Fabrication and properties of silver-based composites reinforced with carbon-coated Ti_(3)AlC_(2)

Ti_(3)AlC_(2)-reinforced Ag-based composites,which are used as sliding current collectors,electrical contacts,and electrode materials,exhibit remarkable performances.However,the interfacial reactions between Ag and Ti_(3)AlC_(2) significantly degrade the electrical and thermal properties of these composites.To diminish these interfacial reactions,we fabricated carbon-coated Ti_(3)AlC_(2) particles(C@Ti_(3)AlC_(2))as reinforcement and prepared Ag–10wt%C@Ti_(3)AlC_(2) composites with carbon-layer thicknesses ranging from 50–200 nm.Compared with the uncoated Ag–Ti_(3)AlC_(2) composite,Ag–C@Ti_(3)AlC_(2) was found to have a better distribution of Ti_(3)AlC_(2) particles.With increases in the carbon-layer thickness,the Vickers hardness value and relative density of Ag–C@Ti_(3)AlC_(2) gradually decreases.With a carbon-layer thickness of 150 nm,we obtained the lowest resistivity of Ag–C@Ti_(3)AlC_(2) of 29.4135.5×10^(−9)Ω·m,which is half that of Ag–Ti_(3)AlC_(2)(66.7×10^(−9)Ω·m).The thermal conductivity of Ag–C@Ti_(3)AlC_(2) reached a maximum value of 135.5 W·m^(−1)·K^(−1) with a 200-nm carbon coating(~1.8 times that of Ag–Ti_(3)AlC_(2)).These results indicate that the carbon-coating method is a feasible strategy for improving the performance of Ag–C@Ti_(3)AlC_(2) composites.

A New Many-Body Expansion Scheme for Atomic Clusters:Application to Nitrogen Clusters

Although the many-body expansion(MBE)approach is widely applied to estimate the energy of large systems containing weak interactions,it is inapplicable to calculating the energies of covalent or metal clusters.In this work,we propose an interaction manybody expansion(IMBE)to calculate the energy of atomic clusters containing covalent bonds.In this approach,the energy of a system is expressed as the sum of the energy of atoms and the interaction energy between the atom and its surrounding atoms.The IMBE method is first applied to calculate the energies of nitrogen clusters,in which the interatomic interactions are truncated to four-body terms.The results show that the IMBE approach could significantly reduce the energy error for nitrogen clusters compared with the traditional MBE method.The weak size and structure dependence of the IMBE error with respect to DFT calculations indicates the IMBE method has good potential application in estimating energy of large covalent systems.

Controllable synthesis and tunable photocatalytic activity of TiO2 nanowires via alcohol-thermal method

Titania nanowires(TiO2-NW)with tunable aspect ratios and morphologies were directly synthesized using a simple alcohol-thermal technique.Specifically,ethanol and acetic acid were used as solvents and lithium ion was used as the capping agent to promote the conversion of titanium butoxide into TiO2-NW.The morphologies and crystal phases of TiO2-NW were determined by the molar ratio of solvents and the content(mol%)of lithium ion.The band gap of TiO2-NW with pure anatase phase is slightly bigger than that of TiO2-NW with a mixture of anatase and rutile phases.All TiO2-NW could achieve effective decolorization of methyl blue(the decolorization rate is over 95%)after 35-min ultraviolet(UV)irradiation.

Editorial for rare metals, special issue on photocatalysis

Burning of fuels is an irreversible entropy increasing process,requiring additional energies derived from the environment to let the process cycle.In theory,photon energy delivered from the sun could fix the huge energy demand in a clean and sustainable way.Photocatalysis is such an ideal approach to reconvert inert molecules directly into fuels and other chemical feedstocks using photon energy without any other energy inputs.