Two-step high-pressure high-temperature synthesis of nanodiamonds from naphthalene

Nanodiamonds have outstanding mechanical properties,chemical inertness,and biocompatibility,which give them potential in various applications.Current methods for preparing nanodiamonds often lead to products with impurities and uneven morphologies.We report a two-step high-pressure high-temperature(HPHT) method to synthesize nanodiamonds using naphthalene as the precursor without metal catalysts.The grain size of the diamonds decreases with increasing carbonization time(at constant pressure and temperature of 11.5 GPa and 700℃,respectively).This is discussed in terms of the different crystallinities of the carbon intermediates.The probability of secondary anvil cracking during the HPHT process is also reduced.These results indicate that the two-step method is efficient for synthesizing nanodiamonds,and that it is applicable to other organic precursors.

Deep-ultraviolet and visible dual-band photodetectors by integrating Chlorin e6 with Ga_(2)O_(3)

Gallium oxide(Ga_(2)O_(3))is a promising material for deep-ultraviolet(DUV)detection.In this work,Chlorin e6(Ce6)has been integrated with Ga_(2)O_(3)to achieve a DUV and visible dual-band photodetector,which can achieve multiple target information and improve the recognition rate.The photodetector shows two separate response bands at 268 nm and 456 nm.The DUV response band has a responsivity of 9.63 A/W with a full width at half maximum(FWHM)of 54.5 nm;the visible response band has a responsivity of 1.17 A/W with an FWHM of 45.3 nm.This work may provide a simple way to design and fabricate photodetectors with dual-band response.

Rational design multi-color-emissive chemiluminescent carbon nanodots in a single solvothermal reaction

Recently,the chemiluminescence(CL)induced by carbon nanodots(CDs)has intrigued researchers’extensive interests in various applications due to its special light emission principle.However,the difficulty of synthesizing chemiluminescent CDs with full-spectrum emission severely hinders the further regulation of the CL emission mechanism.Herein,the multi-color-emissive chemiluminescent CDs are rational designed and further synthesized by regulating the sp2-hybrid core and sp3-hybrid surface from the citrate-ammonia molecular in a single solvothermal reaction.More experimental characterizations and density functional theory calculations reveal that the higher temperature can promote the crosslinking polymerization/carbonization of carbon core and the higher protonation of solvent can determine the core size of final CDs,resulting in the variant CL emission from molecular-,crosslinking-and core-states.Thus,the CL emission of the CDs can be further synthesized by tuning the luminescence chromophores in the formation process via regulating the temperature and solvent,enabling the applications of the CL CDs in illumination and information encryption.This study paves a new technology to understand the luminescence of CDs and affords an industry translational potential over traditional chemiluminescent molecular.

Chemiluminescent carbon nanodots for dynamic and guided antibacteria

Advanced antibacterial technologies are needed to counter the rapid emergence of drug-resistant bacteria.Imageguided therapy is one of the most promising strategies for efficiently and accurately curing bacterial infections.Herein,a chemiluminescence(CL)-dynamic/guided antibacteria(CDGA)with multiple reactive oxygen species(ROS)generation capacity and chemiexcited near-infrared emission has been designed for the precise theranostics of bacterial infection by employing near-infrared emissive carbon nanodots(CDs)and peroxalate as CL fuels.Mechanistically,hydrogen peroxide generated in the bacterial microenvironment can trigger the chemically initiated electron exchange between CDs and energy-riched intermediate originated from the oxidized peroxalate,enabling bacterial induced inflammation imaging.Meanwhile,type Ⅰ/Ⅱ photochemical ROS production and type Ⅲ ultrafast charge transfer from CDs under the self-illumination can inhibit the bacteria proliferation efficiently.The potential clinical utility of CDGA is further demonstrated in bacteria infected mice trauma model.The self-illuminating CDGA exhibits an excellent in vivo imaging quality in early detecting wound infections and internal inflammation caused by bacteria,and further are proven as efficient broad-spectrum antibacterial nanomedicines without drug-resistance,whose sterilizing rate is up to 99.99%.

