Few layer graphene （FLG）, multi-walled carbon nanotubes （CNTs） and a nanotube-graphene composite （CNT-FLG） were used as supports for palladium nanoparticles. The catalysts, which were characterized by transmissi...Few layer graphene （FLG）, multi-walled carbon nanotubes （CNTs） and a nanotube-graphene composite （CNT-FLG） were used as supports for palladium nanoparticles. The catalysts, which were characterized by transmission electron microscopy, Raman spectroscopy and X-ray diffraction, were used as anodes in the electrooxidation of ethanol, ethylene glycol and glycerol in half cells and in passive direct ethanol fuel cells. Upon Pd deposition, a stronger interaction was found to occur between the metal and the nanotube-graphene composite and the particle size was significantly smaller in this material （6.3 nm）, comparing with nanotubes and graphene alone （8 and 8.4 nm, respectively）. Cyclic voltammetry experiments conducted with Pd/CNT, Pd/FLG and Pd/CNT-FLG in 10 wt% ethanol and 2 M KOH solution, showed high specific currents of 1.48, 2.29 and 2.51 mA-/zgp-d, respectively. Moreover, the results obtained for ethylene glycol and glycerol oxidation highlighted the excellent electrocatalytic activity of Pd/CNT-FLG in terms of peak current density （up to 3.70 mAgd for ethylene glycol and 1.84 mAfor glycerol, respectively）. Accordingly, Pd/CNT-FLG can be considered as the best performing one among the electrocatalysts ever reported for ethylene glycol oxidation, especially considering the low metal loading used in this work. Direct ethanol fuel cells at room temperature were studied by obtaining power density curves and undertaking galvanostatic experiments. The power density outputs using Pd/CNT, Pd/FLG and Pd/CNT-FLG were 12.1, 16.3 and 18.4 mW.cm-2, respectively. A remarkable activity for ethanol electrooxidation was shown by Pd/CNT-FLG anode catalyst. In a constant current experiment, the direct ethanol fuel cell containing Pd/CNT-FLG could continuously deliver 20 mA.cm-2 for 9.5 h during the conversion of ethanol into acetate of 30%, and the energy released from the cell was about 574 J.展开更多
Nanostructured interface is significant for the electrocatalysis process. Here we comparatively studied the electrooxidation of alcohols catalyzed by nanostructured palladium or palladium-cerium oxide. Two kinds of ac...Nanostructured interface is significant for the electrocatalysis process. Here we comparatively studied the electrooxidation of alcohols catalyzed by nanostructured palladium or palladium-cerium oxide. Two kinds of active sites were observed in palladium-cerium oxide system, attributing to the co-action of Pd-cerium oxide interface and Pd sites alone, by CO stripping technique, a structure-sensitive process generally employed to probe the active sites. Active sites resulting from the nanostructured interfacial contact of Pd and cerium oxide were confirmed by high resolution transmission electron microscopy and electrochemical CO stripping approaches. Electrochemical measurements of cyclic voltammetry and chronometry results demonstrated that Pd-cerium oxide catalysts exhibited much higher catalytic performances for alcohols oxidation than Pd alone in terms of activity, stability and anti-poisoning ability.The improved performance was probably attributed to the nanostructured active interface in which the catalytic ability from each component can be maximized through the synergistic action of bi-functional mechanism and electronic effect. The calculated catalytic efficiency of such active sites was many times higher than that of the Pd active sites alone. The present work showed the significance of valid nanostructured interface design and fabrication in the advanced catalysis system.展开更多
以农林废弃生物质气化合成混合醇工艺为对象,利用混合生命周期评估方法对百吨级系统进行环境影响分析。通过构建系统的工艺模型和收集生命周期资源消耗及排放清单,研究农林业、收储运和制取等各阶段的投入和排放特性,对棉秆、玉米秸秆...以农林废弃生物质气化合成混合醇工艺为对象,利用混合生命周期评估方法对百吨级系统进行环境影响分析。通过构建系统的工艺模型和收集生命周期资源消耗及排放清单,研究农林业、收储运和制取等各阶段的投入和排放特性,对棉秆、玉米秸秆、木屑和枝丫柴4种原料制取系统的环境影响特性进行分析,并与5万吨级系统进行比较。结果表明:百吨级系统生命周期化石能源消耗和温室气体排放分别在589~734 kJ/MJ混合醇和63.2~80.8 g CO_(2)eq/MJ混合醇范围内,制取阶段的电力消耗是最主要的影响因素,其次为系统设备设施投入,玉米秸秆混合醇的环境影响最大,这与原料碳含量低及混合醇收率低有关。展开更多
电催化反应过程涉及固、液、气传输以及电子和质子传导,为确保反应的顺利进行和提高催化剂中贵金属的利用率及延长催化剂的寿命,理想的电催化剂载体必须同时具备高比表面积、导电性好、合适的孔结构、耐腐蚀以及合适的表面基团等.为此,...电催化反应过程涉及固、液、气传输以及电子和质子传导,为确保反应的顺利进行和提高催化剂中贵金属的利用率及延长催化剂的寿命,理想的电催化剂载体必须同时具备高比表面积、导电性好、合适的孔结构、耐腐蚀以及合适的表面基团等.为此,碳载体的改性工作受到关注,常用的方法是通过酸、碱、氧化和高分子等手段改变载体的结构和表面性质,以期接近理想电催化剂载体的要求;同时在开发新型碳载体方面做了更大量的工作.本文简要评述了商品炭载体如碳黑Vulcan XC-72R以及其它的乙炔黑、黑珍珠-2000、Printex XE-2和Ketjen Black EC等碳材料在直接醇燃料电池中的应用,但对纳米碳纤维、碳纳米管、有序多孔碳、中间相碳小球、碳纳米角、碳纳米卷和碳气凝胶等新型碳载体则进行了较全面的评述.与商品碳载体相比,新型碳载体在一定程度上都表现出比XC-72R更优的性能,这主要是因为新型碳材料具有特殊的结构、更高的结晶性能(导电性)和更好的传质能力.展开更多
