It has been demonstrated that the conductivity and electrochemical properties of TiO2 nanomate rials can be significantly improved by an incorporation of carbon additives.In the study,we develop a novel Ndoped TiO2 me...It has been demonstrated that the conductivity and electrochemical properties of TiO2 nanomate rials can be significantly improved by an incorporation of carbon additives.In the study,we develop a novel Ndoped TiO2 mesoporous nanostructure via the addition of carbon quantum dots(CQDs)solution following a scalable hydrothermal process.The as-made TiO2 product shows well-defined morphology,high conductivity,large surface area,and abundant mesopores.When evaluated as anodes for sodiumion batteries,the CQDs@TiO2 product annealed at 500℃exhibits a superior sodium storage capability.It delivers a high reversible capacity of 168.8 mAh/g at 100 mA/g over 500 cycles and long cycling stability.The remarkable performance of CQDs@TiO2 mainly arises from the large surface area and mesoporous architecture constructed by ultrathin TiO2 nanosheets,as well as the full coope ration between CQDs and TiO2.展开更多
Graphene quantum dots(GQDs)/Ni(OH)_(2) composites on carbon cloth(G-NH//CC) are prepared through simple hydrothermal reactions. The resulting G-NH//CC is employed as a binder-free electrode of supercapacitors. Due to ...Graphene quantum dots(GQDs)/Ni(OH)_(2) composites on carbon cloth(G-NH//CC) are prepared through simple hydrothermal reactions. The resulting G-NH//CC is employed as a binder-free electrode of supercapacitors. Due to the enhanced electrical conductivity and efficient ion transport by the addition of GQDs, the G-NH//CC electrode exhibits enhanced electrochemical performances. Specifically, the GNH//CC delivers a maximum specific capacitance of 1825 F g^(-1) at a current density of 1 A g^(-1) as well as a good cycle stability of 83.5 % capacity retention after 8000 cycles. Additionally, all-solid-state symmetric supercapacitor(SSC) is assembled with G-NH//CC composites as both positive and negative electrodes.The fabricated SSC exhibits a high energy density of 80.8 Wh kg^(-1)at a power density of 2021 W kg^(-1). The present study provides a facile and efficient strategy to prepare high-performance electrode materials for advanced electrochemical energy storage devices.展开更多
A series of organic compounds were successfully immobilized on an N-doped graphene quantum dot (N-GQD) to prepare a multifunctional organocatalyst for coupling reaction between CO_(2)and propylene oxide (PO).The simul...A series of organic compounds were successfully immobilized on an N-doped graphene quantum dot (N-GQD) to prepare a multifunctional organocatalyst for coupling reaction between CO_(2)and propylene oxide (PO).The simultaneous presence of halide ions in conjunction with acidic-and basic-functional groups on the surface of the nanoparticles makes them highly active for the production of propylene carbonate (PC).The effects of variables such as catalyst loading,reaction temperature,and structure of substituents are discussed.The proposed catalysts were characterized by different techniques,including Fourier transform infrared spectroscopy (FTIR),field emission scanning electron microscopy/energy dispersive X-ray microanalysis (FESEM/EDX),thermogravimetric analysis (TGA),elemental analysis,atomic force microscopy (AFM),and ultraviolet–visible (UV-Vis) spectroscopy.Under optimal reaction conditions,3-bromopropionic acid (BPA) immobilized on N-GQD showed a remarkable activity,affording the highest yield of 98%at 140℃ and 106Pa without any co-catalyst or solvent.These new metal-free catalysts have the advantage of easy separation and reuse several times.Based on the experimental data,a plausible reaction mechanism is suggested,where the hydrogen bonding donors and halogen ion can activate the epoxide,and amine functional groups play a vital role in CO_(2)adsorption.展开更多
Lithium-ion capacitors(LICs) of achieving high power and energy density have garnered significant attention. However, the kinetics unbalance between anode and cathode can impede the application of LICs. Vanadium nitri...Lithium-ion capacitors(LICs) of achieving high power and energy density have garnered significant attention. However, the kinetics unbalance between anode and cathode can impede the application of LICs. Vanadium nitride(VN) with a high theoretical specific capacity(~ 1200 m Ah·g^(-1)) is a better pseudocapacitive anode to match the response of cathode in LICs. However, the insertion/extraction of Li-ions in VN's operation results in significant volume expansion. Herein, the VN/N-r GO-5composite that three-dimentional(3D) dicyandiamidederived-carbon(DDC) tightly wrapped VN quantum dots(VN QDTs) on