Use of Pd-Pt loaded graphene aerogel on nickel foam in direct ethanol fuel cell

A size customized binder-free bimetallic Pd-Pt loaded graphene aerogel deposited on nickel foam plate (Pd-Pt/GA/NFP) was prepared and used as an electrode for an alkaline direct ethanol fuel cell (DEFC) under room temperature. The effect of fuel concentration and metal composition on the output power density of the DEFC was systematically investigated. Under the optimum fuel concentration, the cell could achieve a value of 3.6 mW cm⁻² at room temperature for the graphene electrode with Pd/Pt ratio approaching 1:1. Such results demonstrated the possibility of producing a size customized metal loaded GA/NFP electrode for fuel cell with high performance.     

Performance of Pd Electrocatalyst Supported on a Physical Mixture Indium Tin Oxide–carbon for Glycerol Electro–oxidation in Alkaline Media

Palladium electrocatalysts, supported on Vulcan XC 72 carbon and indium tin oxide (ITO) with different ratios, were prepared by borohydride reduction method and analysed for glycerol electro‐oxidation application in the presence of KOH solution. Transmission electron microscopy (TEM) and X‐ray diffraction (XRD) techniques were used to characterize the particle size and crystal electrocatalyst structures, whereas their catalytic activities regarding the glycerol electro‐oxidation were evaluated by cyclic voltammetry (CV), chronoamperometry and tested in a direct alkaline glycerol fuel cell (DGFC) by electrochemical techniques. Micrographs results showed that the ITO presence promotes a large agglomeration of particles. Pd/C–ITO electrocatalysts showed peaks associated with the face‐centered cubic (fcc) structure of palladium and several others peaks associated with ITO used as support. Similar performance was found on all Pd/C–ITO electrocatalysts where measurements in CV were compared to Pd/C and Pd/ITO with Pd/C–ITO 50:50 chronoamperometry, presenting a better performance for glycerol electro‐oxidation. When using Pd/C–ITO 85:15 electrocatalyst and 1.0 mol L⁻¹ glycerol at 90 °C, the maximum power density found was 2,1 times higher than that obtained using Pd/C and Pd/CITO electrocatalysts. Therefore, the physical mixture of ITO and carbon, to be used as a support improves the electrocatalytic activity for glycerol oxidation reaction.     

柴油深度脱芳烃Pd-Pt/USY催化剂的EXAFS研究

为满足日趋严格的环保要求和适应汽车工业的快速发展,柴油深度脱芳烃已成为国内外普遍关注的课题．近年来的研究表明,Pd－Pt/USY催化剂具有较高的芳烃加氢活性和较强的耐硫中毒能力[’－     

炭载Pd-Pt催化剂中Pd和Pt原子比对直接甲醇燃料电池阴极催化性能的影响

研究了不同Pd和Pt原子比的炭载Pd-Pt(Pd-Pt/C)催化剂对氧还原的电催化性能和抗甲醇性能。 发现当Pd和Pt原子比从20∶0增加至17∶3时,Pd-Pt/C催化剂对氧还原的电催化活性逐步增加,而对甲醇氧化均元电催化活性,表明有很好的抗甲醇能力。 但当Pd和Pt原子比增加至16∶4时,虽然对氧还原的电催化活性还在增加,但抗甲醇能力下降。 所以当Pd-Pt原子比为17∶3时,Pd-Pt/C有很好的对氧还原的电催化性能和抗甲醇能力,可以用作直接甲醇燃料电池(DMFC)的阴极催化剂。     

One-pot fabrication of single-crystalline octahedral Pd-Pt nanocrystals with enhanced electrocatalytic activity for methanol oxidation

This study reports the synthesis of octahedral Pd-Pt bimetallic alloy nanocrystals through a facile, one-pot, templateless, and seedless hydrothermal method in the presence of glucose and hexadecyl trimethyl ammonium bromide. The morphologies, compositions, and structures of the Pd-Pt nanocrystals were fully characterized by various physical techniques, thereby demonstrating their highly alloying octahedral nanostructures. The formation or growth mechanism of the Pd-Pt bimetallic alloy nanocrystals was explored and is discussed here based on the experimental observations. In addition, the synthesized Pd-Pt nanocrystals were applied to the methanol oxidation reaction (MOR) in alkaline media, which proved that the as-prepared catalysts exhibit enhanced electrocatalytic activity for MOR. Pd₁Pt₃ exhibited the best stability and durability, and its mass activity was 3.4 and 5.2 times greater than those of Pt black and Pd black catalysts, respectively. The facile synthetic process and excellent catalytic performance of the as-prepared catalysts demonstrate that they have the potential to be used in direct methanol fuel cell techniques.     

