Properties of Si3N4/Ni electroplated nanocomposite such as corrosion current density after long time immersion,roughness of obtained layer and distribution of nanometric particulates were studied.Other effective facto...Properties of Si3N4/Ni electroplated nanocomposite such as corrosion current density after long time immersion,roughness of obtained layer and distribution of nanometric particulates were studied.Other effective factors for fabrication of nanocomposite coatings were fixed for better studying the effect of the average size of nanoparticulates.The effects of the different average size of nanometric particulates(ASNP)from submicron scale(less than 1μm)to nanometric scale(less than 10 nm)were studied.The nanostructures of surfaces were examined by scanning electron microscopy(SEM),transmission electron microscopy(TEM)and atomic force microscopy(AFM).Corrosion rates of the coatings were determined using the Tafel polarization test.It is seen that decreasing the ASNP will lead to lower corrosion current densities;however,in some cases,pitting phenomena are observed.The roughness illustrates a minimum level while the distribution of nanometric particulates is more uniform by decreasing the ASNP.The effects of pulsed current on electrodeposition(frequency,duty cycle)and concentration of nanoparticulates in electrodeposition bath on trend of obtained curves have been discussed.Response surface methodology was applied for optimizing the effective operating conditions of coatings.The levels studied were frequency range between 1 000 and 9 000 Hz,duty cycle between 10%and 90%and concentration of nanoparticulates of 10-90 g/L.展开更多
Over the past few years, electrocatalysis for the oxygen reduction reaction in alkaline solutions has undergone tremendous advances, and non-precious metal catalysts are of prime interest. In this study, we present a ...Over the past few years, electrocatalysis for the oxygen reduction reaction in alkaline solutions has undergone tremendous advances, and non-precious metal catalysts are of prime interest. In this study, we present a highly promising CoO@Co/N-C （where N-C represents a N-doped carbon material） catalyst, achieving an onset potential of 0.99 V （versus the reversible hydrogen electrode （RHE）） and a limiting current density of 7.07 mA-cm-2 （at 0.3 V versus RHE） at a rotation rate of 2,500 rpm in an O2-saturated 0.1 M KOH solution, comparable to a commercial Pt/C catalyst. The H2--O2 alkaline fuel cell test of CoO@Co/N-C as the cathode reveals a maximum power density of 237 mW.cm 2. Detailed investigation clarifies that a synergistic effect, induced by C-N, Co-N-C, and CoO/Co moieties, is responsible for the bulk of the gain in catalytic activity.展开更多
Osmotic energy between river water and seawater has attracted interest as a new source of sustainable energy.Nanofluidic membranes in a reverse electrodialysis configuration can capture energy from salinity gradients....Osmotic energy between river water and seawater has attracted interest as a new source of sustainable energy.Nanofluidic membranes in a reverse electrodialysis configuration can capture energy from salinity gradients.However,current membrane materials suffer from high resistances,low stabilities,and low charge densities,which limit their further application.Here,we designed a high-performance nanofluidic membrane using carboxylic cellulose nanofibers functionalized with graphene oxide nanolamellas with cement-and-pebble microstructures and stable skeletons for enhanced ion transmembrane transport.By mixing artificial river water and seawater,the composite membrane achieved a high output power density up to 5.26 W m^(−2).Additionally,the membrane had an excellent acid resistance,which enabled long-term use with over 67 W m^(−2) of power density.The performance of this composite membrane benefited from the mechanically strong cellulose fibers and the bonding between nanofibers and nanolamellas.In this work,we highlight promising directions in industrial waste treatment using energy extracted from chemical potential gradients.展开更多
We reported a facile and robust one-pot wet chemistry strategy to achieve the growth of uniform three dimensional（3D） MoSe_2 ultrathin nanostructures on graphene nanosheets to form high quality MoSe_2/rGO hybrid nan...We reported a facile and robust one-pot wet chemistry strategy to achieve the growth of uniform three dimensional（3D） MoSe_2 ultrathin nanostructures on graphene nanosheets to form high quality MoSe_2/rGO hybrid nanostructures.Owing to the graphene as a support,it can significantly prevent the aggregation of MoSe_2 and the distribution of MoSe_2 on graphene was highly uniform.Importantly,due to the unique structures,the as-harvested MoSe_2/rGO hybrid exhibited excellent electrochemical performance as anode materials for sodium-ion battery（SIB）.When evaluated in a half cell system,the MoSe_2/rGO hybrid nanostructures could deliver a capacity of 200.2 mA h g^（-1） at8 A g^（-1） and maintain a capacity of 230.1 mA h g^（-1） over 100 cycles at 5 A g^（-1）.When coupled with Na_3V_2（PO_4）_3 cathode in a full cell system,the material could deliver a discharge capacity of 363.1 mA h g^（-1） at the current density of 0.5 A g^（-1）.Moreover,a discharge capacity of 56.4 mA h g^（-1） could be achieved even at a high current density of 10 A g^（-1）,which clearly suggested the high power capability of MoSe_2/rGO hybrid nanostructures for sodium ion energy storage.展开更多
Powder metallurgy was used to fabricate carbon nanotube(CNT) field emission cathodes.CNTs and tin(Sn) powder were blended,compacted and sintered.After polishing and etching,CNTs were exposed and protruded from the met...Powder metallurgy was used to fabricate carbon nanotube(CNT) field emission cathodes.CNTs and tin(Sn) powder were blended,compacted and sintered.After polishing and etching,CNTs were exposed and protruded from the metal surface.CNTs were embedded into the Sn matrix,which acted as stable field emitters. The J-E curves show excellent field emission properties,such as low turn-on field of 2.8 V/μm,high emission current density and good current stability.展开更多
文摘Properties of Si3N4/Ni electroplated nanocomposite such as corrosion current density after long time immersion,roughness of obtained layer and distribution of nanometric particulates were studied.Other effective factors for fabrication of nanocomposite coatings were fixed for better studying the effect of the average size of nanoparticulates.The effects of the different average size of nanometric particulates(ASNP)from submicron scale(less than 1μm)to nanometric scale(less than 10 nm)were studied.The nanostructures of surfaces were examined by scanning electron microscopy(SEM),transmission electron microscopy(TEM)and atomic force microscopy(AFM).Corrosion rates of the coatings were determined using the Tafel polarization test.It is seen that decreasing the ASNP will lead to lower corrosion current densities;however,in some cases,pitting phenomena are observed.The roughness illustrates a minimum level while the distribution of nanometric particulates is more uniform by decreasing the ASNP.The effects of pulsed current on electrodeposition(frequency,duty cycle)and concentration of nanoparticulates in electrodeposition bath on trend of obtained curves have been discussed.Response surface methodology was applied for optimizing the effective operating conditions of coatings.The levels studied were frequency range between 1 000 and 9 000 Hz,duty cycle between 10%and 90%and concentration of nanoparticulates of 10-90 g/L.
