Showing papers on "Direct methanol fuel cell published in 2012"
TL;DR: The results show that the addition of pyridine-functionalized graphene changes the crystallization process of iron-porphyrin in the MOF, increases its porosity, and enhances the electrochemical charge transfer rate of Iron-porPHyrin.
Abstract: Pyridine-functionalized graphene (reduced graphene oxide) can be used as a building block in the assembly of metal organic framework (MOF). By reacting the pyridine-functionalized graphene with iron–porphyrin, a graphene–metalloporphyrin MOF with enhanced catalytic activity for oxygen reduction reactions (ORR) is synthesized. The structure and electrochemical property of the hybrid MOF are investigated as a function of the weight percentage of the functionalized graphene added to the iron–porphyrin framework. The results show that the addition of pyridine-functionalized graphene changes the crystallization process of iron–porphyrin in the MOF, increases its porosity, and enhances the electrochemical charge transfer rate of iron–porphyrin. The graphene–metalloporphyrin hybrid shows facile 4-electron ORR and can be used as a promising Pt-free cathode in alkaline Direct Methanol Fuel Cell.
836 citations
TL;DR: In this paper, a well-dispersed Pd nanoparticles supported on low-defect graphene (LDG) sheets are successfully prepared by a soft chemical method, which can efficiently avoid damaging the graphene framework in the composite because it does not require cumbersome oxidation of graphite in advance and needs no subsequent reduction of the LDG sheets due to the lower oxidation degree.
Abstract: Well-dispersed Pd nanoparticles supported on low-defect graphene (LDG) sheets are successfully prepared by a soft chemical method. Our approach can efficiently avoid damaging the graphene framework in the composite because it does not require cumbersome oxidation of graphite in advance and needs no subsequent reduction of the LDG sheets due to the lower oxidation degree. Morphology observations show that the Pd nanoparticles with diameters ranging from 1 to 5 nm are evenly deposited on graphene sheets. Raman spectroscopic analysis results reveals that there is only a very small amount of graphene defects in the hybrid. No matter whether it is for a direct formic acid fuel cell (DFAFC) or direct methanol fuel cell (DMFC), the LDG-supported Pd catalyst has very large electrochemically active surface area (ECSA) values, more than twice as large as that for the reduced graphene oxide, or five times the commercial XC-72 carbon. The forward peak current measurements show similar results. The excellent catalytic performance of LDG/Pd can be attributed to the preserved pristine graphene structure, which not only provides a lot of surface area for the deposition of nanoparticles, but also allows for electrical conductivity and stability in the composite.
164 citations
TL;DR: In this paper, an ionic conductive Nafion/graphene oxide (GO) composite membrane for application in direct methanol fuel cells is presented. But, the authors do not consider the use of GO nanofillers.
151 citations
TL;DR: In this paper, two types of highly ordered mesoporous carbon CMK-8 (I and II) with high surface area and 3-D bicontinuous interpenetrating channels were synthesized and deposited with Pt-Ru nanoparticles using the sodium borohydride reduction method.
Abstract: The cost of the catalysts used in the direct methanol fuel cell poses a challenge to its widespread use as an energy efficient and environment friendly fuel conversion technology. In this study, two types of highly ordered mesoporous carbon CMK-8 (I and II) with high surface area and 3-D bicontinuous interpenetrating channels were synthesized and deposited with Pt–Ru nanoparticles using the sodium borohydride reduction method. The electrocatalytic capabilities for methanol oxidation were investigated using cyclic voltammetry and chronoamperometry, and the results were compared with that of Pt–Ru deposited on Vulcan XC-72 using the same preparation method as well as with commercial Pt–Ru/C (E-TEK) catalyst. Pt–Ru/CMK-8-I synthesized by the method developed in this work revealed an outstanding specific mass activity (487.9 mA/mg) and superior stability compared with the other supports, thus substantiating its potential to reduce the costs of DMFC catalysts.