two-dimentional(2D) reduced graphene oxid(r GO) was prepared by a facile strategy. The VN QDTs can reduce ion diffusion length and improve charge transfer kinetics. The 2D r GO as a template provides support for nanoparticle dispersion and improves electrical conductivity. The 3D DDC tightly encapsulated with VN QDTs mitigates agglomeration of VN particles as well as volume expansion. Correspondingly, the LICs with VN/Nr GO-5 composite as anode and activated carbon(AC) as cathode were fabricated, which exhibits a high energy density and power density. Such strategy provides a perspective for improving the electrochemical properties of LIC anode materials by suppressing volume expansion and enhancing conductivity.展开更多
Recently,the issue of bacterial resistance has gotten worse because of the overuse of antibiotics.The newborn superbacteria,such as vancomycin-resistant bacteria,were hard to kill,inspiring researchers to find new way...Recently,the issue of bacterial resistance has gotten worse because of the overuse of antibiotics.The newborn superbacteria,such as vancomycin-resistant bacteria,were hard to kill,inspiring researchers to find new ways to kill the bacteria efficiently.TiO_(2) was used as an efficient photocatalyst for water split-ting and pollutant degradation.However,the weak efficiency limited the application to solve the drug-resistance problem.Consequently,the incorpora-tion of low-cost 0D carbon quantum dots(CQDs)and 2D graphene oxide(GO)was pursued to amplify the visible light absorption capabilities of TiO_(2) and thereby elevate its photocatalytic activity.After forming the heterogeneous interface of CQDs and TiO_(2),CQDs converted part of visible light into wave-length less than 400 nm using the up-conversion property.The modification of CQDs enabled electrons to be easily transferred from the conduction band of CQDs to the conduction band of TiO_(2).Meanwhile,GO can act as an electron acceptor,reduce the recombination efficiency of holes and electrons,and transfer the photogenerated electrons in the redox reaction in the heterogeneous interface.Because of the excellent absorption of GO,TiO_(2)/CQDs/GO reached 57.8℃after 20 min irradiation under 1.5 times sunlight,which provided a prerequisite for photodynamic antibacterial therapy/photothermal antibacterial therapy synergistic antibacterial potential.TiO_(2)/CQDs/GO possessed an anti-bacterial efficiency as high as 99.3%toward Staphylococcus aureus which has a bright future in disinfection in vivo and medical devices as well as water sterilization.展开更多
基金financial support from the Shuguang Program supported by Shanghai Education Development Foundation and Shanghai Municipal Education Commission(No.18SG035)Shanghai Pujiang Program(No.17PJD015)。
文摘It has been demonstrated that the conductivity and electrochemical properties of TiO2 nanomate rials can be significantly improved by an incorporation of carbon additives.In the study,we develop a novel Ndoped TiO2 mesoporous nanostructure via the addition of carbon quantum dots(CQDs)solution following a scalable hydrothermal process.The as-made TiO2 product shows well-defined morphology,high conductivity,large surface area,and abundant mesopores.When evaluated as anodes for sodiumion batteries,the CQDs@TiO2 product annealed at 500℃exhibits a superior sodium storage capability.It delivers a high reversible capacity of 168.8 mAh/g at 100 mA/g over 500 cycles and long cycling stability.The remarkable performance of CQDs@TiO2 mainly arises from the large surface area and mesoporous architecture constructed by ultrathin TiO2 nanosheets,as well as the full coope ration between CQDs and TiO2.
基金supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by The Ministry of Education (NRF-2018R1D1A1B07047042)。
文摘Graphene quantum dots(GQDs)/Ni(OH)_(2) composites on carbon cloth(G-NH//CC) are prepared through simple hydrothermal reactions. The resulting G-NH//CC is employed as a binder-free electrode of supercapacitors. Due to the enhanced electrical conductivity and efficient ion transport by the addition of GQDs, the G-NH//CC electrode exhibits enhanced electrochemical performances. Specifically, the GNH//CC delivers a maximum specific capacitance of 1825 F g^(-1) at a current density of 1 A g^(-1) as well as a good cycle stability of 83.5 % capacity retention after 8000 cycles. Additionally, all-solid-state symmetric supercapacitor(SSC) is assembled with G-NH//CC composites as both positive and negative electrodes.The fabricated SSC exhibits a high energy density of 80.8 Wh kg^(-1)at a power density of 2021 W kg^(-1). The present study provides a facile and efficient strategy to prepare high-performance electrode materials for advanced electrochemical energy storage devices.
