Fabrication Of Proton Exchange Membranes Research Articles

Dimethylamine-tuned guanidinium arylphosphonate iHOFs and superprotonic conduction Nafion hybrid membranes for DMFCs

The fabrication of proton exchange membranes (PEMs) with excellent conductivity and low methanol permeability is critical but challenging for the further development of high-performance direct methanol fuel cells (DMFCs). In this work, two ionic hydrogen-bonded organic frameworks (iHOF-14 and iHOF-15) are obtained from 1,3,5-tris(4-phosphonophenyl)benzene and guanidine hydrochloride under the control of dimethylamine cations. Due to the abundant hydrogen bonding network, iHOF-14 and iHOF-15 exhibit good proton conductivity of over 10–2 S cm−1. In addition, we dope the iHOFs into Nafion matrix to get the PEMs with richer proton transport pathways and good methanol barrier properties. At 100 °C and 98 % RH, the conductivity of 9 %-iHOF-14/Nafion and 9 %-iHOF-15/Nafion reaches up to 1.53 × 10–1 and 1.78 × 10–1 S cm−1, respectively. The 72 h permeation experiment results show that the methanol permeability of the composite membranes is 73.7 % lower than that of the recast Nafion. The maximum power densities of hybrid membranes for DMFCs reach about 80 mW cm−2, which is 1.5 times higher compared to the recast Nafion. This work not only enriches the high proton conductivity of arylphosphonate iHOFs, but also expands iHOFs/Nafion PEMs materials for DMFCs.

Supramolecular complexation of metal oxide clusters in PVDF-PVP blends for large scale fabrication of proton exchange membranes for fuel cells

The perfluorosulfonic acid (PFSA) polymers have achieved great success as proton exchange membranes (PEMs) in various energy storage and conversion devices; nevertheless, the improvements regarding PEMs' synthetic cost, mechanical properties, stability and processability are still urgently required. Herein, 1 nm super acidic metal oxide cluster, H3PW12O40 (PW12), is complexed with the blends of polyvinylpyrrolidone (PVP) and polyvinylidene fluoride (PVDF) to afford nanocomposite PEMs that enables the stable and effective operation of hydrogen fuel cell devices. As the polymer matrix, the PVDF is blended with PVP via inter-chain hydrogen bonding to provide mechanical support for the nanocomposite PEMs. The further introduced PW12 clusters can interact strongly with PVP via electrostatic attraction to enhance the PEMs' mechanical strength (E = 231 MPa) and prevent the leaching of PW12 for long-term stability. Meanwhile, the incorporation of the super acidic PW12 can facilitate the fast proton transportation and therefore, lead to the significant increasement of proton conductivity to 9.8 × 10−3 S cm−1 at 70 °C and 100% RH. Due to the excellent mechanical properties and the supramolecular interaction among the components, the PEMs’ thickness can be controlled to be challenging ∼10μm for feasible large-scale continuous processing. Finally, the molecular design enables the successful fabrication of the nanocomposite PEMs into fuel cell devices with the power density as 342.8 mW cm−2. The studies not only shed light on the structure-properties of polymer nanocomposites, but also pave avenues to the design of robust composite PEMs for fuel cell appliacations.

Supramolecular Complexation of Metal Oxide Cluster and Non‐Fluorinated Polymer for Large‐Scale Fabrication of Proton Exchange Membranes for High‐Power‐Density Fuel Cells

AbstractCost‐effective, non‐fluorinated polymer proton exchange membranes (PEMs) are highly desirable in emerging hydrogen fuel cells (FCs) technology; however, their low proton conductivities and poor chemical and dimension stabilities hinder their further development as alternatives to commercial Nafion®. Here, we report the inorganic‐organic hybridization strategy by facilely complexing commercial polymers, polyvinyl butyral (PVB), with inorganic molecular nanoparticles, H3PW12O40 (PW) via supramolecular interaction. The strong affinity among them endows the obtained nanocomposites amphiphilicity and further lead to phase separation for bi‐continuous structures with both inter‐connected proton transportation channels and robust polymer scaffold, enabling high proton conductivities, mechanical/dimension stability and barrier performance, and the H2/O2 FCs equipped with the composite PEM show promising power densities and long‐term stability. Interestingly, the hybrid PEM can be fabricated continuously in large scale at challenging ~10 μm thickness via typical tape casting technique originated from their facile complexing strategy and the hybrids’ excellent mechanical properties. This work not only provides potential material systems for commercial PEMs, but also raises interest for the research on hybrid composites for PEMs.

