Direct Methanol Fuel Cell Applications Research Articles

Enhanced Cell Performance and Improved Catalyst Utilization for a Direct Methanol Fuel Cell with an In-Plane Gradient Loading Catalyst Electrode

Direct methanol fuel cells (DMFCs) offer high energy density, simple liquid fuel storage, and the ability to operate at ambient temperature. They may be used in a variety of portable mobile power supplies, small civilian power supplies, and automotive power supplies. However, in the process of electrochemical reaction inside a DMFC, because the reactants and products are distributed unevenly, the in-plane concentration of reactants and reaction rate are different; thus, the current density generated in the active area shows a high degree of non-uniformity. The high local current density can easily lead to the acceleration of DMFC aging. As a result, the operating cost of the DMFC is increased and the service life is shortened, which limits the commercial application of DMFCs. In this work, we develop an in-plane gradient loading catalyst. The loading on both the anode and cathode catalysts was lower near the inlet and higher close to the outlet. The experimental results of the single-cell test show that the performance of the gradient loading catalyst electrode was enhanced by up to 19.8% compared with the uniform loading catalyst at 60 °C for the same catalyst loading, especially under high current densities. In addition, the catalyst utilization was improved for the gradient loading catalyst electrode. Hence, the proposed approach shows potential for reducing the cost and increasing the service life of DMFCs.

A promising star-like PtNi and coral reefs-like PtCo nano-structured materials for direct methanol fuel cell application

Novel composite catalysts of nanostructured PtCo and PtNi alloys onto a coated glassy carbon electrode (GCE) with a nanostructured alloy of NiCo as a substrate material were fabricated by an electrodeposition method from their salt solutions at ambient temperature. The PtCo/NiCo/GCE and the PtNi/NiCo/GCE catalysts display an improved electrocatalytic behavior for the electrochemical oxidation reaction of methanol (MOR). The morphology, chemical composition, and phase structure for the electrodeposited catalysts were checked utilizing a scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDAX), and X-ray diffraction (XRD) technique, respectively. PtCo/NiCo/GCE catalyst shows coral particles of reef-shaped morphology, whilst the PtNi/NiCo/GCE catalyst star-shaped particles. The electrocatalytic performance of the electrodeposited catalysts was verified using chronoamperometry and cyclic voltammetry (CV). The effects of the type of electrodeposition method, pH of the solution, temperature, and precursors concentration on the characteristics of the PtCo and PtNi alloys electrodeposits and accordingly on the electrocatalytic peculiarities of the catalysts were well assessed. Furthermore, the impact of methanol concentration and temperature on MOR was discussed. The stability and the corrosion resistance tests of the PtNi/Ni-Co/GCE and PtCo/Ni-Co/GCE systems were evaluated via the electrochemical impedance spectroscopy (EIS), Tafel polarization, and potentiostatic methods.

Synthesis of Composite Membrane Based Biopolymer Chitosan With Silica From Rice Husk Ash For Direct Methanol Fuel Cell Application

A membrane chitosan with silica from rice husk ash was fabricated as alternative membrane electrolyte for direct methanol fuel cell (DMFC) application. Chitosan is made from shrimp shell powder which is processed through deproteination, demineralization and deacetylation steps. Furthermore, the phase diversion technique was used to synthesis membranes by mixing chitosan and silica in acetic acid solution. The resultant membrane characterized with FTIR, water and methanol uptake, ion exchange capacity, and methanol permeability. FTIR analysis showed that chitosan and silica was successfully synthesized. Water uptake for the chitosan-silica membrane increased with increasing silica loading, but the methanol uptake value decreased. The chitosan-silica with 15 wt% silica loading exhibited the best ion exchange capacity and methanol permeability which were 1.290 meq/gram and 2.42 x 10−4 cm2/s, respectively. All the result obtained from this studi shown that chitosan-silica membrane is a promising electrolyte membrane for direct methanol fuel cell application.