基金supported by the MATTM (Italy) for the PIRODE Project No 94the MSE for the PRIT Project Industria 2015the MIUR (Italy) for the FIRB 2010 Project RBFR10J4H7 002 and HYDROLAB2
文摘Few layer graphene （FLG）, multi-walled carbon nanotubes （CNTs） and a nanotube-graphene composite （CNT-FLG） were used as supports for palladium nanoparticles. The catalysts, which were characterized by transmission electron microscopy, Raman spectroscopy and X-ray diffraction, were used as anodes in the electrooxidation of ethanol, ethylene glycol and glycerol in half cells and in passive direct ethanol fuel cells. Upon Pd deposition, a stronger interaction was found to occur between the metal and the nanotube-graphene composite and the particle size was significantly smaller in this material （6.3 nm）, comparing with nanotubes and graphene alone （8 and 8.4 nm, respectively）. Cyclic voltammetry experiments conducted with Pd/CNT, Pd/FLG and Pd/CNT-FLG in 10 wt% ethanol and 2 M KOH solution, showed high specific currents of 1.48, 2.29 and 2.51 mA-/zgp-d, respectively. Moreover, the results obtained for ethylene glycol and glycerol oxidation highlighted the excellent electrocatalytic activity of Pd/CNT-FLG in terms of peak current density （up to 3.70 mAgd for ethylene glycol and 1.84 mAfor glycerol, respectively）. Accordingly, Pd/CNT-FLG can be considered as the best performing one among the electrocatalysts ever reported for ethylene glycol oxidation, especially considering the low metal loading used in this work. Direct ethanol fuel cells at room temperature were studied by obtaining power density curves and undertaking galvanostatic experiments. The power density outputs using Pd/CNT, Pd/FLG and Pd/CNT-FLG were 12.1, 16.3 and 18.4 mW.cm-2, respectively. A remarkable activity for ethanol electrooxidation was shown by Pd/CNT-FLG anode catalyst. In a constant current experiment, the direct ethanol fuel cell containing Pd/CNT-FLG could continuously deliver 20 mA.cm-2 for 9.5 h during the conversion of ethanol into acetate of 30%, and the energy released from the cell was about 574 J.
基金supported by the National Natural Science Foundation of China (21603041)the Priority Academic Program Development of Jiangsu Higher Education Institution
文摘Nanostructured interface is significant for the electrocatalysis process. Here we comparatively studied the electrooxidation of alcohols catalyzed by nanostructured palladium or palladium-cerium oxide. Two kinds of active sites were observed in palladium-cerium oxide system, attributing to the co-action of Pd-cerium oxide interface and Pd sites alone, by CO stripping technique, a structure-sensitive process generally employed to probe the active sites. Active sites resulting from the nanostructured interfacial contact of Pd and cerium oxide were confirmed by high resolution transmission electron microscopy and electrochemical CO stripping approaches. Electrochemical measurements of cyclic voltammetry and chronometry results demonstrated that Pd-cerium oxide catalysts exhibited much higher catalytic performances for alcohols oxidation than Pd alone in terms of activity, stability and anti-poisoning ability.The improved performance was probably attributed to the nanostructured active interface in which the catalytic ability from each component can be maximized through the synergistic action of bi-functional mechanism and electronic effect. The calculated catalytic efficiency of such active sites was many times higher than that of the Pd active sites alone. The present work showed the significance of valid nanostructured interface design and fabrication in the advanced catalysis system.
文摘以农林废弃生物质气化合成混合醇工艺为对象,利用混合生命周期评估方法对百吨级系统进行环境影响分析。通过构建系统的工艺模型和收集生命周期资源消耗及排放清单,研究农林业、收储运和制取等各阶段的投入和排放特性,对棉秆、玉米秸秆、木屑和枝丫柴4种原料制取系统的环境影响特性进行分析,并与5万吨级系统进行比较。结果表明:百吨级系统生命周期化石能源消耗和温室气体排放分别在589~734 kJ/MJ混合醇和63.2~80.8 g CO_(2)eq/MJ混合醇范围内,制取阶段的电力消耗是最主要的影响因素,其次为系统设备设施投入,玉米秸秆混合醇的环境影响最大,这与原料碳含量低及混合醇收率低有关。
文摘电催化反应过程涉及固、液、气传输以及电子和质子传导,为确保反应的顺利进行和提高催化剂中贵金属的利用率及延长催化剂的寿命,理想的电催化剂载体必须同时具备高比表面积、导电性好、合适的孔结构、耐腐蚀以及合适的表面基团等.为此,碳载体的改性工作受到关注,常用的方法是通过酸、碱、氧化和高分子等手段改变载体的结构和表面性质,以期接近理想电催化剂载体的要求;同时在开发新型碳载体方面做了更大量的工作.本文简要评述了商品炭载体如碳黑Vulcan XC-72R以及其它的乙炔黑、黑珍珠-2000、Printex XE-2和Ketjen Black EC等碳材料在直接醇燃料电池中的应用,但对纳米碳纤维、碳纳米管、有序多孔碳、中间相碳小球、碳纳米角、碳纳米卷和碳气凝胶等新型碳载体则进行了较全面的评述.与商品碳载体相比,新型碳载体在一定程度上都表现出比XC-72R更优的性能,这主要是因为新型碳材料具有特殊的结构、更高的结晶性能(导电性)和更好的传质能力.