118 citations
TL;DR: In this article, the glass transition temperature (Tg) of the Nafion 117 membrane was traced by DSC step by step during the preparation of the membrane electrode assembly (MEA).
110 citations
TL;DR: In this article, a direct methanol fuel cell (DMFC) electrode catalysts with improved electrochemical properties have been prepared by dispersing platinum-tin (Pt-Sn) nanoparticles onto graphene sheets.
110 citations
TL;DR: In this paper, a facile and effective route for the synthesis of structurally uniform and electrochemically active nitrogen-doped hollow carbon spheres (NHCSs) via pyrolysis of hollow poly(o-phenylenediamine) (PoPD) spheres was described.
Abstract: This study described a facile and effective route for the synthesis of structurally uniform and electrochemically active nitrogen-doped hollow carbon spheres (NHCSs) via pyrolysis of hollow poly(o-phenylenediamine) (PoPD) spheres. The characters and the mechanism of the transformation between the as-prepared PoPD and the NHCSs were studied. Results showed that the ladder aromatic structure of the as-prepared PoPD was transformed into a polycyclic-type structure in which nitrogen atoms were successfully incorporated into the graphitic structures to replace the carbon atoms. The as-prepared NHCSs showed a much higher electrocatalytic current than multi-wall carbon nanotubes and nitrogen-doped carbon nanotubes for the oxygen reduction reaction through a four-electron pathway in alkaline solution. The enhanced catalytic activity of NHCSs for ORR arose from the doping of nitrogen in the form of quaternary nitrogen, along with pyridinic N and pyrrolic N. The NHCSs also presented high methanol tolerance and long-term operational stability. The results showed that the NHCSs had a promising application in direct methanol fuel cells and provided a new method to synthesize carbon-based metal-free electrocatalysts from organic polymers.
109 citations
TL;DR: In this paper, a summary of acid-base blend membranes consisting of an acidic polymer and a basic compound containing N-heterocycle groups for low temperature fuel cells is presented.
Abstract: Fuel cells hold great promise for wide applications in portable, residential, and large-scale power supplies. For low temperature fuel cells, such as the proton exchange membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs), proton-exchange membranes (PEMs) are a key component determining the fuel cells performance. PEMs with high proton conductivity under anhydrous conditions can allow PEMFCs to be operated above 100 °C, enabling use of hydrogen fuels with high-CO contents and improving the electrocatalytic activity. PEMs with high proton conductivity and low methanol crossover are critical for lowering catalyst loadings at the cathode and improving the performance and long-term stability of DMFCs. This review provides a summary of a number of novel acid-base blend membranes consisting of an acidic polymer and a basic compound containing N-heterocycle groups, which are promising for PEMFCs and DMFCs.
97 citations
TL;DR: In this paper, the quaternized polyvinyl alcohol/3-(trimethyl ammonium) propyl-functionalized silica (QPVA/Q-SiO 2 ) composite polymer membrane is prepared by a solution casting method.
87 citations
TL;DR: In this paper, the authors assess the technological advances that have been made and the impediments that are faced in this development and the critical assessment exercise, it is presumed, may contribute toward a speedy development of this critical component for a viable fuel cell based energy economy.
85 citations
TL;DR: The design and synthesis of small-sized and contacting Pt-WC nanostructures on graphene that bring the synergistic effect into full play and confirm that highly disperse WC nanoparticles can indeed be anchored on graphene.
