in alkaline media were systematically investigated. Due to the synergetic effects of Pt and Pd, and the enhanced electron transfer properties enhanced of GNs, PtPdNPs/GNs exhibited higher electrocatalytic ability and better tolerance to reaction intermediate poisoning in the electrooxidation of ethanol compared with Pt nanoflowers supported on GNs (PtNFs/GNs), PdNPs/GNs and PtPdNPs supported on carbon black (PtPdNPs/C). The presented method is a general, facile and green approach for the synthesis of GN-supported bimetallic PtM electrocatalysts, which is significant for the development of high performance electrocatalysts.

Ni-substituted LaMnO3 perovskites for ethanol oxidation

The B-site substitution of LaMnO3 perovskites by Ni was investigated under the oxidation of ethanol. Proper characterization techniques, including BET surface area measurement, XRD, FTIR, XPS, TPR, O2-TPD, and FE-SEM experiments were performed to survey the physicochemical properties of perovskites. The results reveal that up to 25% of Mn can be replaced by Ni; beyond this limit, segregated NiOx can be synthesized. Inserting Ni into the solid solution of perovskite yields unique bridging lattice oxygen sites (Ni–O–Mn) in Ni-doped LaMnO3. Based on catalytic performance in ethanol oxidation, the Ni–O–Mn sites are likely to promote ethanol conversion and the oxidation of acetaldehyde to CO2 at low reaction temperatures. The abatement of intermediates over Ni–O–Mn sites is hypothesized and a plausible reaction pathway is proposed. Moreover, the time on-stream testing revealed that the interaction between Ni and Mn is likely to enhance perovskite's thermal stability in ethanol oxidation.

The activity of ALD-prepared PtCo catalysts for ethanol oxidation in alkaline media

Controlled bimetallic catalyst materials can be obtained using atomic layer deposition (ALD) method. In this paper, this method was applied to prepare Pt, PtCo, and PtCoPt nanoparticle catalysts on carbon support. Their activity for ethanol oxidation was studied by various electrochemical methods and the dependency of the reaction on temperature and mass transfer was evaluated. In addition, FTIR analysis was performed to confirm the reaction products. The results showed that bimetallic PtCo enhances ethanol oxidation by increasing the amount of CO2 produced; however, at elevated temperatures, the bimetallic PtCo catalyst lacked stability. Nevertheless, the ALD-prepared PtCoPt catalyst showed similar reaction mechanism as PtCo catalyst, but possess increased stability and superior performance for ethanol oxidation at elevated temperatures.

In situ synthesis of palladium nanoparticle on functionalized graphene sheets at improved performance for ethanol oxidation in alkaline media

Dimethyldiallylammonium chloride (DMDAAC) modified reduced graphene oxide supported Pd nanoparticles (Pd/DMDAAC-RGO) were fabricated by polyol microwave heating method. The Pd/DMDAAC-RGO hybrid were characterized by transmission electromicroscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) analysis and electrochemical tests. High Pd metal loadings, up to 80wt. % with a mean size of 1.8nm, were densely in situ decorated on DMDAAC-modified RGO surfaces. Compared with traditional carbon-based Pd catalysts, Pd/DMDAAC-RGO exhibits better activity and stability for ethanol oxidation in alkaline media with the same Pd content on the electrode. This improved activity indicates that DMDAAC plays a crucial role in the dispersion and stabilization of Pd nanoparticles on RGO sheets and DMDAAC-RGO are able to an alternative support for Pd immobilization in direct ethanol fuel cells and other catalytic devices.

