Herein,ionomer-free amorphous iridium oxide(IrO_(x))thin electrodes are first developed as highly active anodes for proton exchange membrane electrolyzer cells(PEMECs)via low-cost,environmentally friendly,and easily s...Herein,ionomer-free amorphous iridium oxide(IrO_(x))thin electrodes are first developed as highly active anodes for proton exchange membrane electrolyzer cells(PEMECs)via low-cost,environmentally friendly,and easily scalable electrodeposition at room temperature.Combined with a Nafion 117 membrane,the IrO_(x)-integrated electrode with an ultralow loading of 0.075 mg cm^(-2)delivers a high cell efficiency of about 90%,achieving more than 96%catalyst savings and 42-fold higher catalyst utilization compared to commercial catalyst-coated membrane(2 mg cm^(-2)).Additionally,the IrO_(x)electrode demonstrates superior performance,higher catalyst utilization and significantly simplified fabrication with easy scalability compared with the most previously reported anodes.Notably,the remarkable performance could be mainly due to the amorphous phase property,sufficient Ir^(3+)content,and rich surface hydroxide groups in catalysts.Overall,due to the high activity,high cell efficiency,an economical,greatly simplified and easily scalable fabrication process,and ultrahigh material utilization,the IrO_(x)electrode shows great potential to be applied in industry and accelerates the commercialization of PEMECs and renewable energy evolution.展开更多
Large scale zigzag zinc blende single crystal ZnS nanowires have been successfully synthesized during a vapor phase growth process together with a small yield of straight wurtzite single crystal ZnS nanowires.AuPd all...Large scale zigzag zinc blende single crystal ZnS nanowires have been successfully synthesized during a vapor phase growth process together with a small yield of straight wurtzite single crystal ZnS nanowires.AuPd alloy nanoparticles were utilized to catalyze a vapor-solid-solid growth process of both types of ZnS nanowires,instead of the more common vapor-liquid-solid growth process.Surprisingly,the vapor-phase grown zigzag zinc blende ZnS nanowires are metastable under high-energy electron irradiation in a transmission electron microscope,with straight wurtzite nanowires being much more stable.Upon exposure to electron irradiation,a wurtzite ZnO nanoparticle layer formed on the zigzag zinc blende ZnS nanowire surface with concomitant displacement damage.Both electron inelastic scattering and surface oxidation as a result of electron-beam heating occur during this structure evolution process.When prolonged higher-voltage electron irradiation was applied,local zinc blende ZnS nanowire bodies evolved into ZnS-ZnO nanocables,and dispersed ZnS-ZnO nanoparticle networks.Random AuPd nanoparticles were observed distributed on zigzag ZnS nanowire surfaces,which might be responsible for a catalytic oxidation effect and speed up the surface oxidation-induced structure evolution.展开更多
基金the support from the U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy (EERE) under the Hydrogen and Fuel Cell Technologies Office Awards DE-EE0008426 and DE-EE0008423National Energy Technology Laboratory under Award DEFE0011585.
文摘Herein,ionomer-free amorphous iridium oxide(IrO_(x))thin electrodes are first developed as highly active anodes for proton exchange membrane electrolyzer cells(PEMECs)via low-cost,environmentally friendly,and easily scalable electrodeposition at room temperature.Combined with a Nafion 117 membrane,the IrO_(x)-integrated electrode with an ultralow loading of 0.075 mg cm^(-2)delivers a high cell efficiency of about 90%,achieving more than 96%catalyst savings and 42-fold higher catalyst utilization compared to commercial catalyst-coated membrane(2 mg cm^(-2)).Additionally,the IrO_(x)electrode demonstrates superior performance,higher catalyst utilization and significantly simplified fabrication with easy scalability compared with the most previously reported anodes.Notably,the remarkable performance could be mainly due to the amorphous phase property,sufficient Ir^(3+)content,and rich surface hydroxide groups in catalysts.Overall,due to the high activity,high cell efficiency,an economical,greatly simplified and easily scalable fabrication process,and ultrahigh material utilization,the IrO_(x)electrode shows great potential to be applied in industry and accelerates the commercialization of PEMECs and renewable energy evolution.
基金The authors are grateful for the financial support from the University of Connecticut New Faculty start-up funds,and the University of Connecticut Large Faculty Research GrantAcknowledgement is also made to the Donors of the American Chemical Society Petroleum Research Fund for partial support of this research.
文摘Large scale zigzag zinc blende single crystal ZnS nanowires have been successfully synthesized during a vapor phase growth process together with a small yield of straight wurtzite single crystal ZnS nanowires.AuPd alloy nanoparticles were utilized to catalyze a vapor-solid-solid growth process of both types of ZnS nanowires,instead of the more common vapor-liquid-solid growth process.Surprisingly,the vapor-phase grown zigzag zinc blende ZnS nanowires are metastable under high-energy electron irradiation in a transmission electron microscope,with straight wurtzite nanowires being much more stable.Upon exposure to electron irradiation,a wurtzite ZnO nanoparticle layer formed on the zigzag zinc blende ZnS nanowire surface with concomitant displacement damage.Both electron inelastic scattering and surface oxidation as a result of electron-beam heating occur during this structure evolution process.When prolonged higher-voltage electron irradiation was applied,local zinc blende ZnS nanowire bodies evolved into ZnS-ZnO nanocables,and dispersed ZnS-ZnO nanoparticle networks.Random AuPd nanoparticles were observed distributed on zigzag ZnS nanowire surfaces,which might be responsible for a catalytic oxidation effect and speed up the surface oxidation-induced structure evolution.