Polyaniline decorated graphene oxide on sulfonated poly(ether ether ketone) membrane for direct methanol fuel cells application

AbstractIn direct methanol fuel cells (DMFC), methanol crossover is a major issue which has reduced the performance of polymer electrolyte membrane (PEM) for energy generation. In this study, graphene oxide (GO) and conductive polyaniline decorated GO (PANI‐GO) were used as additives in fabrication of sulfonated poly(ether ether ketone) (SPEEK) nanocomposite PEM membrane to reduce methanol crossover. PANI‐GO was synthesized by in situ polymerization method and the formation of PANI coated GO nanostructures was confirmed by surface morphology and crystallinity analysis. The membrane morphology and topography analysis confirmed that GO and PANI‐GO were well dispersed on the surface of SPEEK membrane. 0.1 wt% PANI‐GO modified SPEEK nanocomposite membrane exhibited the highest water uptake and ion exchange capacity of 40% and 1.74 meq g−1, respectively. The oxidative stability of the nanocomposite membranes also improved. Lower methanol permeability of 4.33 × 10−7 cm−2S−1 was noticed for 0.1 wt% PANI‐GO modified SPEEK membrane. PANI‐GO modified SPEEK membrane enhanced the proton conductivity, which was due to the existence of acidic and hydrophilic group present in PANI and GO. PANI‐GO modified SPEEK membrane held higher selectivity of 1.94 × 104 S cm−3 s−1. Overall, these studies revealed that PANI‐GO modified SPEEK membrane is a potential material for DMFC applications.

Improved methanol electrooxidation catalyzed by ordered mesoporous Pt-Ru-Ir alloy nanostructures with trace Ir content

Mesoporous nanostructures of Pt alloy with Ru-Ir as trimetallic electrocatalyst exhibits significant performance for direct methanol fuel cell (DMFC). In this study, the ordered mesoporous nanostructure (OMNs) of Pt-Ru-Ir catalyst was prepared through the KIT-6 mesoporous silica template-assisted chemical reduction method. The OMN of Pt-Ru-Ir possesses high Pt utilization and a low Ir content, resulting in promoted MOR kinetics by the bi-functional mechanism of its oxophilic nature. In addition, the oxides of both Ru and Ir further enhanced the electrocatalytic efficiency of Pt by producing more active sites owing to its ordered mesoporous morphology and bifunctional mechanism. Furthermore, the OMNs of Pt0.7Ru0.25Ir0.05 electrocatalyst has a substantial electrochemical surface area (ECSA) of 78.35 m2 g−1 with 1721 mA mg−1 of mass activity, which is comparatively 2-3 times higher than all other catalysts reported here. Notably, the ECSA loss (19.5 %) after 5000 durability cycles was found much lesser than other compositions, Pt/C and Pt0.7Ru0.3 catalyst owing to the synergistic effect between Pt and Ru with a trace amount of Ir, smaller particle size, and unique ordered mesoporous morphology. Another significant factor is the rate of CO poisoning during MOR, which was found to be much lesser than others for the Pt0.7Ru0.25Ir0.05 catalyst (∼0.0047 %) studied by chronoamperometry test. The results indicate that the unique OMNs of Pt-Ru-Ir is an excellent MOR catalyst for DMFC applications.

Carbon monoxide-resistant copper-cobalt nanocrystal@ nitrogen-doped carbon electrocatalysts for methanol oxidation reaction

