The electrochemical behavior of metallic passive film on rebar in concrete is characterized by its semiconductive nature. The charge distribution at the interface between a semiconductor and an electrolyte is often de...The electrochemical behavior of metallic passive film on rebar in concrete is characterized by its semiconductive nature. The charge distribution at the interface between a semiconductor and an electrolyte is often determined by measuring the capacitance of the space-charge layer (Csc) as a function of the electrode potential (E). When the space charge-layer serves as the depletion layer, the relation of Csc^-2 vs E resembles a Mott-Schottky plot (M-S plot). The semiconductive properties of the passive film on rebar in concrete were analyzed with M-S plots to study the effect of chloride ions and mineral admixtures on rebar passive films. Some rebar electrodes were immersed in simulated concrete pore solutions, while others were embedded in concrete with/without mineral admixtures. In saturated Ca(OH), solutions, the relation of Csc^-2-E of rebar electrodes shows linear MottSchottky relationship indicating that the passive film on rebar is a highly disordered n-type semiconductor, with donor density (ND) in the order of 10^26m^-3. After adding chloride ions (Cl wt%〈0.2%) in system solutions, the M-S plot slopes significantly decreased and ND increased, suggesting that chloride ion will cause passive film corrosion and breakdown. The M-S plots of the passive film on rebar electrodes embedded in concrete were similar to those immersed in simulated system solution. However, ND of those in concrete with mineral admixtures tended to be a little smaller, indicating that introducing proper quantity admixtures into concrete could make the rebar passive film have a thicker space-charge layer and therefore a thicker passive film layer.展开更多
Anodic aluminum oxide (AAO) with highly ordered nanoscale pores which are monodisperse and mutually parallel can be produced through a self-organized electrochemical process. Subsequent deposition of materials into ...Anodic aluminum oxide (AAO) with highly ordered nanoscale pores which are monodisperse and mutually parallel can be produced through a self-organized electrochemical process. Subsequent deposition of materials into the nanopores produces AA0 embedded nanowire arrays. Whilst the templates can be further removed to obtain free individual nanowires, the em- bedded nanowires form an interesting nanocomposite structure. Recent research activities on the fabrication and characteriza- tion of AAO template based magnetic nanowires are reviewed in this article. Studies of specific systems are given as an exam- ple of the research in the area.展开更多
Two-dimensional(2D)materials possess unique thickness-and lateral-size-dependent properties.Many efforts have been devoted to obtaining 2D materials with narrow structure heterogeneity while it is still challenging to...Two-dimensional(2D)materials possess unique thickness-and lateral-size-dependent properties.Many efforts have been devoted to obtaining 2D materials with narrow structure heterogeneity while it is still challenging to independently control their thickness and lateral size,limiting their widespread applications.Here,we develop a three-step method which achieves independent thickness and lateral size sorting of 2D materials.Taking 2D h-BN flakes as an example,their thickness and lateral size are independently sorted to different fractions with thicknesses smaller than 6 nm.In addition,the 2D h-BN flakes possess narrow distributions of both thickness and lateral size.We further develop a force field extraction method and achieve scalable size sorting of 2D h-BN,which is universal for sorting other 2D materials including MoS2 and graphene oxide.This work reports an effective method to produce structure homogenous 2D materials and will help fundamental studies and applications of 2D materials where thickness and lateral size are of concern.展开更多
基金Project (No. 502019) supported by the Natural Science Foundationof Zhejiang Province, China
文摘The electrochemical behavior of metallic passive film on rebar in concrete is characterized by its semiconductive nature. The charge distribution at the interface between a semiconductor and an electrolyte is often determined by measuring the capacitance of the space-charge layer (Csc) as a function of the electrode potential (E). When the space charge-layer serves as the depletion layer, the relation of Csc^-2 vs E resembles a Mott-Schottky plot (M-S plot). The semiconductive properties of the passive film on rebar in concrete were analyzed with M-S plots to study the effect of chloride ions and mineral admixtures on rebar passive films. Some rebar electrodes were immersed in simulated concrete pore solutions, while others were embedded in concrete with/without mineral admixtures. In saturated Ca(OH), solutions, the relation of Csc^-2-E of rebar electrodes shows linear MottSchottky relationship indicating that the passive film on rebar is a highly disordered n-type semiconductor, with donor density (ND) in the order of 10^26m^-3. After adding chloride ions (Cl wt%〈0.2%) in system solutions, the M-S plot slopes significantly decreased and ND increased, suggesting that chloride ion will cause passive film corrosion and breakdown. The M-S plots of the passive film on rebar electrodes embedded in concrete were similar to those immersed in simulated system solution. However, ND of those in concrete with mineral admixtures tended to be a little smaller, indicating that introducing proper quantity admixtures into concrete could make the rebar passive film have a thicker space-charge layer and therefore a thicker passive film layer.
文摘Anodic aluminum oxide (AAO) with highly ordered nanoscale pores which are monodisperse and mutually parallel can be produced through a self-organized electrochemical process. Subsequent deposition of materials into the nanopores produces AA0 embedded nanowire arrays. Whilst the templates can be further removed to obtain free individual nanowires, the em- bedded nanowires form an interesting nanocomposite structure. Recent research activities on the fabrication and characteriza- tion of AAO template based magnetic nanowires are reviewed in this article. Studies of specific systems are given as an exam- ple of the research in the area.
基金the National Natural Science Foundation of China(51920105002,51991340,and 51991343)Guangdong Innovative and Entrepreneurial Research Team Program(2017ZT07C341)+2 种基金the Bureau of Industry and Information Technology of Shenzhen for the“2017 Graphene Manufacturing Innovation Center Project”(201901171523)Shenzhen Basic Research Project(JCYJ20190809180605522,JCYJ20200109144620815 and JCYJ20200109144616617)China Postdoctoral Science Foundation(2020M680540)。
文摘Two-dimensional(2D)materials possess unique thickness-and lateral-size-dependent properties.Many efforts have been devoted to obtaining 2D materials with narrow structure heterogeneity while it is still challenging to independently control their thickness and lateral size,limiting their widespread applications.Here,we develop a three-step method which achieves independent thickness and lateral size sorting of 2D materials.Taking 2D h-BN flakes as an example,their thickness and lateral size are independently sorted to different fractions with thicknesses smaller than 6 nm.In addition,the 2D h-BN flakes possess narrow distributions of both thickness and lateral size.We further develop a force field extraction method and achieve scalable size sorting of 2D h-BN,which is universal for sorting other 2D materials including MoS2 and graphene oxide.This work reports an effective method to produce structure homogenous 2D materials and will help fundamental studies and applications of 2D materials where thickness and lateral size are of concern.