Comprehensive Summary Poly-NHC-based organometallic assemblies 3-PF6,3-SbF6 and 3-OTf were obtained and verified by NMR spectroscopy,ESI mass spectrometry and single-crystal X-ray diffraction analyses.Controllable structural interconversion was observed between the poly-NHC-based organometallic assemblies and their self-aggregated dimers in solution affected by concentration,solvent and metal ion.1H NMR spectra of assembly 3-PF6 in CD3CN at different concentrations demonstrated controllable structural interconversion,and 19F NMR spectrum of assembly 3-PF6 at high concentration further evidenced the presence of the free hexafluorophosphate anion and encapsulated hexafluorophosphate anion for its two sets of signals.In addition,single-crystal X-ray diffraction analysis provided clear evidence that in the solid state,two assemblies 3-PF6 were vertically stuck,forming a self-aggregated dimer with an encapsulated hexafluorophosphate anion.Investigating the reversible structural interconversion is beneficial for revealing the intrinsic nature on the atom level and paving the way to design the stimuli-responsive functional system.
To tackle undesirable shuttle reaction and sluggish reaction kinetics in lithium–sulfur(Li–S)batteries,we develop a porous and high-density oxygen-doped tantalum nitride nanostructure(nano-TaNO)as an efficient catalyst through delicate tailoring.Benefiting from well-defined interior and surface nanopore channels,the nano-TaNO favors abundant sulfur storage,easy electrolyte infiltration and good electrons/Li+transport.More importantly,high-density O dopant in nano-TaNO not only provides high conductivity,but also promotes polysulfide adsorption/conversion via Li–O chemical interactions and the generation of S3∗−radicals to activate additional evolution path from S8 to Li_(2)S.Consequently,the nano-TaNObased cathode exhibits excellent specific capacity and cyclability even under high sulfur loading condition.These interesting findings suggest the great potential of tantalum nitride and a high amount of anion doping engineering in manipulating intermediates and building high-performance Li−S rechargeable batteries.
Shuang YuYonggui ZhangShuo YangKuikui XiaoDong CaiHuagui NieZhi Yang
The lantern-shaped cage Pd_(2)L_(4)and tweezer-like PdL_(2)can be synthesized from the trans-and cis-isomer of an azobenzene-containing ligand,respectively,which were characterized by^(1)H,^(13)C,^(1)H-^(1)H COSY,DOSY NMR spectroscopies,high-resolution ESI-MS and density function theory(DFT)calculations.The interconversion of Pd_(2)L_(4)and PdL_(2)can be achieved via the cis-trans isomerization of the azobenzene unit on the ligand upon alternative irradiation of light 365 nm or 420 nm.
Pursuing appropriate photo-active Li-ion storage materials and understanding their basic energy storage/conversion principle are pretty crucial for the rapidly developing photoassisted Li-ion batteries(PA-LIBs).Copper oxide(CuO)is one of the most popular candidates in both LIBs and photocatalysis.While CuO based PA-LIBs have never been reported yet.Herein,one-dimensional(1D)CuO nanowire arrays in situ grown on a three-dimensional(3D)copper foam support were employed as dualfunctional photoanode for both‘solar-to-electricity’and‘electricity-to-chemical’energy conversion in the PA-LIBs.It is found that light energy can be indeed stored and converted into electrical energy through the assembled CuO based PA-LIBs.Without external power source,the photo conversion efficiency of CuO based photocell reaches about 0.34%.Impressively,at a high current density of 4000 m A g^(-1),photoassisted discharge and charge specific capacity of CuO based PA-LIBs respectively receive 64.01%and 60.35%enhancement compared with the net electric charging and discharging process.Mechanism investigation reveals that photogenerated charges from CuO promote the interconversion between Cu^(2+)and Cu^(+)during the discharging/charging process,thus forcing the lithium storage reaction more completely and increasing the specific capacity of the PA-LIBs.This work can provide a general principle for the development of other high-efficient semiconductor-based PA-LIBs.
Electrochemical energy storage and conversion toward sustainable carbon neutrality cycle is of great interest in today's society.In this perspective,we highlight the interconversion between carbon dioxide and formic acid by means of electrocatalytic CO_(2)reduction reaction(CO_(2)RR)and formic acid oxidation reaction(FAOR)as an effective way to achieve that goal.In line with the distinctive catalytic nature of Pd to reversibly drive both FAOR and CO_(2)RR,we first illustrate the intimate mechanistic relation between these two reversed reactions over Pd surfaces.Next,recent advances in developing Pd-based bifunctional catalysts and relevant optimization strategies are briefly summarized,including geometric structure engineering with preferential facet exposure,construction of crystallographic ordering intermetallic,electronic structure manipulation through metal or metalloid doping to fine tune the binding strength for active and poisoning intermediates.At the end,our viewpoints on the design principles at both microscopic and macroscopic scales are offered toward an efficient CO_(2)and HCOOH interconversion loop.