The performance of direct methanol fuel cells (DMFC) mainly depends on the activity and stability of the noble-metal-based anode catalysts for methanol oxidation reaction (MOR), whose broad application is limited by the scarcity of noble metals and their susceptibility to carbon monoxide poisoning. Many efforts have been devoted to the developing of non-noble metal based MOR catalysts. Previous studies have shown that the catalytic properties of noble-metal catalysts can be modified by alloying in nanomaterials. However, non-noble metal-based nanocrystals are rarely studied as electrocatalysts, because of their high susceptibility to air oxidation. Herein, we report a simple strategy to prepare non-noble metal nanocrystals (Cu-Co nanocrystals), which are stabilized in a nitrogen-doped carbon (N-C) matrix to form Cu-Co@N-C composite. Since Co has a high activity for oxidation reactions, and Cu has a high adsorption capacity for methanol, the Cu-Co nanocrystals should present good MOR activity because of the synergistic effect of Cu and Co. The highly active Cu-Co nanocrystals are embedded in a porous N-C matrix with a large specific surface area (127.3 m2/g), which not only protects the Cu-Co nanocrystals, but also facilitate the mass and charge transfer. Indeed, the optimal Cu-Co@N-C catalyst shows a MOR activity of 171.3 mA/cm2 at 0.6 V vs SCE in alkaline medium, which is higher than most of previously reported Cu and Co-based MOR catalysts. The stability and CO-resistance of the optimal Cu-Co@N-C catalyst are also better than that of Pt/C catalyst, enabling Cu-Co@N-C a promising MOR catalyst for broad application of DMFC.

Highly Conductive Polyelectrolyte Membranes Poly(vinyl alcohol)/Poly(2-acrylamido-2-methyl propane sulfonic acid) (PVA/PAMPS) for Fuel Cell Application.

In this study, chemically cross-linked PVA/PAMPS membranes have been prepared to be used in direct methanol fuel cells (DMFCs). The structural properties of the resultant membrane were characterized by use FTIR and SEM. Additionally, their thermal stability was assessed using TGA. Moreover, the mechanical properties and methanol and water uptake of membrane was studied. The obtained FTIR of PVA/PAMPS membranes revealed a noticeable increase in the intensity of adsorption peaks appearing at 1062 and 1220 cm−1, which correspond to sulfonic groups with the increasing proportion of PAMPS. The thermograms of these polyelectrolyte membranes showed that their thermal stability was lower than that of PVA membrane, and total weight loss gradually decreased with increasing the PAMPS. Additionally, the functional properties and efficiency of these polyelectrolyte membranes were significantly improved with increasing PAMPS proportion in these blends. The IEC of polymer blend membrane prepared using PVA/PAMPS ratio of 1:1 was 2.64 meq/g. The same membrane recorded also a methanol permeability coefficient of 2.5 × 10−8 cm2/s and thus, its efficiency factor was 4 × 105 greater than that previously reported for the commercial polyelectrolyte membrane, Nafion® (2.6 × 105). No significant increase in this efficiency factor was observed with a further amount of PAMPS. These results proved that the PVA:PAMPS ratio of 1:1 represents the optimum mass ratio to develop the cost-effective and efficient PVA/PAMPS blend membranes for DMFCs applications.

Organic-Inorganic Novel Green Cation Exchange Membranes for Direct Methanol Fuel Cells

Commercializing direct methanol fuel cells (DMFC) demands cost-effective cation exchange membranes. Herein, a polymeric blend is prepared from low-cost and eco-friendly polymers (i.e., iota carrageenan (IC) and polyvinyl alcohol (PVA)). Zirconium phosphate (ZrPO4) was prepared from the impregnation–calcination method and characterized by energy dispersive X-ray analysis (EDX map), X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM), then incorporated as a bonding and doping agent into the polymer blend with different concentrations. The new fabricated membranes were characterized by SEM, FTIR, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and XRD. The results revealed that the membranes’ physicochemical properties (oxidative stability, tensile strength) are enhanced with increasing doping addition, and they realized higher results than Nafion 117 because of increasing numbers of hydrogen bonds fabricated between the polymers and zirconium phosphate. Additionally, the methanol permeability was decreased in the membranes with increasing zirconium phosphate content. The optimum membrane with IC/SPVA/ZrPO4-7.5 provided higher selectivity than Nafion 117. Therefore, it can be an effective cation exchange membrane for DMFCs applications.

