Two sandwich-type uranyl-containing polytungstates catalyze aerobic synthesis of benzimidazoles

Diversified synthetic strategies are extremely important for the structural diversity of uranium-containing polyoxometalates(U-POMs)and their functional expansion.Herein,two sandwich-type U-POMs were reported,which are Na_(5.6)K_(6.4)[(UO_(2))(H_(2)O)(TeW_9O_(33))]_(2)·21H_(2)O(UTeW_9)and Na_(8.9)K_(2.7)H_(1.19)[K_(0.79)(UO_(2))_(2.21)(PW_9O_(34))_(2)]·12H_(2)O(UPW_9)using in-situ strategy and lacunary precursor strategy,respectively.UTeW_9 shows a typical Keggin-typeopen or half-sandwich configuration.

Electronic and topological properties of kagome lattice LaV3Si2

Topological kagome lattice at the frontier of fundamental physics plays a key role in non-trivial topological quantum state.Here,we predict and investigate kagome lattice rare-earth vanadium-based quantum material LaV3Si2using density functional theory calculations.Both phonon spectrum and crystal transformation show stability of this material,which may be grown by experimental method.Dirac fermions,flat bands,and van Hove points as some basic features are presented in band structure and surface states.Further,symmetry-based compatibility relations support enforced semi-metal for occupied electron numbers with strong Berry curvature.Our results suggest that rare-earth vanadium-based RV3Si2can be treated as a new family kagome lattice.

Composition optimized trimetallic PtNiRu dendritic nanostructures as I versatile and active electrocatalysts for alcohol oxidation

Platinum-based nano crystals are the most effective electrocatalysts for accelerati ng the chemical tran sformatio ns on the anode in direct alcohol fuel cells. To facilitate practical applications and overcome the drawbacks of diverse alcohols, it is significant to develop electrocatalysts with high activities and a wide fuel flexibility. Here, we demonstrate a practicable solution method for fabricating composition tun able trimetallic PtNiRu den dritic nano structures (DNSs) which can serve as versatile and active catalysts for electrooxidatio n of a variety of liquid alcohols. A series of trimetallic DNSs with tun able Pt/Ni/Ru atomic ratios were successfully syn thesized by simply adjusti ng the feeding of precursors. Detailed electrochemical test indicates that, among other compositions, the Pt66Ni27Ru7 DNSs present much superior electroactivity in catalyzing electrooxidation of liquid alcohols in acidic mediums. Specifically, the mass activity and specific activity on the Pt66Ni27Ru7 DNSs, for electrooxidation of methanol, ethanol, and ethylene glycol, are 4.57 and 4.34 times, 3.55 and 3.42 times, and 2.37 and 2.28 times that of the commercial Pt black, respectively. X-ray photoelectron spectroscopy and CO stripping studies reveal the adsorption of CO on these PtNiRu DNSs is much weaker than on pure Pt. Meanwhile, the surface Ru sites can provide neighbouring -OH groups to facilitate the oxidati on and removal of the adsorbed in termediates (-CO) on the surface Pt sites, effectively improvi ng the CO tolera nee of the catalysts. The PtNiRu DNSs also show effectively boosted capacity for breaking the C-C bond in C2-alcohols, showing great potential for fuel-flexible fuel cell applications.

Microstructure Evolution of Extruded Mg-6Gd Alloy Under 175 ℃ and 150 MPa

The tensile creep behavior of extruded Mg-6 Gd alloy,having the tensile yield strength of～ 110 MPa at 175 ℃,has been investigated under 175 ℃ and 150 MPa. In this study, the extruded Mg-6 Gd sample exhibits the total tensile strain of ～10.5% after the creep time of 1100 h,and the fast plastic strain of ～4.6% at the beginning of the creep test. The microstructure result suggests that the dislocation deformation is the main deformation mode during creep, and the grains with orientation close to(0001) II ED disappear after creep. The creep process containing a low creep strain has no effective promotion for the precipitation compared with the aging process without strain. The origination of creep crack is related to the formation of precipitate-free zone during creep. The work offers an important implication to research the microstructure evolution under an applied stress in a weak aging response Mg alloy.