Fabrication of Cellulose Acetate-Based Proton Exchange Membrane with Sulfonated SiO2 and Plasticizers for Microbial Fuel Cell Applications.

Developing a hybrid composite polymer membrane with desired functional and intrinsic properties has gained significant consideration in the fabrication of proton exchange membranes for microbial fuel cell applications. Among the different polymers, a naturally derived cellulose biopolymer has excellent benefits over synthetic polymers derived from petrochemical byproducts. However, the inferior physicochemical, thermal, and mechanical properties of biopolymers limit their benefits. In this study, we developed a new hybrid polymer composite of a semi-synthetic cellulose acetate (CA) polymer derivate incorporated with inorganic silica (SiO2) nanoparticles, with or without a sulfonation (-SO3H) functional group (sSiO2). The excellent composite membrane formation was further improved by adding a plasticizer (glycerol (G)) and optimized by varying the SiO2 concentration in the polymer membrane matrix. The composite membrane's effectively improved physicochemical properties (water uptake, swelling ratio, proton conductivity, and ion exchange capacity) were identified because of the intramolecular bonding between the cellulose acetate, SiO2, and plasticizer. The proton (H+) transfer properties were exhibited in the composite membrane by incorporating sSiO2. The composite CAG-2% sSiO2 membrane exhibited a higher proton conductivity (6.4 mS/cm) than the pristine CA membrane. The homogeneous incorporation of SiO2 inorganic additives in the polymer matrix provided excellent mechanical properties. Due to the enhancement of the physicochemical, thermal, and mechanical properties, CAG-sSiO2 can effectively be considered an eco-friendly, low-cost, and efficient proton exchange membrane for enhancing MFC performance.

Solid-State Characterization of Heteropolyacid-Phyllosilicate Complexes: Structural, Morphological and Thermal Properties

We have previously described the complex formation from a synthetic smectite clay, Sumecton SA (SSA), and the heteropolyacid (HPA), 12-phosphotungstic acid (PTA). Three new synthetic layered aluminosilicate clays of the smectite- [Lucentite SWN (SWN)] and (fluoro)mica-type [Tetrasilicic mica (TSM); Somasif ME100, (SME)] have been self-assembled with PTA, at a specific PTA-clay weight ratio of 5. New protogenic inorganic complexes have been prepared for the future fabrication of proton exchange membrane for fuel cell devices (PEMFC). Complex formation, thermal and structural properties of PTA-phyllosilicate complexes have been investigated using EDX, XRD, SEM, and DRIFT. EDX indicates that complexes incorporate a substantial amount of PTA (50-60% w/w) and that a moderate depletion of Mg2+ ions from octahedral layers of micas clays occurs during the process compared to smectite ones. In contrast, a significant amount of F is removed from the octahedral framework of the mica clays. DRIFT experiments indicate that the Keggin structure is preserved within all complexes and that complex formation predominantly involves the external oxygen (W-Od) of PTA. According to Patterson functions, coherence lengths - which reflect for the virgin clays the extent of the longitudinal platelet stacking (Lc) - of the two smectite clays (Lc ~25 Å) are significantly lower than for their analogous of the mica type (Lc = 180-225 Å). Clays in complexes are characterized by the loss of in-plane organization but are still partially ordered. The nature of the order is still speculative but could be related to the formation of a new inorganic PTA species formed during the complex formation. Compared to the virgin clays, the order of smectite complexes is maintained in the same range (Lc = 27-42 Å) while for mica complexes, coherence lengths are dramatically reduced to ~ 60 Å. All PTA-activated complexes contain a substantial amount of amorphous silica, which tends to increase when heated at temperatures above 280 oC. However, the Keggin structure within the complexes is at least stable up to 280 oC and even, for the most robust TSM complex, up to 450 oC.

Fabrication of proton exchange membrane for non-humidified fuel cells based on polyimide Matrimid® and hydrophobic protic ionic liquid

