A novel nanoadsorbent for the removal of heavy metal ions is reported.Cotton was first hydrolyzed to obtain cellulose nanocrystals（CNCs）.CNCs were then chemically modified with succinic anhydride to obtain SCNCs.The...A novel nanoadsorbent for the removal of heavy metal ions is reported.Cotton was first hydrolyzed to obtain cellulose nanocrystals（CNCs）.CNCs were then chemically modified with succinic anhydride to obtain SCNCs.The sodic nanoadsorbent（NaSCNCs） was further prepared by treatment of SCNCs with saturated NaHCO 3 aqueous solution.Batch experiments were carried out with SCNCs and NaSCNCs for the removal of Pb 2＋ and Cd 2＋.The effects of contact time,pH,initial adsorption concentration,coexisting ions and the regeneration performance were investigated.Kinetic studies showed that the adsorption equilibrium time of Pb 2＋ and Cd 2＋ was reached within 150 min on SCNCs and 5 min on NaSCNCs.The adsorption capacities of Pb 2＋ and Cd 2＋ on SCNCs and NaSCNCs increased with increasing pH.The adsorption isotherm was well fitted by the Langmuir model.The maximum adsorption capacities of SCNCs and NaSCNCs for Pb 2＋ and Cd 2＋ were 367.6 mg/g,259.7 mg/g and 465.1 mg/g,344.8 mg/g,respectively.SCNCs and NaSCNCs showed high selectivity and interference resistance from coexisting ions for the adsorption of Pb 2＋.NaSCNCs could be efficiently regenerated with a mild saturated NaCl solution with no loss of capacity after two recycles.The adsorption mechanisms of SCNCs and NaSCNCs were discussed.展开更多
Nanocrystals are emerging as key materials due to their novel shape-and size-dependent chemical and physical properties that differ drastically from their bulk counterparts.The main challenges in this field remain rat...Nanocrystals are emerging as key materials due to their novel shape-and size-dependent chemical and physical properties that differ drastically from their bulk counterparts.The main challenges in this field remain rationally controlled synthesis and large scale production.This article reviews recent progress in our laboratory related to solution-based synthesis of various nanostructures,including zero-dimensional(0-D)nanocrystals,1-D nanowires and nanorods,hollow structures,and superlattice materials.On the other hand,the essential goal for nanoresearchers is to achieve industrial applications of nanostructured materials.In the past decades,these fascinating materials have been widely used in many promising fields such as nanofabrication,nanodevices,nanobiology,and nanocatalysis.Herein,we focus on their applications as nanocatalysts and try to illustrate the main problems and future directions in this area based on our recent endeavors in catalytic applications of nanocrystals.展开更多
Lithium iron phosphate （LiFePO4） is a potential high efficiency cathode material for lithium ion batteries, but the low electronic conductivity and single diffusion channel for lithium ions require good particle siz...Lithium iron phosphate （LiFePO4） is a potential high efficiency cathode material for lithium ion batteries, but the low electronic conductivity and single diffusion channel for lithium ions require good particle size and shape control during the synthesis of this material. In this paper, six LiFePO4 nanocrystals with different size and shape have been successfully synthesized in ethylene glycol. The addition sequence Fe-PO4-Li helps to form LiFePO4 nanocrystals with mostly {010} faces exposed, and increasing the amount of LiOH leads to a decrease in particle size. The electrochemical performance of the six distinct LiFePO4 particles show that the most promising LiFePO4 nanocrystals either have predominant {010} face exposure or high specific area, with little iron（II） oxidation.展开更多
