Microwave-Assisted Confining Growth and Liquid Exfoliation of sp^(3)-Hybrid Carbon Nitride Nano/Micro-Crystals

As one promising carbon-based material,sp^(3)-hybrid carbon nitride has been predicted with various novel physicochemical properties.However,the synthesis of sp^(3)-hybrid carbon nitride is still limited by the nanaoscale,low crystallinity,complex source,and expensive instruments.Herein,we have presented a facile approach to the sp^(3)-hybrid carbon nitride nano/micro-crystals with microwave-assisted confining growth and liquid exfoliation.Actually,the carbon nitride nano/micro-crystals can spontaneously emerge and grow in the microwave-assisted polymerization of citric acid and urea,and the liquid exfoliation can break the bulk disorder polymer to retrieve the highly crystalline carbon nitride nano/micro-crystals.The obtained carbon nitride nano/micro-crystals present superior blue light absorption strength and surprising photoluminescence quantum yields of 57.96% in ethanol and 18.05%in solid state.The experimental characterizations and density functional theory calculations reveal that the interface-trapped localized exciton may contribute to the excellent intrinsic light emission capability of carbon nitride nano/micro-crystals and the interparticle staggered stacking will prevent the aggregation-caused-quenching partially.Finally,the carbon nitride nano/micro-crystals are demonstrated to be potentially useful as the phosphor medium in light-emitting-diode for interrupting blue light-induced eye damage.This work paves new light on the synthesis strategy of sp^(3)-hybrid carbon nitride materials and thus may push forward the development of multiple carbon nitride research.

Computational Prediction of a Novel Superhard sp^(3) Trigonal Carbon Allotrope with Bandgap Larger than Diamond

Searching for new carbon allotropes with superior properties has been a longstanding interest in material sciences and condensed matter physics.Here we identify a novel superhard carbon phase with an 18-atom trigonal unit cell in a full-sp^(3) bonding network,termed tri-C_(18) carbon,by first-principles calculations.Its structural stability has been verified by total energy,phonon spectra,elastic constants,and molecular dynamics simulations.Furthermore,tri-C_(18) carbon has a high bulk modulus of 400 GPa and Vickers hardness of 79.0 GPa,comparable to those of diamond.Meanwhile,the simulated x-ray diffraction pattern of tri-C_(18) carbon matches well with the previously unexplained diffraction peaks found in chimney soot,indicating the possible presence of tri-C_(18) carbon.Remarkably,electronic band structure calculations reveal that tri-C_(18) carbon has a wide indirect bandgap of 6.32 eV,larger than that of cubic diamond,indicating its great potential in electronic or optoelectronic devices working in the deep ultraviolet region.

Sensitive humidity sensor based on moisture-driven energy generation

The emergence of novel self-powered humidity sensors has attracted considerable attention in the fields of smart electronic devices and personal healthcare.Herein,self-powered humidity sensors have been fabricated using a moisture-driven energy generation(MEG)device based on asymmetric tubular graphitic carbon nitride(g-CN)films prepared on anodized aluminum(AAO)template.At a relative humidity(RH)of 96%,the MEG device can provide an open-circuit voltage of 0.47 V and a short-circuit current of 3.51μA,with a maximum output power of 0.08μW.With inherent self-powered ability and humidity response via current variation,an extraordinary response of 1.78×106%(41%-96%RH)can be gained from the MEG device.The possible power generation mechanism is that g-CN/AAO heterostructure can form ion gradient and diffusion under the action of moisture to convert chemical potential into electrical potential,evoking a connaturally sensitive response to humidity.Self-powered respiration monitoring device based on the sensor is designed to monitor human movement(sitting,warming up,and running)and sleep status(normal,snoring,and apnea),maintaining excellent stability during cumulative 12-h respiration monitoring.This self-powered humidity sensing technology has promising potential for extensive integration into smart electronic and round-the-clock health monitoring devices.

Three-dimensional Ag/carbon nanotube-graphene foam for high performance dendrite free lithium/sodium metal anodes

Although lithium metal and sodium metal are promised as ideal anodes for lithium ion batteries(LIBs)and sodium ion batteries(SIBs),they still suffer from inevitable dendrite growth.In light of this,silver nanoparticles(Ag NPs)are sputtered onto three-dimensional carbon nanotube decorated graphene foam(3D CNT-GF)to construct superior 3D Ag/CNT-GF composite matrix for lithium metal anodes(LMAs)and sodium metal anodes(SMAs).With this design,lithiophilic/sodiophilic Ag NPs could provide favorable sites to guide Li/Na metal nucleation and growth,thus leading to low nucleation overpotentials,high Coulombic efficiency and long cycle performance.Accordingly,3D Ag/CNT-GF electrodes can stably cy-cle for 1000 and 750 cycles at 3 mA cm^(−2)with 1 mAh cm^(−2)for SMAs and LMAs,respectively.More attractively,it can also stably sustain 300 cycles(SMAs)and 500 cycles(LMAs)at a large current den-sity of 5 mA cm^(−2)with 1 mAh cm^(−2).The excellent electrochemical performance can be attributed to the lithiophilic/sodiophilic electrode surface,3D porous electrode structure and the dendrite-free mor-phology as demonstrated by ex-situ scanning electron microscopy(SEM)and in-situ optical microscopy analyses.Furthermore,full cells based on Na@3D Ag/CNT-GF||Na 3 V 2(PO 4)3@carbon(NVP@C)and Li@3D Ag/CNT-GF||LiFePO 4(LFP)could deliver highly reversible capacities of 90.1 and 106.4 mAh g^(−1),respec-tively,at 100 mA g^(−1)after 200 cycles for SIBs and LIBs,respectively.This work demonstrates a novel 3D Ag/CNT-GF matrix for boosting Li/Na deposition stability for their future applications.

