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Although the uses of alternative energy sources have been increased greatly in recent years, current major energy demand is still supplied from conventional fossil fuels such as oil, coal and natural gas. Considering the inevitable depletion of the world’s energy supply and the release of green-house in the earth’s atmosphere, it is necessary to look for an alternative source of fuel. Alkaline-anion-exchange membrane direct alcohol fuel cells (AAEM-DAFCs) are among the promising candidates as alternative power sources for both stationary and portable power applications. Due to the facile kinetics at both the cathode and the anode in alkaline media, the use of non-noble and low-cost material catalysts become feasible, which makes the AAEM-DAFCs a potentially low cost technology compared with proton exchange membrane (PEM) based DAFCs working in acidic media. Bioethanol has high energy density and is non-toxicity, easy to transport and can be distributed with the existing infrastructure. Bioethanol is a renewable bio-based liquid fuel that can be produced from several different biomass feedstock and conversion technologies. First generation bioethanol is produced by distillation from crops such as wheat, corn, sugar cane and sugar beet; however, this bioethanol production has limitation due to concerns about food price and land use impacts. Second generation bioethanol is produced from different types of lignocellulosic materials as substrate. Currently, only negligible amounts of second generation bioethanol are produced in several demo plants around the world that work industrially, but are not yet commercially feasible. In this work, the bioethanol was produced by diversity feed stocks, like food waste and cellulosic, away from expensive corn. The produced bioethanol may contain some impurities, such as acetic acid, lactic acid, phosphorus, maltotetraose (Dp4), glucose, maltose, fructose, glycerol, isomaltotriose (Dp3), sulfur and so on. Pd/C was a promising catalyst for the ethanol oxidation reaction (EOR) in alkaline media. Our earlier work indicated that the PdRu/C catalyst exhibited much higher initiate activity toward EOR than the Pd/C catalyst in fuel cell operation conditions. Therefore, we further study the tolerance of impurities in bioethanol on Pd/C and PdRu/C catalysts toward EOR in alkaline media and demonstrate their performance and stability in AAEM-DAFCs using bioethanol as the fuel. Acknowledgements We acknowledge financial supports from the National Science Foundation Partnerships for Innovation: Building Innovation Capacity (Contract 1317731).

Electrocatalysis of ethanol oxidation reactions (EORs) and methanol oxidation reactions (MORs) in alkaline media has gained great research interests due to the development of alkaline anion exchange membranes. The EOR and MORs kinetics are more facile in alkaline media than those in acid media. The most importantly, there are more choices of materials to be used as the electrocatalysts for the EOR or MOR since these materials are stable in the alkaline media, but not in the acid media. Although extensive research has been done worldwide related to electrocatalysis of EORs and MORs in both acid and alkaline media, the EOR or MOR mechanisms are still not well understood. It still remains as a major challenge of reducing the overpotentials of EORs and MORs in low temperature fuel cells. In this work, we aim to study effects of Pb on electrocatalysis of EORs and MORs on Pt/C catalysts in alkaline media. The commercial available Pt/C catalysts were performed electrochemical characterizations in a standard tri-electrode electrochemical cell with a graphite column serving as the counter electrode and a Hg/HgO/1.0 M OH- electrode (0.098 V vs. NHE) as the reference electrode in an argon-saturated or ethanol or methanol-contained 1 M NaOH solution without or with 1mM lead(II) acetate (Sigma-Aldrich) presented. The EOR or MOR activities of the catalysts were also characterized with a single direct alcohol fuel cell. The membrane electrode assemblies (MEA) with an active electrode area of 4.5 cm2 were comprised of a catalyst coated membrane (CCM), a Ni foam (Hohsen Corp.) as the anode backing layer and a TGP-H-090 carbon paper (Toray) as the cathode backing layer. The anode catalyst ink was prepared by mixing the catalyst with Nafion solution. The cathode catalyst ink was prepared by ultrasonicating 8mg MnO2 nanorod catalyst, 8 mg active carbon (BP2000, Cabot Corp. ) and the A4 ionomer (Tokuyama Co.). The catalyst/ionomer (Nafion or A4) weight ratio is kept at 80:20 in both anode and cathode. A fuel cell test system (Scribner Associates Model 850e) was used for controlling the cell temperature, cathode humidity, O2 flow rate. The temperature of the fuel cell was maintained with a tolerance of ± 0.2 °C. The anode solution flow rate was controlled ESI's MP2 micro peripump (elemental scientific Inc.) CV curves were obtained with the Pt/C in Ar-saturated 1.0 M NaOH or 1.0 M ethanol (or methanol) and 1.0 M NaOH solution without or with 1mM Pb2+ presented. From the CV curves obtained in the 1.0 M NaOH solutions, the Pb2+ presence in the solution was found to alter surface characteristics on Pt/C catalysts. The EOR and MOR activities were also affected accordingly. Both CV and chronoamperometry (CA) measurements indicate that the presence of Pb2+ in the solution leads to the increase of EOR and MOR kinetics on the Pt/C catalysts, agree with what have been reported. Detailed fuel cell characterizations with the Pt/C anode catalysts using fuels without and with 1mM Pb2+ presence were performed. Combining the electrochemical measurements and fuel cell test results, effects of Pb on the electrocatalysis of EOR and MOR on the Pt/C catalyst in alkaline media will be presented. Acknowledgements We acknowledge financial supports from the National Science Foundation (NSF) (Contract 1402422).

