Abstract The polypyrrole（PPy）@NiCo hybrid nanotube arrays have been successfully fabricated as a high performance electrocatalyst for hydrogen evolution reaction （HER） in alkaline solution. The strong electronic i...Abstract The polypyrrole（PPy）@NiCo hybrid nanotube arrays have been successfully fabricated as a high performance electrocatalyst for hydrogen evolution reaction （HER） in alkaline solution. The strong electronic interactions between PPy and NiCo alloy are confirmed by X-ray photoelectron spectroscopy and Raman spectra. Because these interations can remarkably reduce the apparent activation energy （Ea） for HER and enhance the turnover frequency of catalysts, the electrocatalytic performance of PPy@NiCo hybrid nanotube arrays are significantly improved. The electrochemical tests show that the PPy@NiCo hybrid catalysts exhibit a low overpotential of-186 mV at 10.0 mA·cm^-2 and a small tafel slope of 88.6 mV·deg^-1 for HER in the alkaline solution. The PPy@NiCo hybrid nanotubes also exhibit high catalytic activity and high stability for HER.展开更多
For the study of magnetic field-assisted assembly behavior,one-dimensional(1D)NiCo alloy nanostructures were solvothermally obtained at 180℃under an in situ magnetic field(the magnetic field as applied during the che...For the study of magnetic field-assisted assembly behavior,one-dimensional(1D)NiCo alloy nanostructures were solvothermally obtained at 180℃under an in situ magnetic field(the magnetic field as applied during the chemical reduction)and ex situ field(after the chemical reduction was finished).Microscopic morphology and magnetic properties differences were investigated using scanning electronic microscope(SEM)and vibrating sample magnetometer(VSM)for these products.Magnetic measurement results show that 1D ordered microstructures under in situ magnetic field possess higher saturation magnetization Ms, remnant magnetization Mr,coercivity Hc and reduced magnetization Mr/Ms than 1D ordered microstructures under ex situ field,and the four magnetic parameters of the two ordered microstructures are much higher than those randomly distributed alloy particles prepared in the absence of external magnetic field.展开更多
Effectof the austenitizing temperature on the microstructure, strength, and toughness of23 NiCo alloy wasstudied . With increasing theaustenitizingtemperature,the reductionsin strength and hardness are probably caused...Effectof the austenitizing temperature on the microstructure, strength, and toughness of23 NiCo alloy wasstudied . With increasing theaustenitizingtemperature,the reductionsin strength and hardness are probably caused by the coarsening of M2 Ccarbides. The use of higheraustenitizingtemperatureresultedinimproved impacttoughness duetothe dissolutionof undissolved,( CrFeMo)23 C6 carbides. For austenitizingtemperaturesgreaterthan 950 ℃ resultedinthelossofimpacttoughness. Astheaustenitizingtemperatureisincreasedto1050 ℃impacttoughnesslevelsarereduced on an averageby53 J/cm2 .Examination ofthefrac turesurfaceofimpacttoughnessspecimens viascanningelectron microscopy ( SEM) revealedthataustenitizing at1050 ℃and aged at482℃wasintergranularfracture .It wassuggested thatthisgrain boundary embrittlement wastheresultofthe formation of cementite particlesduring aging.展开更多
文摘Abstract The polypyrrole（PPy）@NiCo hybrid nanotube arrays have been successfully fabricated as a high performance electrocatalyst for hydrogen evolution reaction （HER） in alkaline solution. The strong electronic interactions between PPy and NiCo alloy are confirmed by X-ray photoelectron spectroscopy and Raman spectra. Because these interations can remarkably reduce the apparent activation energy （Ea） for HER and enhance the turnover frequency of catalysts, the electrocatalytic performance of PPy@NiCo hybrid nanotube arrays are significantly improved. The electrochemical tests show that the PPy@NiCo hybrid catalysts exhibit a low overpotential of-186 mV at 10.0 mA·cm^-2 and a small tafel slope of 88.6 mV·deg^-1 for HER in the alkaline solution. The PPy@NiCo hybrid nanotubes also exhibit high catalytic activity and high stability for HER.
基金Project(50901074)supported by the National Natural Science Foundation of ChinaProject(20080430778)supported by ChinaPostdoctoral Science FoundationProject(2008jq1002)supported by Young Teacher Natural Science Fundation of Anhui Province,China
文摘For the study of magnetic field-assisted assembly behavior,one-dimensional(1D)NiCo alloy nanostructures were solvothermally obtained at 180℃under an in situ magnetic field(the magnetic field as applied during the chemical reduction)and ex situ field(after the chemical reduction was finished).Microscopic morphology and magnetic properties differences were investigated using scanning electronic microscope(SEM)and vibrating sample magnetometer(VSM)for these products.Magnetic measurement results show that 1D ordered microstructures under in situ magnetic field possess higher saturation magnetization Ms, remnant magnetization Mr,coercivity Hc and reduced magnetization Mr/Ms than 1D ordered microstructures under ex situ field,and the four magnetic parameters of the two ordered microstructures are much higher than those randomly distributed alloy particles prepared in the absence of external magnetic field.
文摘Effectof the austenitizing temperature on the microstructure, strength, and toughness of23 NiCo alloy wasstudied . With increasing theaustenitizingtemperature,the reductionsin strength and hardness are probably caused by the coarsening of M2 Ccarbides. The use of higheraustenitizingtemperatureresultedinimproved impacttoughness duetothe dissolutionof undissolved,( CrFeMo)23 C6 carbides. For austenitizingtemperaturesgreaterthan 950 ℃ resultedinthelossofimpacttoughness. Astheaustenitizingtemperatureisincreasedto1050 ℃impacttoughnesslevelsarereduced on an averageby53 J/cm2 .Examination ofthefrac turesurfaceofimpacttoughnessspecimens viascanningelectron microscopy ( SEM) revealedthataustenitizing at1050 ℃and aged at482℃wasintergranularfracture .It wassuggested thatthisgrain boundary embrittlement wastheresultofthe formation of cementite particlesduring aging.