Highly Stable NiCoZn Ternary Mixed-Metal-Oxide Nanorods as a Low-Cost, Non-Noble Electrocatalyst for Methanol Electro-Oxidation in Alkaline Medium

There is an imperative necessity to develop low-cost and efficient nanocatalysts as a substitute for expensive and rare noble-metal catalysts such as platinum (Pt) and gold (Au) in overcoming the limitations of carbon monoxide and intermediate poisoning in direct methanol fuel cells (DMFCs). Herein, we report a simple, one-step hydrothermal synthesis of NiCoZn ternary mixed-metal-oxide nanorod (NCZMMO)-modified glassy carbon electrode (NCZMMO/GCE) for DMFC application. The NCZMMO/GCE electrode exhibits outstanding electro-oxidation of methanol (MeOH) at a low onset potential of 0.30 V (vs Ag|AgCl) with a high current density of 414 mA/mg in an alkaline medium (1 M KOH). This outstanding performance of the electrode is ascribed to the synergistic outcome of NCZMMO nanorods, where Ni imparts the electrocatalytic active sites for methanol oxidation reaction (MOR) through its multiple oxidation states while the excellent mechanical and chemical stability of the electrode is attributed to the oxides of Co and Zn. The electrode exhibits outstanding durability with 75% retention even at 5000 s of chronoamperometry analysis in the presence of 0.5 M MeOH, which is far superior to other reported noble-metal electrocatalysts. This superior performance of NCZMMO frontlines it as a promising non-noble, low-cost electrocatalyst for various energy conversion applications.

Preparation and Properties of Chitosan/Montmorillonite Supported Phosphotungstic Acid Composite Membrane for Direct Methanol Fuel Cell Application

Chitosan powder is synthesized by a deasetylation process of chitin, obtained from processing of dried shrimp shell powder. Subsequently, chitosan (CS) membranes filled by montmorillonite (MMT) particles and phosphotungstic acid are prepared, and characterized by FT-IR and SEM. The morphology, obtained by SEM for the composite membrane, showed that MMT filler is successfully incorporated and relatively well dispersed in the chitosan polymer matrix. Water and methanol uptake for the CS/MMT composite membranes decrease with increasing MMT loadings, but IEC value increases. In all prepared CS/ MMT composite membranes, the CS membrane filled by 5 wt% MMT particles exhibits the best proton conductivity, while that with 10 wt% MMT loading exhibits the lowest methanol permeability; these values are 2.67 mS·cm−1 and 3.40 × 10−7 cm2·s−1, respectively. The best membrane selectivity is shown in the CS/MMT10 composite membrane; this shows that 10 wt% filled MMT is the optimum loading to improve the performance of the chitosan composite membrane. These characteristics make the developed chitosan composite membranes a promising electrolyte for direct methanol fuel cell (DMFC) application.

Titanium dioxide nanoparticle incorporated PVDF-HFP based composite membrane for direct methanol fuel cells application

Two composite polymeric membranes were synthesized using poly vinylidene fluoride-hexafluoroprropylene (PVDF-HFP) host in polyvinyl alcohol and with or without TiO2 nanoparticlesas a porous substrate. The structure of the membranes was PDVF-HFP/PVA and PVDF-HFP/PVA/TiO2.The composition of the synthesized membranes was analyzed by FTIR spectrum.The porosity of the polymer membranes were measured by immersing the membranes into n-butanol. The conductivity of the composite membranes was determined by impedance spectroscopy and the methanol permeability of the membranes was obtained from diffusion experiments. The surface morphology images were investigated by scanning electron microscope(SEM). The SEM image of the composite membrane incorporated with TiO2 has many pores which increased the conductivity of the membrane as compared to non TiO2 incorporated one. The composite membrane with TiO2 showed a good balance between proton conductivity and methanol permeability. The cell with PVDF-HFP/PVA/TiO2 composite membrane showed higher power density.
 Bangladesh J. Sci. Ind. Res.56(2), 125-132, 2021

A sensor of liquid methanol for direct methanol fuel cells

The methanol sensors are of significance to maintain the efficient and stable operation of direct methanol fuel cells (DMFCs). The issues, including stability, the relationship between temperature, current density and concentration need, however, urgent attention. A novel electrochemical methanol sensor which is based on current output limited by methanol diffusion is developed. The stability of sensors was lifted steeply through introducing a reference electrode, narrowing the methanol flow channel, and adding a water container. The relationship between the temperature, response current and methanol concentration was determined with the help of theoretical derivation and the validity was verified by the fitting result. Other sensors can avail of this relationship to correct the temperature effect. Application test indicated that the sensor may be of great potential for the accurate monitoring of methanol concentration at the levels of DMFCs application.