Abstract: The synergistic effect between Pt and WC is beneficial for methanol electro-oxidation, and makes PtWC catalyst a promising anode candidate for the direct methanol fuel cell. This paper reports on the design and synthesis of small-sized and contacting PtWC nanostructures on graphene that bring the synergistic effect into full play. Firstly, DFT calculations show the existence of a strong covalent interaction between WC and graphene, which suggests great potential for anchoring WC on graphene with formation of small-sized, well-dispersed WC particles. The calculations also reveal that, when Pt attaches to the pre-existing WC/graphene hybrid, Pt particles preferentially grow on WC rather than graphene. Our experiments confirmed that highly disperse WC nanoparticles (ca. 5 nm) can indeed be anchored on graphene. Also, Pt particles 23 nm in size are well dispersed on WC/graphene hybrid and preferentially grow on WC grains, forming contacting PtWC nanostructures. These results are consistent with the theoretical findings. X-ray absorption fine structure spectroscopy further confirms the intimate contact between Pt and WC, and demonstrates that the presence of WC can facilitate the crystallinity of Pt particles. This new PtWC/graphene catalyst exhibits a high catalytic efficiency toward methanol oxidation, with a mass activity 1.98 and 4.52 times those of commercial PtRu/C and Pt/C catalysts, respectively.
TL;DR: In this paper, the electrocatalytic activity and stability of ionic-liquid-assisted nanocomposites for methanol oxidization were investigated using an ionic liquid/water solution, followed by the deposition of nanoparticles on graphene and their further reduction of chloroplatinic acid.
TL;DR: In this paper, the chemical stability and durability of PtRu catalysts supported on carbon nanofibers (CNFs) for the anode electrode of a direct methanol fuel cell (DMFC) are investigated by Pt and Ru dissolution tests in sulfuric acid and long-term performance tests of a single cell discharging at a constant current density of 150 milliamm−2 for approximately 2000h.
TL;DR: PtRu catalysts with similar particle size and composition were deposited on three different carbon supports: Vulcan, graphitized carbon nanofibers (GNF) and few-walled carbon nanotubes (FWCNT) and their performance for methanol oxidation was studied in an electrochemical cell and in a single cell DMFC as mentioned in this paper.
TL;DR: Inspired by the proton conducting mechanism in organisms where the amino acid groups play a crucial and multiple role, a novel kind of amino acid-functionalized titania submicrospheres was prepared and incorporated into sulfonated poly(ether ether ketone) (SPEEK) to fabricate the hybrid membranes for potential application in direct methanol fuel cells as discussed by the authors.
TL;DR: In this paper, a P-MCNT was synthesized by thermolysis and employed as supports to prepare Pt/PMCNTs catalyst for direct methanol fuel cells (DMFCs).
TL;DR: In this paper, poly(diallyldimethylammonium chloride) (PDDA)-functionalized graphene nanosheets (GNSs) were employed for direct methanol fuel cell applications.
TL;DR: In this paper, the catalytic performance of ordered mesoporous carbon (OMC) supported well-dispersed PtFex nanoparticles with a controllable size distribution were investigated using cyclic voltammetry and electrochemical impedance spectroscopy (EIS) technique.
Abstract: Ordered mesoporous carbon (OMC) supported well-dispersed PtFex nanoparticles with a controllable size distribution were prepared via a modified polyol synthesis route, using hexachloroplatinic acid and ferric chloride as Pt and Fe source, and ethylene glycol as a reducing agent. The catalytic activities relevant to direct methanol fuel cell of the PtFex/OMC composites were investigated using cyclic voltammetry, single-cell proton exchange membrane fuel cell (PEMFC) test and electrochemical impedance spectroscopy (EIS) technique. Due to the existence of more Pt0 species and Fe ion corrosion caused by the formation of the alloyed PtFex catalyst, Pt0 can provide the more active sites for methanol oxidation reaction, and the methanol oxidation activity of the PtFex/OMC electrode is evidenced to be enhanced by the increased anodic peak current with increasing the incorporation content of Fe. The oxygen reduction reaction (ORR) current density of 0.662 A cm−2 and power density of 237.2 mW cm−2 generated by the PtFe3/OMC sample are more than two times the values of 0.32 mA cm−2 and 102.6 mW cm−2 by the Pt/OMC sample. The PtFe3/OMC catalyst in 0.5 M H2SO4 + 1 M CH3OH displays the highest specific catalytic activity of 100.6 mA m−2, which is almost 3 times lower than that of 283.7 mA m−2 in 0.5 M H2SO4. The enhanced higher activity for the PtFe3/OMC sample can be firstly attributed to a highly homogeneous dispersion of the PtFe3 nanoparticles on the mesoporous channels within OMC, such PtFe3 nanoparticles with a diameter of 3.3 nm can accelerate the formation of Pt–OH groups. Meanwhile, the alloyed PtFe3 nanoparticles can provide a lower onset potential for the electrooxidation of CO/H2 than that of pure Pt, and would contribute more to the promotion of C–H breaking and COad tolerance. Furthermore, the larger surface area, the favorable pore structure and the structural integrity between the PtFe3 nanoparticles and the OMC matrix, will effectively facilitate the transportation of reactants and products in liquid electrochemical reactions.