A novel strategy is proposed to directly synthesize water-soluble hexagonal NaYF4 nanorods by doping rare-earth ions with large ionic radius (such as La^(3+), Ce^(3+), Pr^(3+), Nd^(3+), Sm^(3+), Eu^(3+), and Gd^(3+)),...A novel strategy is proposed to directly synthesize water-soluble hexagonal NaYF4 nanorods by doping rare-earth ions with large ionic radius (such as La^(3+), Ce^(3+), Pr^(3+), Nd^(3+), Sm^(3+), Eu^(3+), and Gd^(3+)), and the dopant- controlled growth mechanism is studied. Based on the doping effect, we fabricated water-soluble hexagonal NaYF4:(Yb,Er)/La and NaYF4:(Yb,Er)/Ce nanorods, which exhibited much brighter upconversion fluorescence than the corresponding cubic forms. The sizes of the nanorods can be adjusted over a broad range by changing the dopant concentration and reaction time. Furthermore, we successfully demonstrated a novel depth-sensitive multicolor bioimaging for in vivo use by employing the as-synthesized NaYF4:(Yb,Er)/La nanorods as probes.展开更多
We report a facile way to grow various porous NiO nanostructures including nanoslices,nanoplates,and nanocolumns,which show a structure-dependence in their specific charge capacitances.The formation of controllable po...We report a facile way to grow various porous NiO nanostructures including nanoslices,nanoplates,and nanocolumns,which show a structure-dependence in their specific charge capacitances.The formation of controllable porosity is due to the dehydration and re-crystallization of β-Ni(OH)_(2) nanoplates synthesized by a hydrothermal process.Thermogravimetric analysis shows that the decomposition temperature of the β-Ni(OH)_(2) nanostructures is related to their morphology.In electrochemical tests,the porous NiO nanostructures show stable cycling performance with retention of specific capacitance over 1000 cycles.Interestingly,the formation of nanocolumns by the stacking of β-Ni(OH)_(2) nanoslices/plates favors the creation of small pores in the NiO nanocrystals obtained after annealing,and the surface area is over five times larger than that of NiO nanoslices and nanoplates.Consequently,the specific capacitance of the porous NiO nanocolumns(390 F/g)is significantly higher than that of the nanoslices(176 F/g)or nanoplates(285 F/g)at a discharge current of 5 A/g.This approach provides a clear illustration of the process-structure-property relationship in nanocrystal synthesis and potentially offers strategies to enhance the performance of supercapacitor electrodes.展开更多
A new citrate acid-hydrazine sol-gel route for preparation of Co3O4 nanoparticles has been developed. Co3O4 nanoparticles with different particle-sizes and morphology were prepared at different heat-treatment temperat...A new citrate acid-hydrazine sol-gel route for preparation of Co3O4 nanoparticles has been developed. Co3O4 nanoparticles with different particle-sizes and morphology were prepared at different heat-treatment temperatures and the pure cubic nanocrystals of Co3O4 were obtained at 600℃. The synthesis process was monitored by infrared spectroscopy (IR), thermal gravimetric and differential thermal analysis (TG-DTA). The structure and morphology of Co3O4 nanocrystals were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and X-ray-photoelectron spectroscopy (XPS). The infrared absorption bands blue-shifted with particle size decreasing, which could be attributed to increasing surface effect. XPS results showed that predominant species at surface layers of Co3O4 nanocrystals are octahedral Co (Ⅲ).展开更多
Nanocrystals are pure drug crystals with sizes in the nanometer range. Due to the advantages of high drug loading, platform stability, and ease of scaling-up, nanocrystals have been widely used to deliver poorly water...Nanocrystals are pure drug crystals with sizes in the nanometer range. Due to the advantages of high drug loading, platform stability, and ease of scaling-up, nanocrystals have been widely used to deliver poorly water-soluble drugs. Nanocrystals in the blood stream can be recognized and sequestered as exogenous materials by mononuclear phagocytic system(MPS) cells, leading to passive accumulation in MPS-rich organs, such as liver, spleen and lung. Particle size, morphology and surface modification affect the biodistribution of nanocrystals. Ligand conjugation and stimuli-responsive polymers can also be used to target nanocrystals to specific pathogenic sites. In this review, the progress on injected nanocrystals for targeted drug delivery is discussed following a brief introduction to nanocrystal preparation methods, i.e.,top-down and bottom-up technologies.展开更多