Pd-based PdPt(19:1)/C electrocatalyst as an electrode in PEM fuel cell

A carbon supported Pd-based PdPt catalyst with a Pd:Pt atomic ratio of 19:1 was synthesized and applied to a polymer electrolyte membrane fuel cell (PEMFC). Three different types of single cells with the electrodes containing (PdPt/C:Pt/C), (Pt/C:PdPt/C) and (PdPt/C:PdPt/C) as their anode and cathode electrocatalysts were fabricated and the performance of them was compared. The single cell using PdPt/C as the anode electrocatalyst showed a high performance comparable to the cell with a commercial Pt/C electrocatalyst. This indicates that Pd-based electrocatalysts can be used as an anode electrocatalyst in PEMFC with very small amount of Pt (just about 5 at.%).     

贵金属催化p-叔丁基-α-甲基肉桂醛加氢

采用傅里叶变换红外光谱仪(FT-IR)、N₂吸脱附、X射线衍射(XRD)、透射电子显微镜(TEM)揭示了微波辅助-KOH处理对活性炭的物理化学性能的影响规律。 结果表明,活性炭表面的含氧基团的种类增加,微孔明显减少,中大孔的比例增大。 通过浸渍-原位还原方法制备了Pt、Pd、Ru、Rh负载微波辅助-KOH处理活性炭催化剂,并对其催化p-叔丁基-α-甲基肉桂醛选择性加氢性能进行了研究。 发现Pt具有优异的C=O加氢选择性,而Pd具有优良的C=C加氢选择性。 进一步研究了Pd-Pt双组分催化剂催化p-叔丁基-α-甲基肉桂醛加氢产物分布,随着Pt含量的增加, C=O选择性逐步提高, C=C选择性逐渐下降,且当m(Pd)∶m(Pt)=4∶1时,其催化剂的催化性能最佳。     

pH-effect on oxygen reduction activity of Fe-based electro-catalysts

Recently, our group reported on an innovative synthesis of Fe/N/C-catalysts that considerably increased their activity for the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). This work investigates the ORR-activity in 0.1 M KOH and 0.1 M HClO₄ of one such new Fe/N/C-catalyst prepared by ball-milling and compares it to that of a former Fe/N/C-catalyst prepared by impregnation and to that of 46 wt% Pt/C.At pH 13, the volumetric activities at 0.9 V vs. RHE of the ball-milling Fe/N/C-catalyst, the impregnation Fe/N/C-catalyst and 46 wt% Pt/C are 3.2, 0.3 and 14.8 A cm⁻³, respectively. The ball-milling Fe/N/C-catalyst is promising for alkaline fuel cells.     

Evaluation of Pt40Pd60/MWCNT electrocatalyst as ethylene glycol-tolerant oxygen reduction cathodes

Pt–Pd/MWCNT with Pt:Pd atomic ratio 40:60 and Pt/MWCNT electrocatalyst were synthesized and evaluated as oxygen reduction reaction (ORR) cathodes for Direct Ethylene Glycol Fuel Cells (DEGFC) applications. As reference, a commercial Pt/C material was also tested. We found that Pt–Pd/MWCNT has high tolerance capability to EG and higher selectivity for the ORR compared to the Pt-alone materials. As a result, the shift in onset potential for the ORR, E_onset, at Pt–Pd/MWCNT was considerably smaller than the shift at Pt/MWCNT or Pt/C. The average particle size (from XRD) was 3.5 and 4 nm for Pt/MWCNT and Pt–Pd/MWCNT, respectively. A moderate degree of alloying was determined for the Pt–Pd material. An advantageous application of Pt–Pd electrocatalysts should be in DEGFCs.     

Electrocatalytic activity of binary Palladium Ruthenium anode catalyst on Ni-support for ethanol alkaline fuel cells

In search for a cheaper anode catalyst for the oxidation of ethanol for development of direct alcohol fuel cells, Pd has been considered here as an interesting substitute for Pt in Pt Ru binary electrodeposite. The binary catalyst when co-deposited on nickel support has been found to increase the current density and decrease the anodic overvoltage significantly with respect to pure Pt, Pd and Ni. Its electrocatalytic capability is also comparable with that of the Pt-Ru binary electrocatalyst on Ni-support, when studied in 1 M EtOH containing 1 M NaOH solution. The effect of loading of Pd Ru electrocatalyst on Ni support has also been tested. The electrocatalytic activity of the electrodes for oxidation of ethanol has been explained by studies of cyclic voltammetry, chronopotentiometry, steady-state polarization, and conjugated scanning electron microscopy–energy dispersion X-ray spectroscopy. It has been found that electrode containing the higher amount of deposit are less affected by carbonaceous poisons.     