Functionalized boron nitride embedded sulfonated poly (ether ether ketone) proton exchange membrane for direct methanol fuel cell applications

Nanostructured materials have been utilized in tailoring the proton exchange membrane (PEM) with the attempt to reduce the methanol transport and enhance proton conductivity in direct methanol fuel cell (DMFC) applications. In this study, polyaniline coated activated boron nitride (PANI-A-BN) was embedded in sulfonated poly (ether ether ketone) (SPEEK) membranes for DMFC applications. The influence of boron nitride (BN) and activated boron nitride (A-BN) was also compared. The crystallinity and morphological analyses revealed that structure of PANI-A-BN nanocomposites were altered. The dispersion of functionalized BN was clearly witnessed from the SEM and AFM images of SPEEK membranes PANI-A-BN/SPEEK membrane exhibited a higher water uptake (58.42%) and ion exchange capacity (IEC) (1.76 meqg−1) compared to other membranes prepared in this work. The methanol permeability was significantly reduced in BN and functionalized BN embedded SPEEK nanocomposites membranes (3.08 ×10−7 cm−2S−1). The proton conductivity and chemical stability of PANI-A-BN/SPEEK membrane were improved. The DMFC performance of nanocomposite membrane was compared with that of commercial Nafion membrane. 0.1 wt% PANI-A-BN/SPEEK membrane exhibited the highest open circuit voltage and power density of 0.158 V and 11.38 mW/cm2, respectively.

Synthesis and characterization of conductive polymer coated graphitic carbon nitride embedded sulfonated poly (ether ether ketone) membranes for direct methanol fuel cell applications

Direct methanol fuel cell (DMFC) is a sustainable energy conversion device that is known for its advantages in terms of portability as well as can be stored and transported safely. Functionalized nanostructured materials have been used in proton exchange membrane (PEM) for DMFC applications to enhance the proton conductivity and suppress the methanol permeability. In this study, conductive polyaniline deposited oxidized graphitic carbon nitride (PANI-O-g-C3N4) was incorporated in sulfonated poly (ether ether ketone) (SPEEK) membrane for DMFC applications. The performances of graphitic carbon nitride (g-C3N4) and oxidized graphitic carbon nitride (O-g-C3N4) on SPEEK PEM were also assessed and compared. The morphological and X-ray diffraction analysis indicated that the structure and crystallinity were altered with the deposition of PANI on g-C3N4. The scanning electron microscopy and topography analysis revealed that the existence of g-C3N4 and functionalized g-C3N4 were clearly seen on the surface of the SPEEK membrane. Water uptake capacity and ion exchange capacity were significantly improved in the functionalized g-C3N4-modified SPEEK membrane (O-g-C3N4/SPEEK and PANI-O-g-C3N4/SPEEK). The lower methanol permeability and higher proton conductivity of 3.71 × 10−7 cm−2 S−1 and 5.34 × 10−3 S cm−1 were recorded by 0.1 wt% PANI-O-g-C3N4 incorporated SPEEK membrane. Functionalized g-C3N4-modified SPEEK membrane also exhibited higher oxidative stability. The performance of the PANI-O-g-C3N4 incorporated SPEEK membrane in DMFC application highlights its potential as a superior nanofiller for the modification of PEM.

