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Catalyst layers (CLs) with spatially ordered structure can improve mass transport of reactants/products, which is essential for the high performance of polymer electrolyte membrane fuel cells (PEMFCs). In this study, aligned polyaniline (PANI) nanorods grown on gas diffusion layers by in situ polymerization are used as supports for platinum to fabricate ordered CLs. The length and diameter of the PANI nanorods can be controlled by optimizing the reaction temperatures or the aniline concentrations during the in situ polymerization process. With the optimized aligned PANI nanorods as supports of cathode, the mass specific power density of the PEMFC reaches 2.5 kW g Pt −1 , which is 21% higher than that of the conventional PEMFC without PANI. This improvement can be attributed to the reduced oxygen transport resistance revealed by oxygen gain and electrochemical impedance spectroscopy. [ABSTRACT FROM AUTHOR]

The cross-linked and alkali stable alkaline anion exchange membranes (AAEMs) based on 1,2-dimethylimidazolium (proved to be much more stable than C2-unsubstituted imidazolium cation) were prepared by a hot-pressing method. The properties of these membranes, e.g., water uptake, swelling degree, ion-exchange capacity, conductivity and thermal and chemical stability, were characterized systematically. The swelling degree of the membranes decreases with the decrease of the amount of 1,2-dimethylimidazolium salt, up to 5.8%. The membranes are thermally stable below 200 °C. Alkaline direct methanol fuel cell (ADMFC) fabricated by using CoO x /C as the cathode catalyst and PtRu/C as the anode catalyst presents a promising performance with the peak power density of 12.7 mW cm −2 at a current density of 45 mA cm −2 , indicating that the 1,2-dimethylimidazolium-functionalized AAEMs are promising for the application in ADMFCs. [ABSTRACT FROM AUTHOR]

Abstract: A Pt-Nafion/C catalyst is synthesized through a modified ion-exchange method, in which [Pt(NH3)2]2+ cations exchange with H+ ions of Nafion/C composites and are reduced by H2. Based on the results from transmission electron microscopy and inductively coupled plasma atomic emission spectrometry, it is found that the average size of Pt particles is around 2.3 nm and the Pt loading is about 1.8 wt% in the Pt-Nafion/C catalyst. Although the Pt mass activities (MAs) toward oxygen reduction reaction tested in half cells are similar, when used as cathode catalyst for a direct methanol fuel cell, the Pt MA as high as 4.36 A mgPt −1 are achieved for the Pt-Nafion/C catalyst at 825 mV, which is 6 times higher than that of the Pt/C catalyst. The enhanced Pt utilization could be attributed to the defined location of Pt nanoparticles in the triple phase zones in electrode. [Copyright &y& Elsevier]

Abstract: A new anion exchange membrane was synthesized by a green and facile route---chemically grafting polybenzimidazole (PBI) membrane with BrCH2CH3. The obtained membrane was characterized by means of ex-situ and in-situ tests (EDX, FTIR, AC impedance, single cell test and so on). The results suggested that the group of –CH2CH3 was successfully grafted onto N atom within PBI backbone, while with Br− as counter ion. The corresponding ionic conductivity and ethanol permeability were about 0.022 Scm−1 and 5.24 × 10−8 cm2s−1, respectively. Finally, single cell test suggested that air-breathing alkaline direct ethanol fuel cell with quaternized PBI membrane can deliver a peak power density of about 11 mWcm−2 even at ambient temperature of 13 °C, which was better than those of air-breathing alkaline direct methanol fuel cell in literatures. In addition, a possible reaction mechanism was also proposed and discussed. [Copyright &y& Elsevier]

Abstract: A polymer electrolyte membrane for alkaline direct ethanol fuel cell (ADEFC) was prepared by dipping Nafion112 membrane into KOH solution for some time at room temperature. The obtained membrane (Nafion112/KOH) exhibited higher mechanical properties and thermal stability than Nafion112 membrane. The ionic conductivity of Nafion112/KOH in 1 M, 2 M and 6 M KOH solutions was 0.011 S/cm, 0.026 S/cm, 0.032 S/cm, respectively, depending on internal OH− concentration and the volume fraction of the internal aqueous phase. Single cell performance suggested that active ADEFC with Nafion112/KOH membrane can deliver a peak power density of 58.87 mW/cm2 at 90 °C, meanwhile, it can stably run for at least 12 h above 0.2 V. On the other hand, Pt-free air breathing ADEFC with Nafion112/KOH can output a peak power density of 11.5 mW/cm2 at 60 °C, and the corresponding lifetime was as long as 473 h above 0.3 V. [Copyright &y& Elsevier]

Abstract: In this paper, Fe2O3–SO4 2−/Nafion® composite membranes were prepared by a solution casting method. The physico-chemical properties of composite membranes were characterized by X-ray diffraction (XRD), SEM–EDX and thermogravimetric analysis (TGA). The water uptake ability, proton conductivity, and methanol permeability of the composite membranes were evaluated and compared with the recast Nafion® membrane. The results showed that the proton conductivity and the water uptake of the composite membranes were slightly higher than that of the recast Nafion® membrane. The composite membrane containing 5 wt.% Fe2O3–SO4 2- showed superior ability to suppress methanol crossover, and it further improved the direct methanol fuel cell (DMFC) performances with both 1 M and 5 M methanol feeding, compared with the recast Nafion® membrane. The preliminary 30 h lifetime test of the DMFC with the composite membrane with 5% Fe2O3–SO4 2 − indicated that the composite membrane is stable working at the real DMFC operating conditions at least during the test. These results suggest the applicability of the composite membranes in DMFCs. [Copyright &y& Elsevier]

