In this study,a novel lubricant additive nitrogen-doped carbon quantum dot(N-CQD)nanoparticle was prepared by the solvothermal method.The synthesized spherical N-CQD nanoparticles in the diameter of about 10 nm had a ...In this study,a novel lubricant additive nitrogen-doped carbon quantum dot(N-CQD)nanoparticle was prepared by the solvothermal method.The synthesized spherical N-CQD nanoparticles in the diameter of about 10 nm had a graphene oxide(GO)-like structure with various oxygen(O)-and nitrogen(N)-containing functional groups.Then N-CQDs were added to MoS_(2)nanofluid,and the tribological properties for steel/steel friction pairs were evaluated using a pin-on-disk tribometer.Non-equilibrium molecular dynamics(NEMD)simulations for the friction system with MoS_(2)or MoS_(2)+N-CQD nanoparticles were also conducted.The results showed that friction processes with MoS_(2)+N-CQD nanofluids were under the mixed lubrication regime.And MoS_(2)nanofluid containing 0.4 wt%N-CQDs could achieve 30.4%and 31.0%reduction in the friction coefficient and wear rate,respectively,compared to those without N-CQDs.By analyzing the worn surface topography and chemical compositions,the excellent lubrication performance resulted from the formation of tribochemistry-induced tribofilm.The average thickness of tribofilm was about 13.9 nm,and it was composed of amorphous substances,ultrafine crystalline nanoparticles,and self-lubricating FeSO_(4)/Fe2(SO_(4))_(3).NEMD simulation results indicated the interaction between S atoms in MoS_(2)as well as these O-and N-containing functional groups in N-CQDs with steel surfaces enhanced the stability and strength of tribofilm.Thereby the metal surface was further protected from friction and wear.展开更多
As prospective energy storage devices,zinc-ion hybrid capacitors(ZHCs)still suffer from unsatisfactory cathode materials.Herein,the three dimensional(3D)N,B dual-doped carbon quantum dots/reduced graphene oxide(N,B-CQ...As prospective energy storage devices,zinc-ion hybrid capacitors(ZHCs)still suffer from unsatisfactory cathode materials.Herein,the three dimensional(3D)N,B dual-doped carbon quantum dots/reduced graphene oxide(N,B-CQDs/rGO)composite aerogel is prepared via a onepot hydrothermal method.Thanks to the synergism of CQDs modification and N,B dual-doping,the resultant N,B-CQDs/rGO composite aerogel delivers superior electrochemical properties.Furthermore,the as-obtained N,B-CQDs/rGO composite aerogel is served as a cathode for aqueous and flexible quasi-solid-state ZHCs for the first time.Impressively,the aqueous N,B-CQDs/rGO//Zn ZHC manifests a large energy density of 96.2 Wh·kg^(-1)at80 W·kg^(-1)and still remains a high energy density of 54.7Wh·kg^(-1)at a superb power density of 80 kW·kg^(-1).Meanwhile,kinetic analyses are employed to elucidate the prominent power performance,and various ex situ tests are undertaken to explore the energy storage mechanism of aqueous ZHC.More notably,the flexible quasi-solid-state N,B-CQDs/rGO//Zn ZHC displays a desirable energy density(89.1μWh·cm^(-2)),a superior power density(96,000μW·cm^(-2))and exceptional flexible performance.The present study offers a valuable reference for designing and developing advanced cathode materials for aqueous and flexible quasi-solid-state ZHCs.展开更多
Colloidal quantum dots(CQDs)are of great interest to photovoltaic(PV)technologies as they possess the benefits of solution-processability,size-tunability,and roll-to-roll manufacturability,as well as unique capabiliti...Colloidal quantum dots(CQDs)are of great interest to photovoltaic(PV)technologies as they possess the benefits of solution-processability,size-tunability,and roll-to-roll manufacturability,as well as unique capabilities to harvest near-infrared(NIR)radiation.During the last decade,lab-scale CQD solar cells have achieved rapid improvement in the power conversion efficiency(PCE)from~1%to 18%,which will potentially exceed 20%in the next few years and approach the performance of other PV technologies,such as perovskite solar cells and organic solar cells.In the meanwhile,CQD solar