Electro-Oxidation of Ethanol on PtSnRh/C-Sb2O5·SnO2 Electrocatalysts Prepared by Borohydride Reduction

PtSnRh/C-Sb2O5·SnO2 (90:05:05, 70:25:05, and 50:45:05) electrocatalysts were prepared in a single step using H2PtCl6·6H2O, SnCl2·2H2O, RhCl3·xH2O as metal sources, sodium borohydride as reducing agent and a physical mixture of 85 % Vulcan Carbon XC72 and 15 % Sb2O5·SnO2 (antimony tin oxide—ATO) as support. The materials prepared were firstly characterized by X-ray diffraction (XRD), transmission electron microscopy. XRD showed peaks characteristic of Pt face-centered cubic structure and several others peaks associated with SnO2 and ATO, while studies showed the metal nanoparticles homogeneously distributed over the supports with average particle sizes of 2 nm for all electrocatalysts. The catalytic activity for ethanol electro-oxidation in acid medium was investigated by cyclic voltammetry (CV), chroamperometry (CA), and FTIR measurements at 25 °C. The CV and CA results showed that PtSnRh/C-Sb2O5·SnO2 (70:25:05) electrocatalyst exhibited higher performance for ethanol oxidation in comparison with others PtSnRh/C electrocatalysts prepared, while FTIR measurements showed that acetic acid, acetaldehyde, and CO2 are preferentially formed for all electrocatalysts. However, PtSnRh/C-Sb2O5·SnO2 (70:25:05) electrocatalyst showed a production of acetic acid and CO2 superior to the others prepared. This result could be associated with the higher performance observed for ethanol oxidation.

A UPD-spontaneous redox approach to the preparation of monolayer palladium on reduced graphene oxide-supported gold nanoparticles for ethanol electrooxidation in alkaline media

Abstract Monolayer Pd on electrochemical-reduced graphene oxide supported Au nanoparticles (m-Pd–Au/ERG) was designed by a simple and effective route, which produces electrocatalyst with a considerably low Pd loading and good electrocatalytic performance for ethanol oxidation. The as-prepared m-Pd–Au/ERG nanocompostie was characterized by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The results show that high-density m-Pd–Au nanoparticles are dispersed on the surface of ERG uniformly. The electrochemical activities of the as-prepared nanocomposites toward ethanol oxidation in alkaline media were investigated by using cyclic voltammetry and chronoamperometric technique. The results demonstrate that the m-Pd–Au/ERG catalyst shows much higher electrocatalytic activity, stronger tolerance to CO than the m-Pd–Au and b-Pd–Au/ERG catalysts for ethanol oxidation.

Preparation of PtSnRh/C-Sb2O5·SnO2 electrocatalysts by an alcohol reduction process for direct ethanol fuel cell

PtSnRh/C-Sb2O5·SnO2 electrocatalysts with different Pt/Sn/Rh atomic ratios (90:05:05, 70:25:05, and 50:45:05) were prepared by an alcohol reduction process using H2PtCl6·6H2O, SnCl2·2H2O, RhCl3·xH2O as metal sources, ethylene glycol as solvent and reducing agent, and a physical mixture of Vulcan XC72 (85 wt%) and Sb2O5·SnO2 (15 wt%) as support. The electrocatalysts were characterized by X-ray diffraction and transmission electron microscopy. The electro-oxidation of ethanol was studied by cyclic voltammetry and chronoamperometry at 25 and 50 °C and in single direct ethanol fuel cell (DEFC) at 100 °C. The diffractograms of PtSnRh/C-Sb2O5·SnO2 electrocatalysts showed the peaks characteristic of Pt face-centered cubic structure and several others peaks associated with ·SnO2 and Sb2O5·SnO2. Transmission electron micrographs of PtSnRh/C-Sb2O5·SnO2 electrocatalysts showed the metal nanoparticles distributed on the supports with particle sizes of about 2–3 nm. The electrochemical measurements and the experiments in a single DEFC showed that PtSnRh/C-Sb2O5·SnO2 (90:05:05) and PtSnRh/C-Sb2O5·SnO2 (70:25:05) electrocatalysts exhibited higher performance for ethanol oxidation in comparison with PtSnRh/C electrocatalyst.