Electrocatalysis of ethanol oxidation reactions (EORs) in alkaline media has gained great research interests due to the development of alkaline anion exchange membranes. The EOR kinetics are more facile in alkaline media than those in acid media. The most importantly, there are more choices of materials to be used as the electrocatalysts for the EOR since these materials are stable in the alkaline media, but not in the acid media. Although extensive research has been done worldwide related to electrocatalysis of EORs in both acid and alkaline media, the EOR mechanisms are still not well understood. It still remains as a major challenge of reducing the overpotentials of EORs in low temperature fuel cells. The oxidation of ethanol in alkaline media is very complicated and involves many types of intermediates, such as C1 species (most likely COad and CHx,ad), OHad, CH3COad and other forms of acetaldehyde in alkaline media. Single metal catalysts are often found to perform much poorer than those modified with the second metal. “Multi-functional” electrocatalyst systems have been designed and tested for EORs. In this work, we aim to study effects of Pb on electrocatalysis of EORs on Pd/C and PdRu/C catalysts in alkaline media. Pd/C and Pd2Ru/C (the atomic ratio of Pd:Ru is 2:1) catalysts with 20 wt. % Palladium loading were prepared by an impregnation method. The morphologies of the catalysts were studied by transmission electron microscope (TEM) and x-ray diffraction (XRD) characterizations. Then the catalysts were performed electrochemical characterizations in a standard tri-electrode electrochemical cell with a graphite column serving as the counter electrode and a Hg/HgO/1.0 M OH- electrode (0.098 V vs. NHE) as the reference electrode in an argon-saturated or ethanol-contained 1 M NaOH solution without or with 1mM lead(II) acetate (Sigma-Aldrich) presented. The EOR activities of the catalysts were also characterized with a single direct ethanol fuel cell. The membrane electrode assemblies (MEA) with an active electrode area of 4.5 cm2 were comprised of a catalyst coated membrane (CCM), a Ni foam (Hohsen Corp.) as the anode backing layer and a TGP-H-090 carbon paper (Toray) as the cathode backing layer. The anode catalyst ink was prepared by mixing the 16mg catalyst (Pd/C and Pd2Ru/C) with Nafion solution. The cathode catalyst ink was prepared by ultrasonicating 8mg MnO2 nanorod catalyst, 8 mg active carbon (BP2000, Cabot Corp. ) and the A4 ionomer (Tokuyama Co.). The catalyst/ionomer (Nafion or A4) weight ratio is kept at 80:20 in both anode and cathode. A fuel cell test system (Scribner Associates Model 850e) was used for controlling the cell temperature, cathode humidity, O2 flow rate. The temperature of the fuel cell was maintained with a tolerance of ± 0.2 °C. The anode solution flow rate was controlled ESI's MP2 micro peripump (elemental scientific Inc.) CV curves were obtained with the Pd/C and Pd2Ru/C in Ar-saturated 1.0 M NaOH or 1.0 M ethanol and 1.0 M NaOH solution without or with 1mM Pb2+ presented. From the CV curves obtained in the 1.0 M NaOH solutions, the Pb2+ presence in the solution was found to alter surface characteristics on both Pd/C and PdRu/C catalysts. The EOR activities were also affected accordingly. Both CV and chronoamperometry (CA) measurements indicate that the presence of Pb2+ in the solution leads to the reduction of EOR kinetics on the Pd/C or PdRu/C catalysts, which are different from what were observed with Pt-based catalysts. Detailed fuel cell characterizations of these various catalysts were performed. Combining the electrochemical measurements and fuel cell test results, effects of Pb on the electrocatalysis of EOR on Pd/C and PdRu/C catalysts in alkaline media will be discussed.