New proton exchange membrane based on polyimide Matrimid® (PI) and hydrophobic protic ionic liquid, 1-methylimidazolium bis(trifluoromethylsulfonyl)imide (MIM-TFSI), has been prepared by casting from methylene chloride/dimethylformamide solution. Infrared analysis revealed physicochemical interactions between 1-methylimidazolium cations and imide groups of PI. The results of mechanical testing indicate significantly reduced tensile strength of PI/MIM-TFSI composite membrane compared to neat polymer. Moreover, the dynamical mechanical analysis results revealed sharp drop in storage modulus (E´) of the polymer film above 60 °C. To improve the elastic properties of the membrane, PI was successively cross-linked with polyetheramine Jeffamine® D-2000 (10 mol. %) in methylene chloride/dimethylformamide solution, as well as in solid film at 100 °C. This approach allowed to prepare PI/Jeffamine/MIM-TFSI (70 wt. %) composite film which has an acceptable E' value of 210 MPa at 140 °C. According to thermal gravimetric analysis data, PI/Jeffamine/MIM-TFSI composite has a thermal degradation point (i.e. 5 % weight loss) of 286 °C. The ionic conductivity of PI/Jeffamine/MIM-TFSI composite membrane is around 10–4 S/cm at room temperature and reaches the minimal level of 10–3 S/cm, required for fuel cell applications, above 100 °C. Overall, the results of this study indicate that the cross-linking of polyimide Matrimid with flexible polyetheramine Jeffamine is an efficient approach for preparing dense composite membrane with high content of the protic ionic liquid. Such polymer-electrolyte membrane has the reasonable combination of good stiffness, thermal stability, and ionic conductivity and therefore is a promising candidate for use in fuel cells operating at elevated temperatures in water-free conditions.

Sterically Hindered Pyridine-Linked Sulfonated Polytriazoles: Fabrication of Membranes and Investigation of Single Fuel Cell Performance

The semifluorinated sulfonated polytriazoles could integrate the benefits of both enhanced proton conductivity and chemical stability, which makes them one of the best choices for the fabrication of proton exchange membranes (PEM) for fuel cell applications. Herein we report a series of semifluorinated sulfonated polytriazoles, prepared from 2,2′-hindered pyridine functionalized nonsulfonated diazide (PYFAZ) and dialkyne (PYAK). The degrees of sulfonation of the polytriazoles (PYPYSH-XX) were varied by using DSSAZ as one of the sulfonated diazide comonomer in the polymer synthesis. The polymers showed a weight-average molecular weight of up to 450 800 g·mol–1, and their chemical structures were confirmed by FTIR and NMR techniques. The solution cast membranes showed phase-separated morphology with well-defined hydrophilic and hydrophobic domains. The membranes were mechanically robust (tensile strength up to 65.5 MPa, Young modulus of 2.37 GPa), were thermally stable, and exhibited a very high oxidative stability of 48 h (PYPYSH-70). The elongation at the break of the membranes was above 13%, somewhat lower in comparison to that of Nafion-117. Nevertheless, it was possible to fabricate a good quality electrode membrane assembly. The membranes show proton conduction in the range of 95–184 mS·cm–1 (80 °C) and a power density of 599–966 mW·cm–2 (H2/O2) depending on their degree of sulfonation. All these results indicate the potential use of these membranes in PEMFCs.

Proton conducting membrane based on multifunctional interconnected copolymer containing 4,4′‐diaminodiphenylmethane‐aminoethyl piperazine with sulfonated polyethersulfone membrane for fuel cell application

AbstractThe facile fabrication of proton exchange membrane (PEM) by intermixing of aminoethylpiperazine monomer (AEP), diamino diphenylmethane (DDM) monomer, and AEP combine with varying compositions of DDM (2, 4, and 6 wt%) copolymer with sulfonated polyethersulfone (SPES) and polyamide‐imide (PAI) polymer matrix for fuel cell applications. The intermixing of AEP@DDM copolymer in the SPES/PAI matrix was confirmed by Fourier transform infrared spectroscopy (FTIR) and X‐ray diffraction spectroscopy (XRD) techniques. The physicochemical performance of fabricated PEM was analyzed by water uptake, ion exchange capacity (IEC), swelling ratio, thermal degradation, hydrolytic degradation, chemical and mechanical properties. The intermixing copolymer (AEP@DDM) has significantly suppressed the thermal and hydrolytic deterioration of the PEM. Furthermore, the PAI had noteworthy to improve the thermal and chemical stability of the membranes significantly. The proton conductivity of the SPES/PAI/AEP@DDM (6%) membrane was found to be 5.68 × 10−4 S cm−1 which is 104% higher than the pristine SPES membrane. Besides, the selectivity of SPES/PAI/DDM (6%) was also enhanced up to 80.34% compared to pristine SPES membrane. The inclusion of AEP@DDM in SPES/PAI enhanced the proton conductivity and contributed to the membrane structure's uniformity, as revealed from morphological studies. The AEP@DDM copolymer modification of SPES/PAI membrane has shown good stability, physicochemical property and can be considered as a promising membrane material for fuel cell application.