文摘Over the past few years, electrocatalysis for the oxygen reduction reaction in alkaline solutions has undergone tremendous advances, and non-precious metal catalysts are of prime interest. In this study, we present a highly promising CoO@Co/N-C （where N-C represents a N-doped carbon material） catalyst, achieving an onset potential of 0.99 V （versus the reversible hydrogen electrode （RHE）） and a limiting current density of 7.07 mA-cm-2 （at 0.3 V versus RHE） at a rotation rate of 2,500 rpm in an O2-saturated 0.1 M KOH solution, comparable to a commercial Pt/C catalyst. The H2--O2 alkaline fuel cell test of CoO@Co/N-C as the cathode reveals a maximum power density of 237 mW.cm 2. Detailed investigation clarifies that a synergistic effect, induced by C-N, Co-N-C, and CoO/Co moieties, is responsible for the bulk of the gain in catalytic activity.
基金supported by the National Key R&D Program of China(2017YFA0206904 and 2017YFA0206900)the National Natural Science Foundation of China(21625303,22122207,2190528721988102)。
文摘Osmotic energy between river water and seawater has attracted interest as a new source of sustainable energy.Nanofluidic membranes in a reverse electrodialysis configuration can capture energy from salinity gradients.However,current membrane materials suffer from high resistances,low stabilities,and low charge densities,which limit their further application.Here,we designed a high-performance nanofluidic membrane using carboxylic cellulose nanofibers functionalized with graphene oxide nanolamellas with cement-and-pebble microstructures and stable skeletons for enhanced ion transmembrane transport.By mixing artificial river water and seawater,the composite membrane achieved a high output power density up to 5.26 W m^(−2).Additionally,the membrane had an excellent acid resistance,which enabled long-term use with over 67 W m^(−2) of power density.The performance of this composite membrane benefited from the mechanically strong cellulose fibers and the bonding between nanofibers and nanolamellas.In this work,we highlight promising directions in industrial waste treatment using energy extracted from chemical potential gradients.
基金supported by the start-up funding from Xi'an Jiaotong University,the Fundamental Research Funds for the Central Universities(2015qngzl2)the China National Funds for Excellent Young Scientists(21522106)the National Natural Science Foundation of China(21371140)
文摘We reported a facile and robust one-pot wet chemistry strategy to achieve the growth of uniform three dimensional（3D） MoSe_2 ultrathin nanostructures on graphene nanosheets to form high quality MoSe_2/rGO hybrid nanostructures.Owing to the graphene as a support,it can significantly prevent the aggregation of MoSe_2 and the distribution of MoSe_2 on graphene was highly uniform.Importantly,due to the unique structures,the as-harvested MoSe_2/rGO hybrid exhibited excellent electrochemical performance as anode materials for sodium-ion battery（SIB）.When evaluated in a half cell system,the MoSe_2/rGO hybrid nanostructures could deliver a capacity of 200.2 mA h g^（-1） at8 A g^（-1） and maintain a capacity of 230.1 mA h g^（-1） over 100 cycles at 5 A g^（-1）.When coupled with Na_3V_2（PO_4）_3 cathode in a full cell system,the material could deliver a discharge capacity of 363.1 mA h g^（-1） at the current density of 0.5 A g^（-1）.Moreover,a discharge capacity of 56.4 mA h g^（-1） could be achieved even at a high current density of 10 A g^（-1）,which clearly suggested the high power capability of MoSe_2/rGO hybrid nanostructures for sodium ion energy storage.
基金the National Natural Science Foundation of China(No.50730008)the National Basic Research Program(973)of China(No.2006CB300406)
文摘Powder metallurgy was used to fabricate carbon nanotube(CNT) field emission cathodes.CNTs and tin(Sn) powder were blended,compacted and sintered.After polishing and etching,CNTs were exposed and protruded from the metal surface.CNTs were embedded into the Sn matrix,which acted as stable field emitters. The J-E curves show excellent field emission properties,such as low turn-on field of 2.8 V/μm,high emission current density and good current stability.
