Zinc is common metal used for steel protection from corrosion.The addition of further element,such as Ni,can modify the corrosion rate and maintain sacrificial protection.The anodic dissolution behavior of Zn,Ni and Z...Zinc is common metal used for steel protection from corrosion.The addition of further element,such as Ni,can modify the corrosion rate and maintain sacrificial protection.The anodic dissolution behavior of Zn,Ni and Zn-Ni alloys with different Ni contents（from 0.5% to 10%,mass fraction） in 3.5% Na Cl solution was investigated using potentiodynamic,potentiostatic and galvanostatic techniques.The composition and microstructure of the corrosion layer on Zn,Ni and Zn-Ni alloys were characterized by energy-dispersive X-ray spectroscopy analysis（EDX） and scanning electron microscopy（SEM）.The galvanostatic curves show that the anodic behavior of all investigated electrodes exhibits active/passive transition and the tendency of the alloys to passivity decreases with the increase in Ni content,except for 99.5Zn-0.5Ni alloy.While the potentiodynamic curves exhibit active passive transition only for pure Zn.Surface analysis reveals the presence of oxides,chlorides and metal hydroxide chloride in corrosion products,and very small cracks are observed for 90Zn-10 Ni alloy compared with that of Zn.展开更多
Understanding the carbon-tolerant mechanisms from a microscopic view is of special importance to develop proper anodes for solid oxide fuel cells.In this work,we employed density-functional theory calculations to stud...Understanding the carbon-tolerant mechanisms from a microscopic view is of special importance to develop proper anodes for solid oxide fuel cells.In this work,we employed density-functional theory calculations to study the CH4 reaction mechanism over a Ni/TiO2 nanostructure,which experimentally demonstrated good carbon tolerance.Six potential pathways for methane reforming reactions were studied over the Ni/TiO2(110)surface under both dry and wet atmospheres,and the main concerns were focused on the impact of TiO2 and Ni/TiO2 interface on CO/H2 formation.Our calculations suggest that the reaction between carbon and the interfacial lattice oxygen to form CO*is the dominant pathway for CH4 reforming under both dry and wet atmospheres,and intervention of steam directly to oxidize C*with its dissociated OH*group is less favorable in energy than that to wipe off oxygen vacancy to get ready for next C*oxidation.In all investigated paths,desorption of CO*is one of the most difficult steps.Fortunately,CO*desorption can be greatly promoted by the large heat released from the previous CO*formation process under wet atmosphere.H2O adsorption and dissociation over the TiO2 surface are found to be much easier than those over Ni,yttria stabilized zirconia(YSZ)and CeO2,which should be the key reason for the greatly depressed carbon deposition over Ni-TiO2 particles than traditional YSZ-Ni and CeO2-Ni anode.Our study presents the detailed CO*formation mechanism in CH4 reforming process over the Ni/TiO2 surface,which will benefit future research for exploring new carbon-tolerant solid oxide fuel cell anodes.展开更多
文摘Zinc is common metal used for steel protection from corrosion.The addition of further element,such as Ni,can modify the corrosion rate and maintain sacrificial protection.The anodic dissolution behavior of Zn,Ni and Zn-Ni alloys with different Ni contents（from 0.5% to 10%,mass fraction） in 3.5% Na Cl solution was investigated using potentiodynamic,potentiostatic and galvanostatic techniques.The composition and microstructure of the corrosion layer on Zn,Ni and Zn-Ni alloys were characterized by energy-dispersive X-ray spectroscopy analysis（EDX） and scanning electron microscopy（SEM）.The galvanostatic curves show that the anodic behavior of all investigated electrodes exhibits active/passive transition and the tendency of the alloys to passivity decreases with the increase in Ni content,except for 99.5Zn-0.5Ni alloy.While the potentiodynamic curves exhibit active passive transition only for pure Zn.Surface analysis reveals the presence of oxides,chlorides and metal hydroxide chloride in corrosion products,and very small cracks are observed for 90Zn-10 Ni alloy compared with that of Zn.
基金financially supported by the National Basic Research Program of China (2017YFA0402800 and 2016YFA0200602)the National Natural Science Foundation of China (51472228 and 21573204)+1 种基金the Fundamental Research Funds for the Central Universities (WK3430000004)the One Hundred Person Project of CAS
文摘Understanding the carbon-tolerant mechanisms from a microscopic view is of special importance to develop proper anodes for solid oxide fuel cells.In this work,we employed density-functional theory calculations to study the CH4 reaction mechanism over a Ni/TiO2 nanostructure,which experimentally demonstrated good carbon tolerance.Six potential pathways for methane reforming reactions were studied over the Ni/TiO2(110)surface under both dry and wet atmospheres,and the main concerns were focused on the impact of TiO2 and Ni/TiO2 interface on CO/H2 formation.Our calculations suggest that the reaction between carbon and the interfacial lattice oxygen to form CO*is the dominant pathway for CH4 reforming under both dry and wet atmospheres,and intervention of steam directly to oxidize C*with its dissociated OH*group is less favorable in energy than that to wipe off oxygen vacancy to get ready for next C*oxidation.In all investigated paths,desorption of CO*is one of the most difficult steps.Fortunately,CO*desorption can be greatly promoted by the large heat released from the previous CO*formation process under wet atmosphere.H2O adsorption and dissociation over the TiO2 surface are found to be much easier than those over Ni,yttria stabilized zirconia(YSZ)and CeO2,which should be the key reason for the greatly depressed carbon deposition over Ni-TiO2 particles than traditional YSZ-Ni and CeO2-Ni anode.Our study presents the detailed CO*formation mechanism in CH4 reforming process over the Ni/TiO2 surface,which will benefit future research for exploring new carbon-tolerant solid oxide fuel cell anodes.