Electrosynthesis of hierarchical Cu2O–Cu(OH)2 nanodendrites supported on carbon nanofibers/poly(para-phenylenediamine) nanocomposite as high-efficiency catalysts for methanol electrooxidation

The development of highly efficient catalysts using inexpensive and earth-abundant metals is a crucial factor in a large-scale commercialization of direct methanol fuel cells (DMFCs). In this study, we explored a new catalyst based on copper nanodendrites (CuNDs) supported on carbon nanofibers/poly (para-phenylenediamine) (CNF/PpPD) nanocomposite for methanol oxidation reaction (MOR). The catalyst support was prepared on a carbon paste electrode by electropolymerization of para-phenylenediamine monomer on a drop-cast carbon nanofibers network. Afterwards, CuNDs were electrodeposited on the nanocomposite through a potentiostatic method. The morphology and the structure of the prepared nanomaterials were characterized by transmission electron microscope, scanning electron microscope, energy dispersive X-ray, X-ray diffraction, and X-ray photoelectron spectroscope. The results suggested that a three-dimensional nanodendritic structure consisting of Cu2O and Cu(OH)2 formed on the hybrid CNF/PpPD nanocomposite. The catalytic performance of CuNDs supported on CNF, PpPD and CNF/PpPD was evaluated for MOR under alkaline conditions. The CNF/PpPD/CuNDs exhibits a highest activity (50 mA cm−2) and stability toward MOR over 6 h, with respect to CNF/CuNDs (40 mA cm−2) and PpPD/CuNDs (36 mA cm−2). This inexpensive catalyst with high catalytic activity and stability is a promising anode catalyst for alkaline DMFC applications.

L-tyrosine grafted palladium graphite oxide and sulfonated poly(ether ether ketone) based novel composite membrane for direct methanol fuel cell

This work involves synthesis of amino acid grafted palladium graphite oxide based nanocomposites as proton exchange membranes for direct methanol fuel cell applications (DMFC) and determination of their selectivity. Membrane synthesis includes grafting of L-tyrosine on palladium decorated graphite oxide (Pd-GO-L-Tyr) in a polymeric substrate viz. sulfonated poly(ether ether ketone) (SPEEK) by solution casting. Pd-GO-L-Tyr composites were characterized by FT-IR and XPS to analyze the functional groups and constituent elements to confirm successful functionalization of amino acid. The surface morphology was studied by scanning electron microscopy (SEM), atomic force microscopy (AFM) and transmission electron microscopy (TEM). The physicochemical properties of the SPEEK/Pd-GO-L-Tyr membranes such as ion exchange capacity (IEC), water uptake, methanol permeability and proton conductivity were measured. The results include significant improvement in blocking of methanol upon modification of Pd-GO-L-Tyr. On one hand, presence of Pd and GO inhibits the methanol permeability, while on the other L-Tyr significantly increases the conductivity of the membrane. Both these factors result in higher selectivity of the Pd-GO-L-Tyr-SPEEK composite membrane for DMFC applications, compared to that of benchmark Nafion-117 membrane.

Improvement in properties of nanocrystalline cellulose/poly (vinylidene fluoride) nanocomposite membrane for direct methanol fuel cell application

Improving methanol resistance and dimensional stability are the main challenges in polymer electrolyte membranes for direct methanol fuel cell application. In this study, nanocrystalline cellulose (NCC) was initially synthesized and then blended together with poly (vinylidene fluoride) (NCC/PVDF) and the resultant dope solution was used for the fabrication of membranes via solution casting method. The physical characteristics of the membranes were evaluated using scanning electron microscopy (SEM) and Fourier transform infrared (FTIR). Crystallinity differences between all the membranes were confirmed by x-ray diffraction (XRD). Results revealed that the swelling ratio at 80° C and methanol permeability of NCC-3/PVDF were as low as 15.19% and 2.69 × 10−9 cm2/s, respectively compared to Nafion 117 (18.25% and 2.74 ×10−6 cm2/s). It was found that blending hydrophilic NCC with hydrophobic PVDF could profoundly influence the physical properties of the membrane. High crystallinity structure of NCC/PVDF membrane significantly improved the dimensional stability and reduce methanol permeation rate. Although the proton conductivity of NCC-3/PVDF (7.57 ×10−2 mS cm−1) is low, its selectivity (28.141 ×103 Scm−3s) was higher than that of Nafion 117 (0.074 ×103 Scm−3s) due to improvements in methanol barrier. The alternative membrane prepared from NCC and PVDF successfully overcame the weaknesses of Nafion 117, hence exhibiting its potential for DMFC application.