cells exhibit long lifetimes either under shelf storage or continuous operation,making them highly attractive to industry.However,in order to meet the industrial requirements,mass production techniques are necessary to scale up the fabrication of those lab devices into large-area PV modules,such as roll-to-toll coating.This paper reviews the recent developments of large-area CQD solar cells with a focus on various fabrication methods and their principles.It covers the progress of typical large-area coating techniques,including spray coating,blade coating,dip coating,and slot-die coating.It also discusses next steps and new strategies to accomplish the ultimate goal of the low-cost large-area fabrication of CQD solar cells and emphasizes how artificial intelligence or machine learning could facilitate the developments of CQD solar cell research.展开更多
The carbon quantum dots(CQDs)and their functionalized materials are promising in biomedical field because of their unique properties;meanwhile,a growing concern has been raised about the potential toxicity of these mo...The carbon quantum dots(CQDs)and their functionalized materials are promising in biomedical field because of their unique properties;meanwhile,a growing concern has been raised about the potential toxicity of these modified materials in biosystem.In this study,we synthesized original CQDs and two common functionalized CQDs including N-doped CQDs(NCQDs)and folic acid-modified CQDs(FACQDs),and compared the toxicity and biocompatibility with each other in vitro and in vivo.L929,C6 and normal cell MDCK were selected to detect the adverse reaction of these materials in vitro.No acute toxicity or obvious changes were noted from in vitro cytotoxicity studies with the dose of these CQD materials increasing to a high concentration at 1 mg/mL.Among these materials,the FA-CQDs show a much lower toxicity.Moreover,in vivo toxicity studies were performed on the nude mice for 15 days.The experimental animals in 10 or 15 mg/kg groups were similar with animals treated by phosphate buffer solution(PBS)after 15 days.The results of the multifa rious biochemical parameters also suggest that the functionalized products of CQDs do not influence the biological indicators at feasible concentration.Our findings in vitro and in vivo through toxicity tests demonstrate that CQDs and their modified materials are safe for future biological applications.展开更多
基金This work was supported by the National Natural Science Foundation of China(No.51874036)Beijing Municipal Natural Science Foundation(No.2182041).
文摘In this study,a novel lubricant additive nitrogen-doped carbon quantum dot(N-CQD)nanoparticle was prepared by the solvothermal method.The synthesized spherical N-CQD nanoparticles in the diameter of about 10 nm had a graphene oxide(GO)-like structure with various oxygen(O)-and nitrogen(N)-containing functional groups.Then N-CQDs were added to MoS_(2)nanofluid,and the tribological properties for steel/steel friction pairs were evaluated using a pin-on-disk tribometer.Non-equilibrium molecular dynamics(NEMD)simulations for the friction system with MoS_(2)or MoS_(2)+N-CQD nanoparticles were also conducted.The results showed that friction processes with MoS_(2)+N-CQD nanofluids were under the mixed lubrication regime.And MoS_(2)nanofluid containing 0.4 wt%N-CQDs could achieve 30.4%and 31.0%reduction in the friction coefficient and wear rate,respectively,compared to those without N-CQDs.By analyzing the worn surface topography and chemical compositions,the excellent lubrication performance resulted from the formation of tribochemistry-induced tribofilm.The average thickness of tribofilm was about 13.9 nm,and it was composed of amorphous substances,ultrafine crystalline nanoparticles,and self-lubricating FeSO_(4)/Fe2(SO_(4))_(3).NEMD simulation results indicated the interaction between S atoms in MoS_(2)as well as these O-and N-containing functional groups in N-CQDs with steel surfaces enhanced the stability and strength of tribofilm.Thereby the metal surface was further protected from friction and wear.