Preparation, characterization and application of Pt–Ru–Sn/C trimetallic electrocatalysts for ethanol oxidation in direct fuel cell

This work aimed to develop a method for the preparation of carbon-supported platinum nanocatalysts modified with Ruthenium and Tin, which were then evaluated for ethanol eletrooxidation in direct fuel cells. The Pechini method was employed to obtain these catalysts. This method consists in the decomposition of a polymeric precursor of metal salts. Nanocatalysts containing different Pt/Ru/Sn molar ratios were prepared by keeping the carbon/metal ratio at a constant value of 60/40%. The obtained nanoparticles were physico-chemically characterized by X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and Energy Dispersive X-ray Spectroscopy (EDX). Crystallite size of around 7.0 nm and 5.8 nm were achieved for the bimetallic and trimetallic nanocatalysts, respectively. The experimental composition was close to the nominal one, but the metal particles were not evenly distributed on the carbon surface. Electrochemical characterization of the nanoparticles was accomplished by cyclic voltammetry (CV) and chronoamperometry. High Performance Liquid Chromatography (HPLC) was carried out after ethanol electrolysis for determining the products generated. Acetaldehyde was the main electrolysis product and traces of CO 2 and acetic acid were also detected. Addition of Ru and Sn to the pure Pt nanoelectrocatalyst significantly improved its performance in ethanol oxidation. The onset potential for ethanol electrooxidation was 0.2 V vs. RHE, in the case of the trimetallic nanocatalyst Pt 0.8Ru 0.1Sn 0.1/C, which was lower than that obtained for the pure Pt catalyst (0.45 V vs. RHE).

Preparation of PtSnSb/C by an alcohol reduction process for direct ethanol fuel cell (DEFC)

PtSn/C and PtSnSb/C electrocatalysts (20 wt.% metal loading) were prepared by an alcohol reduction process using H2PtCl6.6H2O, SnCl2.2H2O, and Sb(OOCCH3) as metal sources, ethylene glycol as solvent and reducing agent, and Vulcan XC72 as carbon support. The electrocatalysts were characterized by energy dispersive X-ray analysis, X-ray diffraction, and transmission electron microscopy, while that the performance for ethanol oxidation was investigated by cyclic voltammetry and chronoamperommetry (chrono) at room temperature. The diffractograms of the PtSn/C and PtSnSb/C electrocatalysts showed four peaks associated to Pt face-centered cubic structure and two peaks that were related to a SnO2 phase. For PtSb/C and PtSnSb/C electrocatalysts, no Sb (antimony) peaks corresponding to a metallic antimony or antimony oxide phases were observed. Transmission electron microscopy images showed that the metal particles were homogeneously distributed over the support. The PtSnSb/C (50:45:05) electrocatalyst showed an increase of performance for ethanol oxidation in relation to PtSn/C electrocatalyst at room temperature. In the tests at 100 °C on a single cell of a direct ethanol fuel cell, the maximum power density of PtSnSb/C (50:45:05) electrocatalyst was slightly higher than that of PtSn/C electrocatalyst.

Preparation and characterization of PtRu/C-rare earth using an alcohol-reduction process for ethanol electro-oxidation

PtRu/C (100% C) and PtRu/C-CeO2, PtRu/C-La2O3, PtRu/C-Nd2O3, and PtRu/C-Er2O3 (85% C and 15% rare earth) electrocatalysts were prepared in a single step by an alcohol-reduction process using H2PtCl6 6H2O and RuCl3 xH2O as metal sources, ethylene glycol as solvent and reducing agent, Vulcan XC72 and rare earth (RE) as support. The electrocatalysts were characterized by energy dispersive X-ray, X-ray diffraction, and transmission electron microscopy. The performance for ethanol oxidation was investigated by cyclic voltammetry and chronoamperommetry at room temperature, and studies on the direct ethanol fuel cell were carried at 100 °C. The Pt:Ru atomic ratios were similar to the nominal used in preparation, and the average particle sizes were in the range of 2.0–3.0 nm. All PtRu/C-RE electrocatalysts showed an increase of performance for ethanol oxidation at room temperature and also on a single direct ethanol fuel cell tests in relation to PtRu/C electrocatalyst at 100 °C.