Oxygen reduction reaction on the low index planes of palladium electrodes modified with a monolayer of platinum film

Oxygen reduction reaction (ORR) has been studied on the low index planes of Pd modified with a monolayer of Pt (Pt/Pd(hkl)) in 0.1 M HClO₄ with the use of hanging meniscus rotating disk electrode. The activity for ORR on bare Pd(hkl) electrode depends on the surface structure strongly, however, voltammograms of ORR on Pt/Pd(hkl) electrodes do not depend on the crystal orientation. The specific activities of Pt/Pd(hkl) electrodes at 0.90 V (RHE) are higher than that on Pt(1 1 0) which has the highest activity for ORR in the low index planes of Pt. The mass activity on Pt/Pd(hkl) electrode is 7 times as high as a commercial Pt/C catalyst.     

电沉积制备钯铂电极上乙醇的电催化氧化

研究了乙醇在碱性介质（１．０ｍｏｌ．Ｌ＾－１ＮａＯＨ）中电沉积制备的Ｐｂ／ＧＣ、Ｐｔ／ＧＣ和Ｐｄ－ｐｔ／ＧＣ电极上的电催化氧化,实验结果表明：由此法制备的钯铂系列合金电极对乙醇的电催化氧化表现出明显的协同效应－乙醇的含钯原子分数ｙｐｄ＝０．３３６的ｐｄ－ｐｔ／ＧＣ合金电极上的节极交换电流密度是其在纯铂电极上的３０多倍。     

Platinum submonolayer-monolayer electrocatalysis: An electrochemical and X-ray absorption spectroscopy study

A new Pt monolayer electrocatalyst concept is described and the results of electrochemical and X-ray absorption spectroscopy (XAS) studies are presented. Two new methods that facilitate the application of this concept in obtaining ultra-low-Pt-content electrocatalysts have been developed. One is the electroless (spontaneous) deposition of a Pt submonolayer on Ru nanoparticles, and the other is a deposition of a Pt monolayer on Pd nanoparticles by redox displacement of a Cu adlayer. The Pt submonolayer on Ru (PtRu₂₀) electrocatalyst demonstrated higher CO tolerance than commercial catalysts under conditions of rotating disk experiments. The long-term stability test showed no loss in performance over 870 h using a fuel cell operating under real conditions, even though the Pt loading was approximately 10% of that of the standard Pt loading. In situ XAS indicated an increase in d-band vacancy of deposited Pt, which may facilitate partly the reduced susceptibility to CO poisoning for this catalyst. The kinetics of O₂ reduction on a Pt monolayer on Pd nanoparticles showed a small enhancement in comparison with that from a Pt nanoparticle electrocatalyst. The increase in catalytic activity is partly attributed to decreased formation of PtOH, as shown by XAS experiments.     

Synthesis of Pd-Cu Bimetallic Electrocatalyst for Ethylene Glycol and Glycerol Oxidations in Alkaline Media

PdCu/C (XC-72) electrocatalyst was synthesized by a chemical reduction method using ethylene glycol as reaction media, polyvinylpyrrolidone as surfactant and sodium borohydride as reducing agent. Vulcan carbon XC-72 was employed as support and added through the PdCu synthesis procedure; further, Pd commercial (Pd/C, 20% ETEK) was used for comparison purposes. Physicochemical characterization consisted in XRD, XRF, EDS and TEM analyses. TEM micrographs showed the presence of semi-spherical nanoparticles with a particle distribution around 6 nm. X-ray diffraction patterns showed the typical face-centered cubic structure of Pd materials for commercial Pd and revealed a low crystallinity for PdCu/C. The XRF analysis showed a mass metal composition of 81% Pd and 19% Cu. EDS analysis was made to single particles exhibiting an average elemental composition of 92% Pd and 8% Cu. The electrocatalytic activity of PdCu/C and Pd/C was evaluated by cyclic voltammetry experiments toward ethylene glycol and glycerol oxidations using three concentrations (0.1, 1 and 3 M) and 0.3 M KOH as electrolyte. These experiments exhibited the superior performance of PdCu compared with commercial Pd by means of current densities associated to the electro-oxidation reactions where values at least 3-fold higher than Pd/C were found.     

电沉积制备钯铂电极上乙醇的电催化氧化

研究了乙醇在碱性介质（１．０ｍｏｌ·Ｌ－１ＮａＯＨ）中电沉积制备的Ｐｄ／ＧＣ、Ｐｔ／ＧＣ和Ｐｄ．Ｐｔ／ＧＣ电极上的电催化氧化．实验结果表明：由此法制备的钯铂系列合金电极对乙醇的电催化氧化表现出明显的协同效应─—乙醇在含把原子分数ｙｐｂ＝０．３３６的Ｐｄ－Ｐｔ／ＧＣ合金电极上的阳极交换电流密度是其在纯铂电极上的３０多倍．     

Synthesis of coin-like hollow carbon and performance as Pd catalyst support for methanol electrooxidation