Improvement of proton conductivity of magnetically aligned phosphotungstic acid-decorated cobalt oxide embedded Nafion membrane

The fabrication of proton exchange membranes with a short conduction pathway in the direction of membrane thickness is desirable for fuel cell applications. In this study, a new nanohybrid additive (Co3O4-NH2/H3PW12O40; CAW) is synthesized, by anchoring phosphotungstic acid (H3PW12O40; HPW) on aminopropylsiloxane-functionalized cobalt oxide, and then it is incorporated into the Nafion (NF) matrix to prepare nanocomposite membranes by film casting from CAW dispersions in NF solutions. To obtain short-pathway proton-conducting channels, through the nanocomposite membranes drying process, a magnetic field is employed to align the nanohybrid particles in transversal (thickness) direction of the NF matrix. Furthermore, the alignment of nanohybrids is observed directly by scanning electron microscopy, and estimated indirectly by proton conductivity and methanol permeability values. It is found that alignment of nanohybrids in the NF matrix elevates the conductivity of proton as well as the permeability of methanol. The aligned NF/CAW nanocomposite membrane with 1 wt% of CAW reveals the highest proton conductivity of 211 mS cm−1 at 90 °C and 95% relative humidity, which is 39% higher than that of pure NF (152 mS cm−1). Interestingly, through the orientation of CAW, 76% improvement in the selectivity of the membranes is observed.

Electrospray Deposition: A Breakthrough Technique for Proton Exchange Membrane Fuel Cell Catalyst Layer Fabrication

This Spotlight article presents the state-of-the-art of electrospray deposition technique applied to the fabrication of proton exchange membrane fuel cell (PEMFC) components, mainly focusing on catalyst layers in gas diffusion electrodes. The atomization of a suspension of particles over a substrate under the influence of a strong electric field results in the growth of a film with macroporous morphology and many interesting properties. This so-called electrospray deposition has reported many noteworthy beneficial effects for the fabrication of the catalyst layers of gas diffusion electrodes of PEMFCs. The electrosprayed catalyst layers prepared from suspensions of catalyst particles and ionomers present a dendritic macroporous morphology with superhydrophobic character that improves the water management inside the cell and increases the performance by ∼20% with respect to standard electrodes prepared by airbrushing. Other interesting effects observed with electrosprayed catalyst layers are increased catalyst utilization and water absorption capabilities of the ionomer, improved performance under nonhumidified conditions, and a reduction in catalyst degradation. In addition, the electrospray deposition decreases platinum losses during fabrication thanks to the attractive electrostatic forces between the ion mist and the substrate compared with regular ink-based spray methods.

Amino- and Sulfonate-Functionalized Metal–Organic Framework for Fabrication of Proton Exchange Membranes with Improved Proton Conductivity

Metal–organic frameworks (MOFs) are emerging as highly promising candidates for the next-generation proton conductors. Particularly, the amine-containing as well as various acid-functionalized MOFs...

Combined Intrinsic and Extrinsic Proton Conduction in Robust Covalent Organic Frameworks for Hydrogen Fuel Cell Applications.

Developing new materials for the fabrication of proton exchange membranes (PEMs) for fuel cells is of great significance. Herein, a series of highly crystalline, porous, and stable new covalent organic frameworks (COFs) have been developed by a stepwise synthesis strategy. The synthesized COFs exhibit high hydrophilicity and excellent stability in strong acid or base (e.g., 12 m NaOH or HCl) and boiling water. These features make them ideal platforms for proton conduction applications. Upon loading with H3 PO4 , the COFs (H3 PO4 @COFs) realize an ultrahigh proton conductivity of 1.13×10-1 S cm-1 , the highest among all COF materials, and maintain high proton conductivity across a wide relative humidity (40-100 %) and temperature range (20-80 °C). Furthermore, membrane electrode assemblies were fabricated using H3 PO4 @COFs as the solid electrolyte membrane for proton exchange resulting in a maximum power density of 81 mW cm-2 and a maximum current density of 456 mA cm-2 , which exceeds all previously reported COF materials.

