Niobium nanoparticles with high purity were prepared by a sodiothermic reduction process using Nb2O5 as the raw material, LiCl, NaCl, KCl and CaCl2 as the diluents and sodium as the reducing reagent. The effects of th...Niobium nanoparticles with high purity were prepared by a sodiothermic reduction process using Nb2O5 as the raw material, LiCl, NaCl, KCl and CaCl2 as the diluents and sodium as the reducing reagent. The effects of the different molten salt systems, CaCl2 content, reaction time, excessive sodium and reaction temperature on the characteristics of the obtained niobium powder were discussed. The as-prepared niobium nanoparticles under the optimum experimental conditions were obtained by sodiothermic reduction with 20% excessive sodium in the NaCl-52mol%CaCl2- 2mol%Nb2O5 molten salts at 650 ℃for 6 h, and the molar ratio of the oxygen element in Nb2O5 and the CaCl2 of the molten salts is less than 19.23% at 750 ℃. Moreover, the particle size of niobium nanoparticles is ranged about 40~240 nm with increasing of reaction temperature from 650 to 800 ℃.展开更多
Glyphosate is a herbicide that has been widely used worldwide and is used in agricultural areas to control weeds and unwanted vegetation.Electrochemical sensors developed from different nanomaterials have high efficie...Glyphosate is a herbicide that has been widely used worldwide and is used in agricultural areas to control weeds and unwanted vegetation.Electrochemical sensors developed from different nanomaterials have high efficiency,excellent cost-benefit,and fast analysis time for detecting traces of environmental pollutants.This study aimed to produce an electrochemical sensor with disposable screen-printed electrodes based on carbon black modified with niobium nanoparticles to determine glyphosate in aqueous solutions.The morphology,structure and electrochemical performance of the sensor were characterized by scanning electron microscopy,energy-dispersive X-ray spectroscopy,X-ray diffraction and cyclic voltammetry.Differential pulse voltammetry in BR buffer solution at pH 5.0 allowed the generation of a method to quantify glyphosate concentration in a linear range of 5.90-172.30μmol/L(1.00-29.13μg/mL),with a limit of detection calculated at 3.07μmol/L(0.52μg/mL).The method efficiently quantified glyphosate in real water samples and showed no interference from K^(+),Na^(+),Ca^(2+),Mg^(2+)ions or thiamethoxam,imidacloprid and carbendazim pesticides.展开更多
Photocatalytic CO_(2) reduction to valuable chemical compounds could be a promising approach for carbon-neutral practice.In this work,a simple and robust thermal decomposition process was developed with ammonium carbo...Photocatalytic CO_(2) reduction to valuable chemical compounds could be a promising approach for carbon-neutral practice.In this work,a simple and robust thermal decomposition process was developed with ammonium carbonate((NH4)2CO3)as both precipitation agent and sacrificial template to produce fine Nb_(2)O_(5) nanoparticles with the rich existence of surface hydroxyl(–OH)groups.It was found by density functional theory(DFT)calculations and experiments that the rich existence of the surface–OH groups enhanced the adsorption of both reactants(CO_(2) and H_(2)O molecules)for the photocatalytic CO_(2) reduction on these fine Nb_(2)O_(5) nanoparticles,and the highly selective conversion of CO_(2) to the high-value chemical compound of ethylene(C_(2)H_(4),~68μmol·g^(−1)·h^(−1) with~100%product selectivity)was achieved under simulated solar illumination without usage of any sacrificial agents or noble metal cocatalysts.This synthesis process may also be readily applied as a surface engineering method to enrich the existence of the surface–OH groups on various metal oxide-based photocatalysts for a broad range of technical applications.展开更多
基金financially supported by the National Science Foundation of China(Nos.51102015and21071014)China Postdoctoral Science Foundation(No.20110490009)+2 种基金Research Fund for the Doctoral Program of Higher Education of China(No.20110006120027)the Program for New Century Excellent Talents in University(No.NCET-11-0577)the Program for Changjiang Scholars and Innovative Research Team in University(No.IRT0708)
文摘Niobium nanoparticles with high purity were prepared by a sodiothermic reduction process using Nb2O5 as the raw material, LiCl, NaCl, KCl and CaCl2 as the diluents and sodium as the reducing reagent. The effects of the different molten salt systems, CaCl2 content, reaction time, excessive sodium and reaction temperature on the characteristics of the obtained niobium powder were discussed. The as-prepared niobium nanoparticles under the optimum experimental conditions were obtained by sodiothermic reduction with 20% excessive sodium in the NaCl-52mol%CaCl2- 2mol%Nb2O5 molten salts at 650 ℃for 6 h, and the molar ratio of the oxygen element in Nb2O5 and the CaCl2 of the molten salts is less than 19.23% at 750 ℃. Moreover, the particle size of niobium nanoparticles is ranged about 40~240 nm with increasing of reaction temperature from 650 to 800 ℃.