TL;DR: The results obtained demonstrate that diamond supported catalyst nanomaterials are promising for methanol fuel cells.
Abstract: Diamond in nanoparticle form is a promising material that can be used as a robust and chemically stable catalyst support in fuel cells. It has been studied and characterized physically and electrochemically, in its thin film and powder forms, as reported in the literature. In the present work, the electrochemical properties of undoped and boron-doped diamond nanoparticle electrodes, fabricated using the ink-paste method, were investigated. Methanol oxidation experiments were carried out in both half-cell and full fuel cell modes. Platinum and ruthenium nanoparticles were chemically deposited on undoped and boron doped diamond nanoparticles through the use of NaBH(4) as reducing agent and sodium dodecyl benzene sulfonate (SDBS) as a surfactant. Before and after the reduction process, samples were characterized by electron microscopy and spectroscopic techniques. The ink-paste method was also used to prepare the membrane electrode assembly with Pt and Pt-Ru modified undoped and boron-doped diamond nanoparticle catalytic systems, to perform the electrochemical experiments in a direct methanol fuel cell system. The results obtained demonstrate that diamond supported catalyst nanomaterials are promising for methanol fuel cells.
TL;DR: In this article, a novel PtPd/C catalyst with hollow spherical structure has been successfully prepared by electrostatic self-assembly one-step reductive route using sodium dodecyl sulfate as a capping and structure-directing agent in ethylene glycol solution by microwave assisted process.
TL;DR: In this article, the performance of derivative voltammetry in the analysis of methanol oxidation reaction (MOR) with regard to direct methanoline fuel cell has been delineated.
Abstract: Application of derivative voltammetry to methanol oxidation reaction (MOR) has been studied, and its advantage in the analysis of various aspects of MOR with regard to direct methanol fuel cell has been delineated. The derivative technique of voltammetric analysis was employed in evaluating and comparing MOR activities of carbon-supported mono-, bi-, and tri-metallic electrocatalysts. Significant enhancement in the accuracy of estimating voltammetric peak potential and onset potential of methanol oxidation current can be achieved in derivative voltammetry. Furthermore, the better signal-to-noise ratio of derivative voltammetry practically eliminates charging current. From a mechanistic point of view, derivative voltammetry is highly sensitive in resolving a peak due to parallel path mechanism. Electrochemical stability of anode catalysts can be better evaluated and monitored employing derivative voltammetry. Nevertheless, the derivative technique is simple and does not require further instrumentation or c...
TL;DR: This work reports a DBFC in which a polymer fiber membrane was used, and metal oxides were used as cathode catalysts, meanwhile CoO was used as anode catalyst, and peak power density has been achieved at 65°C, which increases by a factor of 1.7 compared with classic DBFCs.
Abstract: Polymer electrolyte membranes (PEM) and Pt-based catalysts are two crucial components which determine the properties and price of fuel cells. Even though, PEM faces problem of fuel crossover in liquid fuel cells such as direct methanol fuel cell (DMFC) and direct borohydride fuel cell (DBFC), which lowers power output greatly. Here, we report a DBFC in which a polymer fiber membrane (PFM) was used and metal oxides, such as LaNiO3 and MnO2, were used as cathode catalysts, meanwhile CoO was used as anode catalyst. Peak power density of 663 mW·cm−2 has been achieved at 65°C, which increases by a factor of 1.7–3.7 compared with classic DBFCs. This fuel cell structure can also be extended to other liquid fuel cells, such as DMFC.