Self-exothermic reaction driven large-scale synthesis ofphosphorescent carbon nanodots

Phosphorescent carbon nanodots(CNDs)have various attractive properties and potential applications,but it remains a formidable challenge to achieve large-scale phosphorescent CNDs limited by current methods.Herein,a large-scale synthesis method for phosphorescent CNDs has been demonstrated via precursors’self-exothermic reaction at room temperature.The as-prepared CNDs show fluorescence and phosphorescence property,which are comparable with that synthesized by solvothermal and microwave method.Experimental and computational studies indicate that exotic atom doped sp^(2) hybridized carbon core works as an emissive center,which facilities the intersystem crossing from singlet state to triplet state.The CNDs show phosphorescence with tunable lifetimes from 193 ms to 1.13 s at different temperatures.The demonstration of large-scale synthesis of phosphorescent CNDs at room temperature opens up a new window for room temperature fabrication phosphorescent CNDs.

Micro-structured lepidocrocite-type H_(1.07)Ti_(1.73)O_(4)as anode for lithium-ion batteries with an ultrahigh rate and long-term cycling performance

The lepidocrocite-type H_(1.07)Ti_(1.73)O_(4) microsized structures with a tap density of 0.88 g·cm^(-3) were prepared through the ion exchange method with K_(0.8)Li_(0.27)Ti_(1.73)O_(4) powder as the precursor,and they exhibited good rate performance and outstanding cycle stability as an anode material for lithium ion batteries(LIB).The ion exchange method provides favorable conditions for H_(1.07)Ti_(1.73)O_(4) as an anode electrode material for LIBs.X-ray photoelectron spectroscopy(XPS)result demonstrates the existence of defects in the nonstoichiometric H1.07Ti1.73O4,which have a beneficial effect on the LIB performance.The electrochemical performance test proves that the half-cell with microsized H_(1.07)Ti_(1.73)O_(4)as the anode electrode can maintain a specific capacity of 129.5 mAh·g^(-1) after 1100 cycles and 101 mAh·g^(-1)after 3000 long cycles at high current densities of 2.0 and 5.0 A·g^(-1),respectively.In addition,the small volume change rate of 3.6%in H_(1.07)Ti_(1.73)O_(4)during Li ion insertion was confirmed by real-time in situ transmission electron microscopy(TEM).The LiFePO_(4)||H_(1.07)Ti_(1.73)O_(4)full battery exhibits a longterm cycling stability with a specific capacity of73.8 mAh·g^(-1) at a current density of 500 mA·g^(-1) after 200 cycles.

Ultraviolet phosphorescent carbon nanodots

Phosphorescent carbon nanodots(CNDs)have generated enormous interest recently,and the CND phosphorescence is usually located in the visible region,while ultraviolet(UV)phosphorescent CNDs have not been reported thus far.Herein,the UV phosphorescence of CNDs was achieved by decreasing conjugation size and in-situ spatial confinement in a NaCNO crystal.The electron transition from the P_(x) to the sp^(2) orbit of the N atoms within the CNDs can generate one-unit orbital angular momentum,providing a driving force for the triplet excitons population of the CNDs.The confinement caused by the NaCNO crystal reduces the energy dissipation paths of the generated triplet excitons.By further tailoring the size of the CNDs,the phosphorescence wavelength can be tuned to 348 nm,and the room temperature lifetime of the CNDs can reach 15.8 ms.As a demonstration,the UV phosphorescent CNDs were used for inactivating gram-negative and gram-positive bacteria through the emission of their high-energy photons over a long duration,and the resulting antibacterial efficiency reached over 99.9%.This work provides a rational design strategy for UV phosphorescent CNDs and demonstrates their novel antibacterial applications.