基金the Coordenacao de Aperfeicoamento de Pessoal de Nível Superior(CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico(CNPq)Fundacao de Amparo à Pesquisa do Estado do Rio de Janeiro(FAPERJ)(Cincotto Proc.E-26/202.696/2019,Proc.E-26/010.002267/2019 and E-26/210.304/2022)for the financial support
文摘Glyphosate is a herbicide that has been widely used worldwide and is used in agricultural areas to control weeds and unwanted vegetation.Electrochemical sensors developed from different nanomaterials have high efficiency,excellent cost-benefit,and fast analysis time for detecting traces of environmental pollutants.This study aimed to produce an electrochemical sensor with disposable screen-printed electrodes based on carbon black modified with niobium nanoparticles to determine glyphosate in aqueous solutions.The morphology,structure and electrochemical performance of the sensor were characterized by scanning electron microscopy,energy-dispersive X-ray spectroscopy,X-ray diffraction and cyclic voltammetry.Differential pulse voltammetry in BR buffer solution at pH 5.0 allowed the generation of a method to quantify glyphosate concentration in a linear range of 5.90-172.30μmol/L(1.00-29.13μg/mL),with a limit of detection calculated at 3.07μmol/L(0.52μg/mL).The method efficiently quantified glyphosate in real water samples and showed no interference from K^(+),Na^(+),Ca^(2+),Mg^(2+)ions or thiamethoxam,imidacloprid and carbendazim pesticides.
基金This study was supported by the National Natural Science Foundation of China(Grant Nos.52272125 and 51902271)the Fundamental Research Funds for the Central Universities(Grant Nos.2682021CX116,2682020CX07,and 2682020CX08)Sichuan Science and Technology Program(Grant Nos.2020YJ0259,2020YJ0072,and 2021YFH0163).We would like to thank Analysis and Testing Center of Southwest Jiaotong University for the assistance on material characterization.
文摘Photocatalytic CO_(2) reduction to valuable chemical compounds could be a promising approach for carbon-neutral practice.In this work,a simple and robust thermal decomposition process was developed with ammonium carbonate((NH4)2CO3)as both precipitation agent and sacrificial template to produce fine Nb_(2)O_(5) nanoparticles with the rich existence of surface hydroxyl(–OH)groups.It was found by density functional theory(DFT)calculations and experiments that the rich existence of the surface–OH groups enhanced the adsorption of both reactants(CO_(2) and H_(2)O molecules)for the photocatalytic CO_(2) reduction on these fine Nb_(2)O_(5) nanoparticles,and the highly selective conversion of CO_(2) to the high-value chemical compound of ethylene(C_(2)H_(4),~68μmol·g^(−1)·h^(−1) with~100%product selectivity)was achieved under simulated solar illumination without usage of any sacrificial agents or noble metal cocatalysts.This synthesis process may also be readily applied as a surface engineering method to enrich the existence of the surface–OH groups on various metal oxide-based photocatalysts for a broad range of technical applications.