Ga2O3 solar-blind position-sensitive detectors

Monoclinic Ga2O3(β-Ga2O3)is a promising material for achieving solar-blind photodetection because of its unique characteristics,including its high breakdown electric field,radiation hardness,thermal and chemical stabilities,and intrinsic visible/solar-blind properties.Until now,several studies have investigated the development of high-performanceβ-Ga2O3 solar-blind photodetectors.However,these photodetectors can only detect the light intensity but not the light position.In this work,fourquadrant position-sensitive detectors(4Q-PSDs)were developed and demonstrated based onβ-Ga2O3.4Q-PSDs,comprising four identical metal-semiconductor-metal-structured photodetector components,demonstrate high uniformity,large signal-tonoise ratio,good ultraviolet/visible rejection ratio,and fast response/recovery time.Subsequently,the position of the illumination beam can be determined by analyzing the output signals of the four photodetector components.This work may indicate the promising application potential of the Ga2O3-based photodetectors in the fields of positioning,aligning,and monitoring the solarblind beams.

Three-dimensional Au/carbon nanotube-graphene foam hybrid nanostructure for dendrite free sodium metal anode with long cycle stability

Sodium metal anode has been attracting widely research attention due to its large capacity and low electrode potential as the anode of sodium-ion batteries.However,the uncontrollable growth of Na dendrite is one of the critical issues for its real applications.Herein,a three-dimensional(3 D) nanostructure composed of gold nanoparticles(Au NPs) supported on 3 D carbon nanotube-graphene foam(3 D CNT-GF)was designed and fabricated as the host of sodium metal anode.Na@3 D Au/CNT-GF anode can deliver a Coulombic efficiency of 99.14% and stably cycle for 2600 h at 1 mA cm^(-2) with 1 mAh cm^(-2).It can cycle for 300 h at 5 mA cm^(-2) with 1 mAh cm^(-2).Detailed results indicate that its excellent electrochemical performance can be attributed to the unique macroporous structure and sodiophilic surface formed by Au NPs guiding the uniform sodium metal deposition enabled a dendrite-free morphology investigated by the ex-situ SEM and in-situ optical microscopy.At last,a full cell was assembled with Na@3 D Au/CNT-GF as the anode and Na_(3) V_(2)(PO_(4))_(3)@C as the cathode.It can deliver a capacity of 84.6 mAh g^(-1) at 100 mA g^(-1)after 200 cycles.Our results demonstrate that 3 D Au/CNT-GF is a promising sodium metal anode host.

Near-infrared chemiluminescent carbon nanogels for oncology imaging and therapy

Carbon nanogels(CNGs)with dual ability of reactive oxygen species(ROS)imaging and photodynamic therapy have been designed with selfassembled chemiluminescent carbonized polymer dots(CPDs).With efficient deep-red/near-infrared chemiluminescence(CL)emission and distinctive photodynamic capacity,the H2O2-driven chemiluminescent CNGs are further designed by assembling the polymeric conjugate and CL donors,enabling an in vitro and in vivo ROS bioimaging capability in animal inflammation models and a high-performance therapy for xenograft tumors.Mechanistically,ROS generated in inflammatory sites or tumor microenvironment can trigger the chemically initiated electron exchange luminescence in the chemical reaction of peroxalate and H2O2,enabling in vivo CL imaging.Meanwhile,part of the excited-state electrons will transfer to the ambient H2O or dissolved oxygen and in turn lead to the type I and type II photochemical ROS production of hydroxyl radicals or singlet oxygen,endowing the apoptosis of tumor cells and thus enabling cancer therapy.These results open up a new avenue for the design of multifunctional nanomaterials for bioimaging and antienoplastic agents.

Pressure-induced photoluminescence enhancement and ambient retention in confined carbon dots

Piezochromic luminescent materials have shown great potential in advanced optoelectronic applications.However,most of luminescent materials usually undergo emission quenching under external stimuli.Herein,we demonstrate for the first time that the photoluminescence of carbon dots(CDs)confined within sodium hydroxide can be enhanced when high pressure is applied.They exhibit a 1.6-fold fluorescence enhancement compared with pristine CDs.Importantly,the enhanced fluorescence intensity can be retained after the release of pressure to ambient conditions.A combination of experimental analysis and theoretical simulations indicates that such an enhanced emission is mainly attributed to the strong confinement resulting from the sodium hydroxide matrix,which can separate the CDs spatially and restrict the nonradiative pathway.These results provide a rational strategy for manipulating the optical properties of CDs with enhanced and retainable photoluminescence(PL)performance,thus opening up a venue for designing luminescent CDs-based materials.

Ultrasensitive monolayer-MoS_(2) heterojunction photodetectors realized via an asymmetric Fabry-Perot cavity

Two-dimensional(2D)materials have attracted significant attention as a promising candidate for electronic and optoelectronic devices.However,low absorption impairs the performance of few-layer 2D material-based photodetectors(PDs).Herein,we purpose an asymmetric Fabry-Perot cavity consisting of a dielectric layer and metallic film to enhance the interactions between light and monolayer molybdenum disulfide(MoS_(2)).The external quantum efficiency of the monolayer MoS_(2)heterojunction PD is enhanced by more than two orders of magnitude via optimizing the thickness of the dielectric layer.The monolayer-MoS_(2)/nickel oxide heterojunction PD exhibits a large on/off ratio of 2×10^(5),a responsivity of 703 A W^(-1),and an ultrahigh detectivity of 1.31×10^(15)Jones.The detectivity is the best value ever reported for monolayer-MoS_(2)heterojunction PDs.Our results may pave the way for high-performance 2D materialbased PDs.