An overview of synthetic polymer-based membrane modified with chitosan for direct methanol fuel cell application

The materials used for fuel cell membrane must have a high proton conductivity, a strong enough wall to block the reactant flow rate and be chemically or mechanically stable in the environment around the fuel cell. To improve the effectiveness of fuel cell membranes and reduce production costs, several synthetic polymer membranes have been developed, including polyethersulfone, polysulfone, polyvinyl alcohol, and polystyrene. Membranes from this polymer have the advantage of being cheap, commercially available, and allowing its structure to store moisture so it can operate at higher temperatures, yet it has low hydrophilic property. Chitosan, as a biopolymer that has strong hydrophilicity property resulted from numerous hydrophilic groups (e.g. –OH, –NH2 and –NR3 þ), can be used for various chemical modifications including to increase mechanical and chemical stability and modification to the possibility of producing ion exchange and increasing ionic conductivity which is a requirement for fuel cell membrane. The purpose of this study is to review the use of chitosan as synthetic polymer-based membrane modification from its structure and properties. Recent achievements and prospect of its applications have also been included.

Synthesis of Highly Active Pd@Cu-Pt/C Methanol Oxidation Electrocatalysts via Continuous, Co-Electroless Deposition.

Controlled deposition of metals is essential for the creation of bimetallic catalysts having predictable composition and character. Continuous co-electroless deposition (co-ED) permits the creation of bimetallic catalysts with predictive control over composition. This method was applied to create a suite of Cu–Pt mixed-metal shell catalysts for use in methanol electrooxidation in direct methanol fuel cell applications (DMFCs). Enhanced performance of Cu–Pt compositions over Pt alone was predicted by existing computational studies in the literature. Experimental evidence from this study supports the bifunctional catalyst explanation for enhanced activity and confirms the optimum Cu:Pt ratio as Cu3Pt for this methanol electrooxidation. This ability to control the composition of a bimetallic shell can be extended to other systems where the ratio of two metals is critical for catalytic performance.

The synergistic effect of polyorganosilicon and sulfonic groups functionalized graphene oxide on the performance of sulfonated poly (ether ether ketone ketone) polyelectrolyte material

It is a challenge to simultaneously improve proton conductivity, methanol resistance and physicochemical stability of polymer electrolyte membranes (PEMs) used in direct methanol fuel cell (DMFC). In response to this situation, the crosslinked nanocomposite membranes are prepared by introducing polyorganosilicon with various functional groups and sulfonic groups functionalized graphene oxide (SFGO) to the sulfonated poly (ether ether ketone ketone) in this paper. Based on our knowledge, no such PEM materials have been designed and prepared by this method. Scanning electron microcopy images demonstrate that there are good compatibility and connectivity between the matrix and fillers. The combination of polyorganosilicon and SFGO significantly improves the comprehensive performance of membrane, including mechanical property, dimensional stability, proton conductivity, methanol resistance, selectivity, oxidative and hydrolytic stabilities, cell performance, etc. Especially, the nanocomposite membrane with 3 wt% SFGO shows the highest conductivity (0.074 S cm−1 at 25 °C) and lowest methanol diffusion coefficient (3.56 × 10−7 cm2 S−1), which result in the optimal selectivity (2.08 × 105 Ss cm−3). In addition, the maximum power density (73.76 mW cm−2) of the membrane with 3wt% SFGO is higher than that of commercial Nafion@ 117 (61.59 mW cm−2) under identical experimental conditions. These results indicate that the crosslinked nanocomposite membranes will be new alternative to substitute the expensive Nafion® 117 for DMFC application.