基金supported by the National Basic Research Program (973) of China (No. 2011CB933700) of Ministry of Science and Technology of China
文摘A novel nanoadsorbent for the removal of heavy metal ions is reported.Cotton was first hydrolyzed to obtain cellulose nanocrystals（CNCs）.CNCs were then chemically modified with succinic anhydride to obtain SCNCs.The sodic nanoadsorbent（NaSCNCs） was further prepared by treatment of SCNCs with saturated NaHCO 3 aqueous solution.Batch experiments were carried out with SCNCs and NaSCNCs for the removal of Pb 2＋ and Cd 2＋.The effects of contact time,pH,initial adsorption concentration,coexisting ions and the regeneration performance were investigated.Kinetic studies showed that the adsorption equilibrium time of Pb 2＋ and Cd 2＋ was reached within 150 min on SCNCs and 5 min on NaSCNCs.The adsorption capacities of Pb 2＋ and Cd 2＋ on SCNCs and NaSCNCs increased with increasing pH.The adsorption isotherm was well fitted by the Langmuir model.The maximum adsorption capacities of SCNCs and NaSCNCs for Pb 2＋ and Cd 2＋ were 367.6 mg/g,259.7 mg/g and 465.1 mg/g,344.8 mg/g,respectively.SCNCs and NaSCNCs showed high selectivity and interference resistance from coexisting ions for the adsorption of Pb 2＋.NaSCNCs could be efficiently regenerated with a mild saturated NaCl solution with no loss of capacity after two recycles.The adsorption mechanisms of SCNCs and NaSCNCs were discussed.
基金This work was supported by NSFC(90606006)the State Key Project of Fundamental Research for Nanoscience and Nanotechnology(2006CB932300)the Key Grant Project of the Ministry of Education of P.R.China(No.306020).
文摘Nanocrystals are emerging as key materials due to their novel shape-and size-dependent chemical and physical properties that differ drastically from their bulk counterparts.The main challenges in this field remain rationally controlled synthesis and large scale production.This article reviews recent progress in our laboratory related to solution-based synthesis of various nanostructures,including zero-dimensional(0-D)nanocrystals,1-D nanowires and nanorods,hollow structures,and superlattice materials.On the other hand,the essential goal for nanoresearchers is to achieve industrial applications of nanostructured materials.In the past decades,these fascinating materials have been widely used in many promising fields such as nanofabrication,nanodevices,nanobiology,and nanocatalysis.Herein,we focus on their applications as nanocatalysts and try to illustrate the main problems and future directions in this area based on our recent endeavors in catalytic applications of nanocrystals.
文摘Lithium iron phosphate （LiFePO4） is a potential high efficiency cathode material for lithium ion batteries, but the low electronic conductivity and single diffusion channel for lithium ions require good particle size and shape control during the synthesis of this material. In this paper, six LiFePO4 nanocrystals with different size and shape have been successfully synthesized in ethylene glycol. The addition sequence Fe-PO4-Li helps to form LiFePO4 nanocrystals with mostly {010} faces exposed, and increasing the amount of LiOH leads to a decrease in particle size. The electrochemical performance of the six distinct LiFePO4 particles show that the most promising LiFePO4 nanocrystals either have predominant {010} face exposure or high specific area, with little iron（II） oxidation.
基金The authors thank the Natural Science Foundation of China(Nos.10534030,10904119)the National Program on Key Science Research(No.2006CB921500)and the China Postdoctoral Science Foundation(No.20090451076)for support.
