| The development of a feasible and inexpensive strategy to obtain and utilize sustainable energy is an important issue for the sustainable development of human society.Recently,Two-dimensional layered materials(graphene of nanoscale-carbon dots(CDs),molybdenum disulfide(MoS2))have attracted much attention owing to their unique optical properties and a wide range of applications.During the past few years,a tremendous amount of experimental studies has focused on the interesting optical properties of CDs and their promising applications in lightemitting diodes(LEDs),solar cells,sensing,bioimaging,and photocatalysis.Typical CDs reported so far consist of sp2 hybrid carbon cores and O-and N-containing functional groups distributed on their whole surface,leading to a stable aqueous dispersion.However,the controlled fabrication of lowcost optoelectronic devices is benefited from solution-processing technology in organic media.Obviously,water-soluble CDs cannot meet the requirements of solution-processing of LEDs and other photoelectronic devices.In addition,since graphene was discovered,ultrathin nanosheets of molybdenum disulfide(MoS2)have currently gained widespread interest because of their unique twodimensional(2D)layered structure as well as superior physical and chemical propertie.Very recently,MoS2 nanosheets in a metastable form of metallic 1T have also drawn attention because of their excellent properties in photoluminescence,electrocatalysts,photo-catalysts,and energy storage devices.It is very important to find an approach be obtained 1 T phase MoS2.In our research,by using solvent engineering,we retional design and controlable fabricate a series of highly fluorescent oil-soluble carbon dots(carbon quantum dots and graphene quantum dots).And we further applied the concepts of solvent engineering to the preparation of another kind of two-dimensional layered materials,1T-MoS2.The contents of this paper are as follows:1)The fabrication and control of CQDs with organic solubility and long-wavelength emission are still urgent issues to be addressed for their practical use in LEDs.Here,organic-soluble CQDs were produced at a high yield of～90%by a facile solvent engineering treatment of 1,3,6-trinitropyrene,which were simultaneously used as the nitrogen and carbon sources.The optical properties of the organic-soluble CQDs(o-CQDs)were investigated in nonpolar and polar solvents,films,and LED devices.The CQDs have a narrow size distribution around 2.66 nm,and can be dispersed in different organic solvents.Significantly,the as-prepared CQDs present an excitation-independent emission at 607 nm with fluorescence quantum yields(QYs)up to 65.93%in toluene solution.Furthermore,benefiting from the unique oilsolution properties,the as-prepared CQDs can be processed in thin film and device forms to meet the requirements of various applications,such as phosphor-based white-light LEDs.2)A rational strategy for scalable production of highly fluorescent CQDs in high yields(50-92%)based on controlled molecule fusion of activated polycyclic aromatic hydrocarbon in environmentally friendly polar solvents.By simply varying the composition of reaction solvents,their bandgaps were systematically manipulated,enabling the adjustment of fluorescent emissions from blue to red.Similar to conventional organic-soluble quantum dots but distinct from extensively reported water-soluble CQDs,the CQDs engineered in polar solvents are highly soluble in organic solvents and possess main features of intrinsic bandgap transitions,including overlapping of absorption and excitation spectra,excitation-independence fluorescence,the inversely proportional relationship of the bandgaps with fluorescence peak wavelength,and mono-exponential fluorescence decay.What’s more,the redfluorescent CQDs were encapsulated by liposomes,providing good biocompatibility and excellent in vitro and in vivo imaging capabilities.3)We introduced a facile solvent engineering route for well-crystallized GQDs with the existence of mesoporous silica nanoparticles(MSNs).The obtained GQDs were showed remarkable optical properties in solution,films,and LED devices.Significantly,these GQDs present an excitation-independent emission at 540 nm with an absolution fluorescence quantum yield(QY)up to 29.23%.4)We have developed a controllable solvothermal method to grow intrinsically conductive MoS2 nanosheet arrays in a metastable 1T phase on carbon fiber cloth(CFC)as binder-free,high-activity Li-ion battery(LIB)anodes.By introducing surface hydroxyl groups on the CFC and tuning the DMF content in the mixed solvent,MoS2 nanosheet arrays were perpendicularly grown to the surface of the carbon fibers with a high coverage.Electrochemical measurements reveal that the 1T phase nanosheet arrays have excellent Li-ion storage performances,including high specific capacity,high rate capability and good cycling stability,outperforming 2H phase arrays.Because of the metallic 1T phase and the highly oriented array architecture,after subtracting the total capacity of CFC,the 1T arrays also deliver a high reversible specific capacity of 1789 mAh g-1 at 0.1 Ag-1 and a retained capacity of 853 mAh g"1 after 140 cycles at 1 Ag-1. |
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