TL;DR: In this paper, a series of poly(ether ether ketone) copolymers containing methyl groups on the side chain were prepared based on a new monomer (3,4-dimethyl)phenylhydroquinone.
Abstract: A series of novel poly(ether ether ketone) copolymers containing methyl groups on the side chain were prepared based on a new monomer (3,4-dimethyl)phenylhydroquinone. Then a series of hydroxide exchange membranes with different IEC values were obtained through bromination and quaternary amination of the copolymers. By adjusting the contents of methyl groups in the copolymers, we could control the final structures of the membranes. The chemical structures of the monomers and copolymers were analyzed by 1H NMR spectroscopy. After that, for the purpose of enhancing the dimensional stability and methanol resistance of the membrane, we prepared cross-linked membranes through a Friedel–Crafts reaction between bromomethyl groups and aromatic rings. The properties of the membranes related to fuel cell application were evaluated in detail. All the membranes showed good thermal and mechanical stabilities and conductivities. Moreover, the cross-linked membranes exhibit better dimensional stabilities and selectivities. Among those membranes, xPEEK–Q-100 showed a high conductivity (0.036 S cm−1 at 80 °C), a low swelling ratio of 6.6% and a methanol permeation coefficient of 2.9 × 10−7 cm2 s−1. The outstanding properties indicated that the application of PEEK–Q-xx membranes in fuel cells was promising.
TL;DR: In this article, the platinum nanoclusters attached graphene composite (PtNCs/graphene) was characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), TEM, and energy dispersive Xray spectroscopy (EDS).
TL;DR: Sulfonated SiO2 nanoparticles with uniform core-shell structure are synthesized and used as functional fillers for preparing composite proton conducting membranes for direct methanol fuel cells (DMFCs) as mentioned in this paper.
TL;DR: In this paper, a series of Nafion composite membranes with improved methanol barrier properties were fabricated from chitosan (CS) and silicotungstic acid (SiWA) by Layer-by-layer self-assembly technique.
TL;DR: In this article, the effect of various reducing methods on the influence of particle size vis-a-vis on the electrocatalytic effect is investigated, and the results of the synthetic methods, characterization techniques and the performance indicate that the Pt/CMK-3 catalysts are superior to that prepared with activated carbon (Pt/AC) as well as with that of the commercial platinum-supported carbon catalyst (Pit/E-TEK).
TL;DR: In this paper, a triple-layer proton exchange membrane comprising two thin layers of structurally modified chitosan, as methanol barrier layers, both sides coated with Nafion®105 is prepared and tested for high-performance direct methanoline fuel cell applications.
TL;DR: In this paper, a new class of carbon materials which are produced via selective extraction of the non-carbon compounds from metal carbides was produced in consequence of chlorinating pure titanium carbide, which was oxidatively treated to create the nucleation sites for the metal precursor.
TL;DR: In this paper, the effect of the zeolite loading on the mobility of both liquid and vapor water through the Nafion membrane has been investigated by using two complementary techniques, that is, differential scanning calorimetry and dynamic vapor sorption.
Abstract: Nafion/Faujasite zeolite composite membranes have been prepared by solution casting at a zeolite content ranging from 0.98 to 21.4 wt %. The effect of the zeolite loading on the mobility of both liquid and vapor water through the Nafion membrane has been investigated by using two complementary techniques, that is, differential scanning calorimetry and dynamic vapor sorption. The relationship between water mobility, proton conductivity, and direct methanol fuel cell (DMFC) performance of composites is also discussed. The addition of zeolite contributes to the enhancement of the water mobility degree in the composite membrane due to both the surface composition of the additive and the introduction of porosity at the polymer/filler interface. Nafion/zeolite composites having higher proton conductivity and DMFC performance than bare Nafion can thus be fabricated by fine-tuning of the additive content and the membrane morphology.