文摘A novel strategy is proposed to directly synthesize water-soluble hexagonal NaYF4 nanorods by doping rare-earth ions with large ionic radius (such as La^(3+), Ce^(3+), Pr^(3+), Nd^(3+), Sm^(3+), Eu^(3+), and Gd^(3+)), and the dopant- controlled growth mechanism is studied. Based on the doping effect, we fabricated water-soluble hexagonal NaYF4:(Yb,Er)/La and NaYF4:(Yb,Er)/Ce nanorods, which exhibited much brighter upconversion fluorescence than the corresponding cubic forms. The sizes of the nanorods can be adjusted over a broad range by changing the dopant concentration and reaction time. Furthermore, we successfully demonstrated a novel depth-sensitive multicolor bioimaging for in vivo use by employing the as-synthesized NaYF4:(Yb,Er)/La nanorods as probes.
基金The authors gratefully acknowledge the AcRF Tier 1 RG 31/08 from Ministry of Education Singapore and No.NRF2009EWT-CERP001-026 Singaporethe National Natural Science Foundation of China(No.20901003)+1 种基金the Natural Science Foundation of the Educational Department of Anhui Province(No.KJ2008B167)the Young Teacher Program of Anhui Normal University(No.2009xqnzc19).
文摘We report a facile way to grow various porous NiO nanostructures including nanoslices,nanoplates,and nanocolumns,which show a structure-dependence in their specific charge capacitances.The formation of controllable porosity is due to the dehydration and re-crystallization of β-Ni(OH)_(2) nanoplates synthesized by a hydrothermal process.Thermogravimetric analysis shows that the decomposition temperature of the β-Ni(OH)_(2) nanostructures is related to their morphology.In electrochemical tests,the porous NiO nanostructures show stable cycling performance with retention of specific capacitance over 1000 cycles.Interestingly,the formation of nanocolumns by the stacking of β-Ni(OH)_(2) nanoslices/plates favors the creation of small pores in the NiO nanocrystals obtained after annealing,and the surface area is over five times larger than that of NiO nanoslices and nanoplates.Consequently,the specific capacitance of the porous NiO nanocolumns(390 F/g)is significantly higher than that of the nanoslices(176 F/g)or nanoplates(285 F/g)at a discharge current of 5 A/g.This approach provides a clear illustration of the process-structure-property relationship in nanocrystal synthesis and potentially offers strategies to enhance the performance of supercapacitor electrodes.
基金This work was financially supported by the Program of International Cooperation of Science & Technology between China and Ukraine (No. 043-05)the Joint Program between the Educational Committee and Economic Trade Committee of Gansu Provience (No. CX-
文摘A new citrate acid-hydrazine sol-gel route for preparation of Co3O4 nanoparticles has been developed. Co3O4 nanoparticles with different particle-sizes and morphology were prepared at different heat-treatment temperatures and the pure cubic nanocrystals of Co3O4 were obtained at 600℃. The synthesis process was monitored by infrared spectroscopy (IR), thermal gravimetric and differential thermal analysis (TG-DTA). The structure and morphology of Co3O4 nanocrystals were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and X-ray-photoelectron spectroscopy (XPS). The infrared absorption bands blue-shifted with particle size decreasing, which could be attributed to increasing surface effect. XPS results showed that predominant species at surface layers of Co3O4 nanocrystals are octahedral Co (Ⅲ).
文摘Nanocrystals are pure drug crystals with sizes in the nanometer range. Due to the advantages of high drug loading, platform stability, and ease of scaling-up, nanocrystals have been widely used to deliver poorly water-soluble drugs. Nanocrystals in the blood stream can be recognized and sequestered as exogenous materials by mononuclear phagocytic system(MPS) cells, leading to passive accumulation in MPS-rich organs, such as liver, spleen and lung. Particle size, morphology and surface modification affect the biodistribution of nanocrystals. Ligand conjugation and stimuli-responsive polymers can also be used to target nanocrystals to specific pathogenic sites. In this review, the progress on injected nanocrystals for targeted drug delivery is discussed following a brief introduction to nanocrystal preparation methods, i.e.,top-down and bottom-up technologies.