Combined Intrinsic and Extrinsic Proton Conduction in Robust Covalent Organic Frameworks for Hydrogen Fuel Cell Applications

AbstractDeveloping new materials for the fabrication of proton exchange membranes (PEMs) for fuel cells is of great significance. Herein, a series of highly crystalline, porous, and stable new covalent organic frameworks (COFs) have been developed by a stepwise synthesis strategy. The synthesized COFs exhibit high hydrophilicity and excellent stability in strong acid or base (e.g., 12 m NaOH or HCl) and boiling water. These features make them ideal platforms for proton conduction applications. Upon loading with H3PO4, the COFs (H3PO4@COFs) realize an ultrahigh proton conductivity of 1.13×10−1 S cm−1, the highest among all COF materials, and maintain high proton conductivity across a wide relative humidity (40–100 %) and temperature range (20–80 °C). Furthermore, membrane electrode assemblies were fabricated using H3PO4@COFs as the solid electrolyte membrane for proton exchange resulting in a maximum power density of 81 mW cm−2 and a maximum current density of 456 mA cm−2, which exceeds all previously reported COF materials.

Fabrication of proton exchange membranes and effect of sulfonated SiO2 (S-SiO2) in sulfonated polyether ether ketone (SPEEK) for fuel cells applications

The fabrication of composite proton exchange membrane from the sulfonated polyether ether ketone (SPEEK) and sulfonated SiO2 (S-SiO2) have been investigated for energy production. In this work, inorganic fillers have been incorporated successfully in the organic polymer matrix. The degree of sulfonation (DS) and ion exchange capacity (IEC) were measured by back titration method and observed around 46.4 % and 1.43 mmol/gm, respectively. DS and IEC were found is increase with the increase of the amount of S-SiO2 which reached to 56.5 % and 1.69 mmol/gm, respectively. Water uptake in percent was increased in the SPEEK/S-SiO2 membrane due to increasing the sulfuric acid groups (-SO3H), that lead to increasing the hydrophilic channels, the swelling ratio in percent was slightly increased. The proton conductivity of the SPEEK membrane was around 17.4 mS/cm and increased with increasing the amount of S-SiO2. The highest proton conductivity observed at SPEEK/0.3 S-SiO2 was around 53.7 mS/cm. suggesting its use in fuel cell for energy production.

Electrophoretic fabrication of proton exchange membranes in fuel cells

For the first time, the fabrication of proton exchange membranes in fuel cells via an electrophoretic deposition (EPD) method is demonstrated, taking extensively researched sulfonated poly(ether ether ketone) (SPEEK) membranes as a paradigm. The membranes are obtained via depositing SPEEK ionomers, dispersed in a mixed solvent consisting dimethylsulfoxide (DMSO) and water, onto the anodic electrode under different applied voltages ranging from 15 to 25 V. The electrodeposited membranes show a number of differences from cast SPEEK membranes, e.g. smaller ionic clusters, higher surface roughness, higher water uptake and higher dry density. Particularly, the SPEEK membrane electrodeposited at 25 V reaches a proton conductivity of 0.11 S cm−1 at 70 °C and 100% RH, remarkably surpassing its cast counterpart.

Development of a low temperature decal transfer method for the fabrication of proton exchange membrane fuel cells

Proton exchange membrane fuel cell (PEMFC) has reached the stage of early commercialization, with attention now focused on manufacturing process. In this study decal transfer as the common method of PEMFC fabrication is investigated systematically, and an effective low temperature decal transfer method (LTDM) is developed without using any chemical reagents, breaking layers, and high hot press temperatures. It is shown that this LTDM results in complete catalyst transfer yield from the decal substrate to the membrane without the formation of Nafion outer layer and delamination between the catalyst layer and membrane. Further, catalyst transfer yield is influenced by the type of substrate material, the deposition of the extra Nafion layer, and the hot press conditions. Among the seven inert substrates studied, fluorinated ethylene propylene (FEP) is shown to be the best due to its lower friction coefficient and lower contact angle (for the hydrofluoropolymers). The performance of the resulting PEMFCs is compared with the recent developments in low temperature decal method under the same fabrication and testing conditions, facilitating a solid comparison of the various methods.

A platinum-like behavior electrocatalyst and solid polymer electrolyte technique used on high concentration of electrochemical ozone water generation

This study presents an advanced ozone production process using the solid polymer electrolyte (SPE) technique, similar to the fabrication of proton exchange membrane fuel cell (PEMFC) membrane electrode assembly (MEA). Tungsten carbide and platinum on carbon black are coated on anode and cathode sides of a polymer membrane (Du Pont), respectively, to produce high concentration of ozone water. The water electrolysis of ozone generation requires a higher voltage than that of hydrogen production. On one hand, tungsten carbide, which is a platinum-like behavior electrocatalyst, plays a key role in preventing the MEA from corroding or oxidizing under high voltage. On the other hand, the carbon paper is replaced by a titanium porous disc to bear higher voltage. Moreover, an outstanding electronic control system can produce 1.37 ppm ozone water at atmosphere by adjusting the voltage range (6–10 V) with a current set to the maximum of 3 A for a household demand of ozone water generation.