In the recent years, bio-ethanol could be produced massively from various sources and has attracted great interests as an alternative fuel source in low temperature fuel cells. However, the bio-ethanol may contain some impurities, such as lactic acid, acetic acid, glucose, glycerol, maltose, fructose and so on, to contaminate the catalysts in the fuel cells. The objective of this work is to investigate the effects of impurities in bio-ethanol on the performance of Pd/C catalyst for the ethanol electro-oxidation reaction (EOR) in alkaline media. The electrocatalytic activities of Pd/C toward EOR with the addition of 0.01 M of various organic compounds were tested by cyclic voltammetry (CV). By comparing the EOR current at the corresponding potential, the presence of lactic acid and acetic acid was found to have little effects on the electrocatalytic activity of Pd/C toward EOR; however, the performance of Pd/C toward EOR get worse with the presence of glucose, glycerol, maltose, and fructose. The quasi-steady state current for EOR on the Pd/C catalyst was also measured by chronoamperometry (CA) measurements. The EOR current of the Pd/C decayed slowly with time. The steady currents at 0.5 V for EOR on Pd/C catalyst exhibit the order of EOR » EOR+0.01 M lactic acid > EOR+0.01 M acetic acid > EOR+0.01 M glucose > EOR+0.01 M glycerol > EOR+0.01 M maltose » EOR+0.01 M fructose. This trend is consistent with the CV test results. The tolerance of impurities in bio-ethanol on other catalysts toward the ethanol oxidation reaction in alkaline media will be also studied and discussed.

In the past few years, we have developed novel anion-exchange-membranes (AEMs) based on block copolymers for H2/O2 fuel cell applications [1-2] and discovered that dimensional stability of an AEM is very critical for achieving optimal performance in the fuel cells. Since ethanol is a non-toxic bio-fuel with a rather high energy density, it has attracted great attentions to be fed directly into polymeric electrolyte fuel cells. Ethanol oxidation reaction (EOR) in an alkaline media is much faster than that in an acid media and can be catalyzed on non-Pt catalysts. In this work, we aim to develop AEMs suitable for direct ethanol fuel cell (DEFC) applications. Four types of AEMs were prepared by varying "hybrid" SEBS-based copolymers. The swelling, water uptake, ionic conductivity, thermal stability and ion exchange capacity of the membranes were measured using the methods described in our previous work [1]. The impacts of ionic exchange capacity in the membranes on the performance of DEFCs were studied and compared with the commercial membrane (Tokuyama’s A201). DEFCs performances of various "hybrid" types of QSEBS membranes (Type I, II, III and IV) and commercial membrane (A201) will be presented. The correlations of the swelling, water uptake, ionic conductivity, thermal stability and ion exchange capacity of the membranes with the performance of DEFCs will be established and discussed. The key factors for developing AEMs for DEFC applications will be identified. References [1] L. Sun, J. Guo, J. Zhou, Q. Xu, D. Chu, R. Chen, Journal of Power Sources 202 (2012) 70– 77. [2] J. Zhou, J. Guo, D. Chu and R. Chen, Journal of power sources, 219 (2012) 272-279.

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Carbon supported PdRu catalysts with various Pd:Ru atomic ratios were studied by using X-ray diffraction (XRD), transmission electron microscopy (TEM), electrochemical half-cell tests, and the anion-exchange membrane direct ethanol fuel cell (AEM-DEFC) tests. Lower onset potential and peak potential and much higher steady state current for ethanol oxidation in alkaline media were observed on the bimetallic catalysts (PdxRuy/C) than on the Pd/C, while the activity for ethanol oxidation on the pure Ru/C was not noticeable. By using Pd/C anode catalysts and MnO2 cathode catalysts, AEM-DEFCs free from the expensive Pt catalyst were assembled. The AEM DEFC using the bimetallic Pd3Ru/C anode catalyst showed a peak power density as high as 176 mW cm-2 at 80 °C, about 1.8 times higher than that using the single metal Pd/C catalyst.

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Nickel-based catalysts with iron promotion were prepared by impregnation, tested in auto-thermal reforming (ATR) of ethanol for hydrogen production. The reaction results show a remarkable improved durability in catalytic activity as well as selectivity to hydrogen in ATR is obtained: Over the 10 wt.% iron-loading nickel catalyst, conversion of ethanol at 99.61 % and selectivity of hydrogen around 115 % are kept at 600 C during a 30-hour test, while that of iron-free sample decreases sharply from 85.10 % to 19.71 % on hydrogen selectivity within a 26-hour test. The improved durability is attributed to the synergistic effect of the NiAl2O4-FeAl2O4 mixed crystals that are more resistant to sintering and oxidation in the oxidative atmosphere of ATR.

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