基金financially supported by the Distinguished Young Scientists of Hunan Province(No.2022JJ10024)the National Natural Science Foundation of China(No.21601057)+1 种基金the Natural Science Foundation of Hunan Province(No.2021JJ30216)Key Projects of Hunan Provincial Education Department(No.22A0412)。
文摘As prospective energy storage devices,zinc-ion hybrid capacitors(ZHCs)still suffer from unsatisfactory cathode materials.Herein,the three dimensional(3D)N,B dual-doped carbon quantum dots/reduced graphene oxide(N,B-CQDs/rGO)composite aerogel is prepared via a onepot hydrothermal method.Thanks to the synergism of CQDs modification and N,B dual-doping,the resultant N,B-CQDs/rGO composite aerogel delivers superior electrochemical properties.Furthermore,the as-obtained N,B-CQDs/rGO composite aerogel is served as a cathode for aqueous and flexible quasi-solid-state ZHCs for the first time.Impressively,the aqueous N,B-CQDs/rGO//Zn ZHC manifests a large energy density of 96.2 Wh·kg^(-1)at80 W·kg^(-1)and still remains a high energy density of 54.7Wh·kg^(-1)at a superb power density of 80 kW·kg^(-1).Meanwhile,kinetic analyses are employed to elucidate the prominent power performance,and various ex situ tests are undertaken to explore the energy storage mechanism of aqueous ZHC.More notably,the flexible quasi-solid-state N,B-CQDs/rGO//Zn ZHC displays a desirable energy density(89.1μWh·cm^(-2)),a superior power density(96,000μW·cm^(-2))and exceptional flexible performance.The present study offers a valuable reference for designing and developing advanced cathode materials for aqueous and flexible quasi-solid-state ZHCs.
基金supported by the National Natural Science Foundation of China under Grants No.11774304,No.61905206,No.12064048,and No.11804294.
文摘Colloidal quantum dots(CQDs)are of great interest to photovoltaic(PV)technologies as they possess the benefits of solution-processability,size-tunability,and roll-to-roll manufacturability,as well as unique capabilities to harvest near-infrared(NIR)radiation.During the last decade,lab-scale CQD solar cells have achieved rapid improvement in the power conversion efficiency(PCE)from~1%to 18%,which will potentially exceed 20%in the next few years and approach the performance of other PV technologies,such as perovskite solar cells and organic solar cells.In the meanwhile,CQD solar cells exhibit long lifetimes either under shelf storage or continuous operation,making them highly attractive to industry.However,in order to meet the industrial requirements,mass production techniques are necessary to scale up the fabrication of those lab devices into large-area PV modules,such as roll-to-toll coating.This paper reviews the recent developments of large-area CQD solar cells with a focus on various fabrication methods and their principles.It covers the progress of typical large-area coating techniques,including spray coating,blade coating,dip coating,and slot-die coating.It also discusses next steps and new strategies to accomplish the ultimate goal of the low-cost large-area fabrication of CQD solar cells and emphasizes how artificial intelligence or machine learning could facilitate the developments of CQD solar cell research.
基金financial support from the National Natural Science Foundation of China(Nos.81970985,81771122,81601613,21501123)Science&Technology Support Program of Sichuan Province(Nos.2018SZ0037,19YYJC2625)+2 种基金the Graduate Student’s Research and Innovation Fund of Sichuan University(No.2018YJSY108)the China Postdoctoral Science Foundation Funded Project(No.2018M640931)the Science&Technology Key Research and Development Program of Sichuan Province(No.2019YFS0142)。
文摘The carbon quantum dots(CQDs)and their functionalized materials are promising in biomedical field because of their unique properties;meanwhile,a growing concern has been raised about the potential toxicity of these modified materials in biosystem.In this study,we synthesized original CQDs and two common functionalized CQDs including N-doped CQDs(NCQDs)and folic acid-modified CQDs(FACQDs),and compared the toxicity and biocompatibility with each other in vitro and in vivo.L929,C6 and normal cell MDCK were selected to detect the adverse reaction of these materials in vitro.No acute toxicity or obvious changes were noted from in vitro cytotoxicity studies with the dose of these CQD materials increasing to a high concentration at 1 mg/mL.Among these materials,the FA-CQDs show a much lower toxicity.Moreover,in vivo toxicity studies were performed on the nude mice for 15 days.The experimental animals in 10 or 15 mg/kg groups were similar with animals treated by phosphate buffer solution(PBS)after 15 days.The results of the multifa rious biochemical parameters also suggest that the functionalized products of CQDs do not influence the biological indicators at feasible concentration.Our findings in vitro and in vivo through toxicity tests demonstrate that CQDs and their modified materials are safe for future biological applications.