Plasma-induced Styrene Grafting onto the Surface of Polytetrafluoroethylene Powder for Proton Exchange Membrane Application

Low-temperature plasma treatment was adopted to graft styrene onto polytetrafluoroethylene (PTFE) powder, which is widely used in the fabrication of proton exchange membrane (PEM). The grafted PTFE powder was sulfonated in chlorosulfonic acid and fabricated into a membrane, which was used as inexpensive PEM material for a proton exchange membrane fuel cell (PEMFC). Fourier transform infrared spectroscopy attenuated total reflection spectroscopy (FTIR-ATR) and X-ray photoelectron spectroscopy (XPS) analysis were used to characterize the structure of the sulfonated PTFE powder. The results showed that all the PTFE powders were successfully grafted by nitrogen plasma and then sulfonated under such experimental conditions. A scanning electron microscopy (SEM) image indicated that the fabricated membrane exhibits flat morphology and homogenous structure. The ion exchange capacity (IEC) of this kind of PEM was also investigated.

Synthesis and performance evaluation of a polymer mesh supported proton exchange membrane for fuel cell applications

Abstract A novel approach to the design and fabrication of proton exchange membrane (PEM) has been developed whereby a non-structural polymer fabricated with high proton exchange capacity was bound to an inert polymer matrix. The patented fabrication techniques used here allow greater flexibility in PEM design. Results related to proton exchange performance of these novel PEMs are presented here. The proton exchange material described herein is a ter-polymer composed of various ratios of monomers. These materials were bound to an inert ethylene–tetrafluoroethylene (ETFE) copolymer mesh that had been rendered adhesive using patented hydroxylation technique in a two-step water-borne process. The basic characteristics of the new membranes were compared to those of Nafion ® 212. An aqueous two-cell testing unit is utilized by which the rate of protons transferred from one cell through the membrane into the other cell was determined by monitoring the change in pH of the cells. Results indicated that the new membrane could transfer protons approximately 10 times faster per unit area compared to Nafion ® 212 under the test conditions utilized at 80 °C. In addition to improvement in induction time and reduced resistance, the new membrane conducts protons at reduced membrane water content compared to Nafion ® 212.

Novel Deposition of Pt∕C Nanocatalysts and Nafion® Solution on Carbon-Based Electrodes via Electrophoretic Process for PEM Fuel Cells

Nanosized platinum particles supported on carbon black carriers (Pt∕C) are popular for use in fabrication of proton exchange membrane fuel cells (PEMFCs). Here, an electrophoretic deposition (EPD) process is proposed to investigate the power performance of Pt∕C nanopowders onto various carbon-based electrodes for the PEMFC applications in a better controlled and cost-effective manner. Novel deposition of Pt∕C nanocatalysts and Nafion® solution via electrophoretic process give rise to higher deposition efficiency and a uniform distribution of catalyst and Nafion ionomer on the electrodes of PEMFCs. Preparation of an EPD suspension with good dispersivity is much desirable for an agreeable overall performance of catalyst coating in terms of types of organic solvents, milling processes, and use of pH adjusting agents and surfactants in the EPD suspension. The EPD suspension was prepared by sonication of mixture of Pt∕C nanopowders, Nafion solution and isopropyl alcohol, the optimal pH value of which was reached by using acetic acid or ammonium hydroxide. The colloidal stability of EPD suspension was achieved at pH ∼10 for an EPD suspension of either Pt∕C catalysts or mixture of Pt∕C catalysts and Nafion ionomer. A nicely distributed deposition of Pt∕C nanocatalysts and Nafion ionomer on both hydrophilic or hydrophobic carbon-based electrodes was successfully obtained by using Pt∕C concentration of 1.0g∕l, electrical field of 300V∕cm, and deposition time of 5min. Microstructural analysis results indicate that Pt∕C nanopowders not only embrace the entire surface of carbon fibers but also infiltrate into the gaps and voids in fiber bundles such that a higher contact area of the same loading of Pt∕C nanocatalysts through the EPD process is thus expected. At present, the EPD process can effectively save more of Pt catalyst loading on electrodes in PEMFC, as compared to conventional methods, such as screen printing, brushing, or spraying through the similar level of power performance for PEMFCs.