Engineered nitrogen doping on VO_(2)(B)enables fast and reversible zinc-ion storage capability for aqueous zinc-ion batteries

Vanadium-based compounds with high theoretical capacities and relatively stable crystal structures are potential cathodes for aqueous zinc-ion batteries(AZIBs).Nevertheless,their low electronic conductivity and sluggish zinc-ion diffusion kinetics in the crystal lattice are greatly obstructing their practical application.Herein,a general and simple nitrogen doping strategy is proposed to construct nitrogen-doped VO_(2)(B)nanobelts(denoted as VO_(2)-N)by the ammonia heat treatment.Compared with pure VO_(2)(B),VO_(2)-N shows an expanded lattice,reduced grain size,and disordered structure,which facilitates ion transport,provides additional ion storage sites,and improves structural durability,thus presenting much-enhanced zinc-ion storage performance.Density functional theory calculations demonstrate that nitrogen doping in VO_(2)(B)improves its electronic properties and reduces the zinc-ion diffusion barrier.The optimal VO_(2)-N400 electrode exhibits a high specific capacity of 373.7 mA h g^(-1)after 100 cycles at 0.1 A g^(-1)and stable cycling performance after 2000 cycles at 5 A g^(-1).The zinc-ion storage mechanism of VO_(2)-N is identified as a typical intercalation/de-intercalation process.

Rare-Earth Metal Alkyl Complexes with 3-Arylamido-Functionalized Indolyl Ligands:Synthesis,Characterization and Reactivity

A series of dinuclear rare-earth metal alkyl complexes{[μ-η^2:η^1:η^1-3-(LNCH)(CH2SiMe3)Ind]RE-(CH2SiMe3)(THF)}2(L^1=2-tBuC6H4,RE=Y,Gd,Dy,Er,Yb;L^2=2,4,6-Me3C6H2,RE=Dy,Er;Ind=indolyl)and{[μ-η^2:η^1:η^1-3-(LNCH2)Ind]RE(CH2SiMe3)(THF)}2(L^1,RE=Y,Dy,Er,Yb;L^2,RE=Er,Yb)bearing 3-arylamido functionalized indolyl ligands having diverse bonding modes with metal ions were synthesized either by the insertion reaction of the imino group to the RE-C bond or by the alkane elimination reaction.In the preparation of above complexes,rare-earth metal alkyl complexes{[μ-η^5:η^1:η^1-3-(L^2 NCH)(CH2SiMe3)Ind]Gd(CH2SiMe3)(THF)}2 with aμ-η^5:η^1:η^1 coordination mode to the gadolinium ion and{[μ-η^3:η^1:η^1-3-(L^2NCH2)Ind]Dy(CH2SiMe3)(THF)}2 with aμ-η^3:η^1:η^1 coordination mode to the dysprosium ion were unexpectedly isolated.The reactions of 3-(L^2N=CH)lnd with Er(CH2SiMe3)3(THF)2 at room temperature,generated a tetranuclear imino-indolyl erbium intermediate{[μ-η^1:η^1-3-(L^2N=CH)Ind]Er(CH2SiMe3)2(THF)}4,which can transform into the amido functionalized indolyl erbium complex in hot toluene.Moreover,the reactivities of the newly synthesized ytterbium complex with N-heterocyclic compounds were investigated,affording the corresponding products of the mixed pyridyl-indolyl,imidazolyl-indolyl,and ortho-metalated complexes.The yttrium complexes showed a high regioselectivity and steroselectivity for the isoprene polymerization with 1,4-trans selectivity up to 91.7%and 1,4-cis selectivity up to 96.1%in the presence of cocatalysts,respectively.