Abstract: The effect of hydrous RuO2 (RuO2·xH2O) in anode on the performance of direct methanol fuel cells (DMFCs) was examined by voltammetry, methanol stripping analysis, electrochemical impedance spectroscopy, polarization measurement and chronopotentiometry. The results showed that, compared with the DMFC with conventional structures, the dynamic response and quasi-steady state performance of the RuO2·xH2O-introduced DMFCs were significantly improved. The DMFC with RuO2·xH2O layer (ROL) sandwiched between anode catalyst layer and gas diffusion layer exhibited better quasi-steady state performance than those either with ROL sandwiched between anode catalyst layer and electrolyte membrane or with RuO2·xH2O uniformly distributed in anode catalyst layer. The maximum power density of the DMFC with this novel structure was 16% higher than the DMFC with the conventional structure. Moreover, the dynamic response of this RuO2·xH2O-introduced cell was more stable during 250-hour of operation when compared with that of the conventional cell. [ABSTRACT FROM AUTHOR]

A high performance polymer electrolyte thermogalvanic cell, which converts thermal energy to electrical energy directly, is transformed from a proton exchange membrane fuel cell. The transform is realized by connecting the anode and cathode chamber with a gas tube and filling hydrogen to both chambers. Provided a heat flux through the cell, hydrogen is consumed in the cold side and regenerated in the hot side while circulating in two chambers during operation. The Seebeck coefficient is 0.531 mV K −1 at a cold side temperature of 60.0 °C and the maximum power density could reach up to 20 μW cm −2 with a temperature difference of 15.3 °C between two electrodes. [ABSTRACT FROM AUTHOR]

Abstract: Gas diffusion layers (GDLs) of direct methanol fuel cells (DMFCs), consisting of a microporous layer (MPL) and a back layer (BL), influence the cell performance and stability significantly due to the critical function that the GDL undertook, i.e., distribution of reactants and removal of the products in electrodes. The hydrophilic/hydrophobic properties of the GDLs are required to tailor to the transport/transfer of reactants/products depending on a specific electrode reaction. One important way to adjust the hydrophobic/hydrophilic properties of GDLs is to vary PTFE content in GDLs. In this paper, we employ infrared spectroscopy technique, specifically, diffuse reflection (DR) method and attenuation total reflection (ATR) method, to determine the PTFE content in both MPLs and BLs quantitatively by comparing the measured C-F intensity with the pre-calibrated standard plots. Compared to the ATR method, the DR method takes advantages of sensitivity, wide range and precision. By the DR method, we succeed in observing that PTFE in MPLs migrates to BLs, consistent with the corresponding EDX results for a sample experienced 600 h lifetime test, suggesting DR method an effective approach to determine quantitatively the hydrophilic/hydrophobic properties of both MPLs and BLs. [Copyright &y& Elsevier]

Abstract: In the present study, a method based on transmission-line mode for a porous electrode was used to measure the ionic resistance of the anode catalyst layer under in situ fuel cell operation condition. The influence of Nafion content and catalyst loading in the anode catalyst layer on the methanol electro-oxidation and direct methanol fuel cell (DMFC) performance based on unsupported Pt–Ru black was investigated by using the AC impedance method. The optimal Nafion content was found to be 15wt% at C. The optimal Pt–Ru loading is related to the operating temperature, for example, about 2.0mg/cm for C, 3.0mg/cm for C. Over these values, the cell performance decreased due to the increases in ohmic and mass transfer resistances. It was found that the peak power density obtained was 217mW/cm with optimal catalyst and Nafion loading at C using oxygen. [Copyright &y& Elsevier]

In this work, a high-specific-energy magnesium/water battery (Mg/H 2 O battery) combining Mg oxidation with hydrogen evolution reaction (HER) is developed for full-depth ocean application. With the optimized platinum loading associated with moderate Ni(OH) 2 on nickel foam, the performance can be increased obviously. Coupled with AZ91 Mg alloy anode, the specific energy of Mg/H 2 O battery reaches a dramatic value of 1003 W h kg −1 . Moreover, ultrahigh pressure of 1100 bar in the deep-sea simulated condition brings negligible effects on the performance of battery and electrodes. The influence of low temperature can be reduced to an acceptable level under the application at low discharge current density. Stable discharge of the battery for 100 days is also obtained. This work provides a new idea to supply power source with high specific energy, excellent environment adaptability, good safety and low cost for underwater application. [ABSTRACT FROM AUTHOR]

Abstract: Vulcan XC-72R, Ketjen Black EC 300J and Black Pearls 2000 carbon blacks were used as the additive in Pt black cathode catalyst layer to investigate the effect on direct methanol fuel cell (DMFC) performance. The carbon blacks, Pt black catalyst and catalyst inks were characterized by N2 adsorption and scanning transmission electron microscopy (STEM) with Energy dispersive X-ray (EDX) spectroscopy. The cathode catalyst layers without and with carbon black additive were characterized by scanning electron microscopy, EDX, cyclic voltammetry and current-voltage curve measurements. Compared with Vulcan XC-72R and Black Pearls 2000, Ketjen Black EC 300J was more beneficial to increase the electrochemical surface area and DMFC performance of the cathode catalyst layer. The cathode catalyst layer with Ketjen Black EC 300J additive was kept intimately binding with the Nafion membrane after 360 h stability test of air-breathing DMFC. [ABSTRACT FROM AUTHOR]