基金supported by Iran National Science Foundation(No.97015707)。
文摘A series of organic compounds were successfully immobilized on an N-doped graphene quantum dot (N-GQD) to prepare a multifunctional organocatalyst for coupling reaction between CO_(2)and propylene oxide (PO).The simultaneous presence of halide ions in conjunction with acidic-and basic-functional groups on the surface of the nanoparticles makes them highly active for the production of propylene carbonate (PC).The effects of variables such as catalyst loading,reaction temperature,and structure of substituents are discussed.The proposed catalysts were characterized by different techniques,including Fourier transform infrared spectroscopy (FTIR),field emission scanning electron microscopy/energy dispersive X-ray microanalysis (FESEM/EDX),thermogravimetric analysis (TGA),elemental analysis,atomic force microscopy (AFM),and ultraviolet–visible (UV-Vis) spectroscopy.Under optimal reaction conditions,3-bromopropionic acid (BPA) immobilized on N-GQD showed a remarkable activity,affording the highest yield of 98%at 140℃ and 106Pa without any co-catalyst or solvent.These new metal-free catalysts have the advantage of easy separation and reuse several times.Based on the experimental data,a plausible reaction mechanism is suggested,where the hydrogen bonding donors and halogen ion can activate the epoxide,and amine functional groups play a vital role in CO_(2)adsorption.
基金financially supported by the National Natural Science Foundation of China (Nos.22005167 and 21905152)Shandong Provincial Natural Science Foundation of China (Nos.ZR2020QB125, ZR2020MB045 and ZR2022QE003)+2 种基金China Postdoctoral Science Foundation (Nos.2021M693256, 2021T140687 and 2022M713249)Qingdao Postdoctoral Applied Research Project, Taishan Scholar Project of Shandong Province of China (No.tsqn202211160)the Youth Innovation Team Project for Talent Introduction and Cultivation in Universities of Shandong Province。
文摘Lithium-ion capacitors(LICs) of achieving high power and energy density have garnered significant attention. However, the kinetics unbalance between anode and cathode can impede the application of LICs. Vanadium nitride(VN) with a high theoretical specific capacity(~ 1200 m Ah·g^(-1)) is a better pseudocapacitive anode to match the response of cathode in LICs. However, the insertion/extraction of Li-ions in VN's operation results in significant volume expansion. Herein, the VN/N-r GO-5composite that three-dimentional(3D) dicyandiamidederived-carbon(DDC) tightly wrapped VN quantum dots(VN QDTs) on two-dimentional(2D) reduced graphene oxid(r GO) was prepared by a facile strategy. The VN QDTs can reduce ion diffusion length and improve charge transfer kinetics. The 2D r GO as a template provides support for nanoparticle dispersion and improves electrical conductivity. The 3D DDC tightly encapsulated with VN QDTs mitigates agglomeration of VN particles as well as volume expansion. Correspondingly, the LICs with VN/Nr GO-5 composite as anode and activated carbon(AC) as cathode were fabricated, which exhibits a high energy density and power density. Such strategy provides a perspective for improving the electrochemical properties of LIC anode materials by suppressing volume expansion and enhancing conductivity.
基金supported by the China National Funds for Distinguished Young Scientists(No.51925104)the National Natural Science Foundation of China(NSFC)(No.52173251)+3 种基金NSFC-Guangdong Province Joint Program(Key program No.U21A2084)Yanzhao Young Scientist Project(No.C2023202018)Beijing Natural Science Foundation(No.7232338)the Central Guidance on Local Science and Technology Development Fund of Hebei Province(No.226Z1303G).
文摘Recently,the issue of bacterial resistance has gotten worse because of the overuse of antibiotics.The newborn superbacteria,such as vancomycin-resistant bacteria,were hard to kill,inspiring researchers to find new ways to kill the bacteria efficiently.TiO_(2) was used as an efficient photocatalyst for water split-ting and pollutant degradation.However,the weak efficiency limited the application to solve the drug-resistance problem.Consequently,the incorpora-tion of low-cost 0D carbon quantum dots(CQDs)and 2D graphene oxide(GO)was pursued to amplify the visible light absorption capabilities of TiO_(2) and thereby elevate its photocatalytic activity.After forming the heterogeneous interface of CQDs and TiO_(2),CQDs converted part of visible light into wave-length less than 400 nm using the up-conversion property.The modification of CQDs enabled electrons to be easily transferred from the conduction band of CQDs to the conduction band of TiO_(2).Meanwhile,GO can act as an electron acceptor,reduce the recombination efficiency of holes and electrons,and transfer the photogenerated electrons in the redox reaction in the heterogeneous interface.Because of the excellent absorption of GO,TiO_(2)/CQDs/GO reached 57.8℃after 20 min irradiation under 1.5 times sunlight,which provided a prerequisite for photodynamic antibacterial therapy/photothermal antibacterial therapy synergistic antibacterial potential.TiO_(2)/CQDs/GO possessed an anti-bacterial efficiency as high as 99.3%toward Staphylococcus aureus which has a bright future in disinfection in vivo and medical devices as well as water sterilization.
