Carbon nanotube-hyperbranched polymer core-shell nanowires with highly accessible redox-active sites for fast-charge organic lithium batteries

Organic electrode materials are promising for lithium-ion batteries(LIBs) because of their environmental friendliness and structural diversity.However,they always suffer from limited capacity,poor cycling stability,and rate performance.Herein,hexaazatrinaphthalene-based azo-linked hyperbranched polymer(HAHP) is designed and synthesized as a cathode for LIBs.However,the densely stacked morphology lowers the chance of the active sites participating in the redox reaction.To address this issue,the singlewalled carbon nanotube(SWCNT) template is used to induce the growth of nanosized HAHP on the surface of SWCNTs.The HAHP@SWCNT nanocomposites have porous structures and highly accessible active sites.Moreover,the strong π-π interaction between HAHP and highly conductive SWCNTs effectively endows the HAHP@SWCNT nanocomposites with improved cycling stability and fast charge-discharge rates.As a result,the HAHP@SWCNT nanocomposite cathode shows a high specific capacity(320.4 mA h g^(-1)at 100 mA g^(-1)),excellent cycling stability(800 cycles;290 mA h g^(-1)at 100 mA g^(-1),capacity retained 91%) and outstanding rate performance(235 mA h g^(-1)at 2000 mA g^(-1),76% capacity retention versus 50 mA g^(-1)).This work provides a strategy to combine the macromolecular structural design and micromorphology control of electrode materials for obtaining organic polymer cathodes for high-performance LIBs.

Solvent-controlled synthesis strategy of multicolor emission carbon dots and its applications in sensing and light-emitting devices

Carbon dots(CDs),as a new kind of carbon-based luminescent nanomaterials,have drawn widespread attention in the fields of fluorescence sensing,optoelectronic devices,and biological imaging.This work uses citric acid(CA)and Nile Blue A(NBA)as precursors.By simply changing the solvent in the reaction,their bandgaps were systematically controlled,thereby successfully obtaining bright blue,yellow and red fluorescence emission CDs(B-,Y-and RCDs).The higher quantum yield(QY)of B-,Y-and RCDs are 64%,57%and 51%,respectively.The selected precursors and different solvents are the key to the formation of three emission CDs.Detailed characterization and density functional theory(DFT)calculations further indicate that the difference in emission color of CDs is due to the size of the sp^(2) conjugate domain.In addition,we used multicolor CDs as fluorescent probes to investigate their performance in detection.Among them,BCDs and YCDs can detect Sudan Red I with high selectivity and sensitivity.In the concentration range of 0 to 80 pM,the detection limits are 56 and 41 nM,respectively.Multicolor emitting phosphors and fluorescent films are also obtained by mixing CDs with other matrices.Using Ultraviolet(UV)chip as the excitation source and combining with multicolor fluorescent film and a certain proportion of B-,Y-,and RCDs/epoxy resin composites,bright monochromatic light-emitting diodes(LEDs)and white LED(WLED)with high color rendering index(CRI)were prepared.The above results indicate that the multicolor CDs prepared by us have great application potential in the fields of food safety control and optical devices.

SbPS_(4):A novel anode for high-performance sodium-ion batteries

With the in-depth research of sodium-ion batteries(SIBs),the development of novel sodium-ion anode material has become a top priority.In this work,tube cluster-shaped SbPS_(4)was synthesized by a high-temperature solid phase reaction.Then the typical short tubular ternary thiophosphate SbPS_(4)compounded with graphene oxide(SbPS_(4)/GO)was successfully synthesized after ultrasonication and freeze-drying.SbPS_(4)shows a high theoretical specific capacity(1335 mAh/g)according to the conversion-alloying dual mechanisms.The unique short tube inserted in the spongy graphene structure of SbPS_(4)/GO results in boosting the Na ions transport and alleviating the huge volume change in the charging and discharging processes,improving the sodium storage performance.Consequently,the tubular SbPS_(4)compounded with 10%GO provides an outstanding capacity of 359.58 mAh/g at 500 mA/g.The result indicates that SbPS_(4)/GO anode has a promising application potential for SIBs.

Adsorption and desorption mechanisms on graphene oxide nanosheets: Kinetics and tuning

A knowledge of the adsorption and desorption behavior of sorbates on surface adsorptive site(SAS)is the key to optimizing the chemical reactivity of catalysts.However,direct identification of the chemical reactivity of SASs is still a challenge due to the limitations of characterization techniques.Here,we present a new pathway to determine the kinetics of adsorption/desorption on SASs of graphene oxide(GO)based on total internal reflectance fluorescence microscopy.The switching on and off of the fluorescent signal of SAS lit by carbon dots(CDs)was used to trace the adsorption process and desorption process.We find that sodium pyrophosphate(PPi)could increase the adsorption equilibrium of CDs thermodynamically and promote the substrate-assisted desorption pathway kinetically.At the single turnover level,it was disclosed that the species that can promote desorption may also be an adsorption promoter.Such discovery provides significant guidance for improving the chemical reactivity of the heterogeneous catalyst.

全固态离子选择性电极在可穿戴电化学传感器中的进展

人体汗液富含丰富的与身体健康状况相关的电解质,采用可穿戴电化学离子传感器对汗液实时监测可为身体健康提供合理的指导.基于全固态离子选择性电极的可穿戴电化学传感器因能够实时无创地分析生物体液离子受到越来越多的关注.开发新的固接层材料,探索新的电位响应机理及在可穿戴设备上的应用促进了全固态离子选择性电极的发展.本文综述了全固态离子选择性电极的研究进展,包括传统的电位响应机理(氧化还原电容和双电层电容原理)和新型固接层材料(导电聚合物、碳和其他纳米材料)以及在可穿戴柔性传感器方面的应用.最后对全固态离子选择性电极存在的挑战和未来的前景做出了展望.