The coin-like hollow carbon (CHC) has been synthesized by only using ethanol as the carbon source with a novel Mg/NiCl₂ catalytic system via a facile solvothermal method for the first time. The CHC synthesized at optimized conditions shows an average thickness of less than 154 nm and the coin diameter of 1–3 μm. The CHC is characterized by SEM, TEM, XRD and electrochemical techniques. Pd on CHC (denotes as Pd/CHC) electrocatalysts are prepared for methanol oxidation in alkaline media. The Pd/CHC electrocatalyst gives a mass activity of 2930 A g⁻¹ Pd for methanol oxidation against 870 A g⁻¹ Pd on Pd/C electrocatalyst. One main reason for the higher mass activity of the Pd/CHC is the higher electrochemical active surface area (EASA) of the Pd/CHC.     

Iodinated carbon materials for oxygen reduction reaction in proton exchange membrane fuel cell. Scalable synthesis and electrochemical performances

Doped graphene-based cathode catalysts are considered as promising competitors for ORR, but their power density has been low compared to Pt-based cathodes, mainly due to poor mass-transport properties. A new electrocatalyst for PEMFCs, an iodine doped grahene was prepared, characterized, and tested and the results are presented in this paper. We report a hybrid derived electrocatalyst with increased electrochemical active area and enhanced mass-transport properties. The electrochemical performances of several configurations were tested and compared with a typical Pt/C cathode configuration. As a standalone catalyst, the iodine doped graphene gives a performance with 60% lower than if it is placed between gas diffusion layer and catalyst layer. If it is included as microporous layer, the electrochemical performances of the fuel cell are with 15% bigger in terms of power density than the typical fuel cell with the same Pt/C loading, proving the beneficial effect of the iodine doped graphene for the fuel cell in the ohmic and mass transfer region. Moreover, the hybrid cathode manufactured by commercial Pt/C together with the material with best proprieties, is tested in a H₂-Air fuel cell and a power density of 0.55 W cm⁻² at 0.52 V was obtained, which is superior to that of a commercial Pt-based cathode tested under identical conditions (0.46 W cm⁻²).     

聚酰亚胺上催化剂增强化学气相沉积钯-铂双层膜

 以N2和O2为载气,采用催化剂增强化学气相沉积法于聚酰亚胺上获得了Pt和Pd-Pt双层金属薄膜. 当使用Pd(hfac)2和PtMe2(COD)为前驱体,在同一反应器内共沉积时,只有Pt被沉积. 金属Pd和Pt顺序沉积可形成Pd-Pt双层膜.     

Pd/Pt core–shell nanowire arrays as highly effective electrocatalysts for methanol electrooxidation in direct methanol fuel cells

Highly ordered Pd/Pt–core–shell nanowire arrays (Pd/Pt NWAs) have been prepared by anodized aluminum oxide (AAO) template-electrodeposition and magnetron sputtering methods. Pd/Pt NWA electrode shows a very high electrochemical active surface area and high electrocatalytic activity for the methanol electrooxidation in acid medium for direct methanol fuel cells (DMFCs). The mass specific anodic peak current density is 756.7 mA mg⁻¹ Pt for the methanol oxidation on the Pd/Pt NWA electrode, an increase by a factor of four as compared to conventional E-TEK PtRu/C electrocatalysts. The mechanism of the significant enhancement of the Pd/Pt core/shell NWA nanostructure in the efficiency and electrocatalytic activity of Pt for the methanol electrooxidation in acid medium is discussed.     

Synthesis and electrocatalytic activity of Au/Pt bimetallic nanodendrites for ethanol oxidation in alkaline medium

Gold/Platinum (Au/Pt) bimetallic nanodendrites were successfully synthesized through seeded growth method using preformed Au nanodendrites as seeds and ascorbic acid as reductant. Cyclic voltammograms (CVs) of a series of Au/Pt nanodendrites modified electrodes in 1M KOH solution containing 1M ethanol showed that the electrocatalyst with a molar ratio (Au:Pt) of 3 exhibited the highest peak current density and the lowest onset potential. The peak current density of ethanol electro-oxidation on the Au(3)Pt(1) nanodendrites modified glassy carbon electrode (Au(3)Pt(1) electrode) is about 16, 12.5, and 4.5 times higher than those on the polycrystalline Pt electrode, polycrystalline Au electrode, and Au nanodendrites modified glassy carbon electrode (Au dendrites electrode), respectively. The oxidation peak potential of ethanol electro-oxidation on the Au(3)Pt(1) electrode is about 299 and 276 mV lower than those on the polycrystalline Au electrode and Au dendrites electrode, respectively. These results demonstrated that the Au/Pt bimetallic nanodendrites may find potential application in alkaline direct ethanol fuel cells (ADEFCs).