A novel magnetic electrochemical sensor was designed for determination of lead ions based on gold na- noparticles（AuNPs）@SiO2@Fe3O4/nitrogen-doped graphene（NG） composites functionalized with L-cysteine. The Au@SiO...A novel magnetic electrochemical sensor was designed for determination of lead ions based on gold na- noparticles（AuNPs）@SiO2@Fe3O4/nitrogen-doped graphene（NG） composites functionalized with L-cysteine. The Au@SiO2@Fe3O4/NG was synthesized by the electrostatic adsorption between AuNPs and SiO2-coated Fe304 NPs（SiO2@Fe304） and the amide bond between Au@SiO2@Fe3O4 and NG. L-Cysteine was successfully functionalized on the surface of Au@SiO2@Fe3O4/NG nanocomposites via the S--Au bond between L-cysteine and AuNPs. Owing to numerous active sites in L-cysteines and high conductivity of Au@SiO2@Fe3O4/NG composites, the pro- posed electrochemical sensor exhibited a well-distributed nanostructure and high responsivity toward Pb（II）. The sensor linearly responded to Pb2＋ concentration in the range of 5-80 μg/L with a detection limit of 0.6 μg/L, indicating that this L-cysteine functionalized Au@SiO2@Fe3O4/NG composite could be a promising candidate material for the detection of Pb2＋.展开更多
Fe_(3)O_(4)and Cu_(2)O were successively immobilized on alkali-treated straw,and the magnetically separable straw@Fe_(3)O_(4)/Cu_(2)O composite was obtained.The straw@Fe_(3)O_(4)/Cu_(2)O was characterized by Fourier t...Fe_(3)O_(4)and Cu_(2)O were successively immobilized on alkali-treated straw,and the magnetically separable straw@Fe_(3)O_(4)/Cu_(2)O composite was obtained.The straw@Fe_(3)O_(4)/Cu_(2)O was characterized by Fourier transform infrared spectroscopy,X-ray diffraction,scanning electron microscopy,X-ray photoelectron spectroscopy and vibrating sample magnetometry,respectively.Photocatalytic performance of the straw@Fe_(3)O_(4)/Cu_(2)O was evaluated by measuring the degradation of methyl orange(MO)under irradiation of visible light.The introduction of Fe3O4 not only endowed the straw@Fe_(3)O_(4)/Cu_(2)O with magnetic separation feature but also significantly enhanced photocatalytic activity because Fe3O4 could prevent recombination of hole-electron pairs.The active species capture experiment showed that holes(h+),hydroxyl(∙OH)and superoxide(∙O2ˉ)radicals all took part in the MO degradation.In addition,the photocatalytic mechanism of straw@Fe_(3)O_(4)/Cu_(2)O was proposed based on the experimental results.After five cycles for the photodegradation of MO,the straw@Fe_(3)O_(4)/Cu_(2)O still displayed good photocatalytic activity,suggesting that the as-prepared composite had great potential for practical use in wastewater treatment.展开更多
基金Supported by the National Natural Science Foundation of China（No.31101284）, the Graduate Research and Innovation Foundation of Chongqing, China（No.CYS17017）, the Fundamental Research Funds for the Central Universities of China （Nos. CQDXWL-2012-034, CQDXWL-2012-035, CDJPY12220001） and the Chongqing University Student Research Training Program, China（Nos.CQU-SRTP-2015497, CQU-SRTP-2015502）.
文摘A novel magnetic electrochemical sensor was designed for determination of lead ions based on gold na- noparticles（AuNPs）@SiO2@Fe3O4/nitrogen-doped graphene（NG） composites functionalized with L-cysteine. The Au@SiO2@Fe3O4/NG was synthesized by the electrostatic adsorption between AuNPs and SiO2-coated Fe304 NPs（SiO2@Fe304） and the amide bond between Au@SiO2@Fe3O4 and NG. L-Cysteine was successfully functionalized on the surface of Au@SiO2@Fe3O4/NG nanocomposites via the S--Au bond between L-cysteine and AuNPs. Owing to numerous active sites in L-cysteines and high conductivity of Au@SiO2@Fe3O4/NG composites, the pro- posed electrochemical sensor exhibited a well-distributed nanostructure and high responsivity toward Pb（II）. The sensor linearly responded to Pb2＋ concentration in the range of 5-80 μg/L with a detection limit of 0.6 μg/L, indicating that this L-cysteine functionalized Au@SiO2@Fe3O4/NG composite could be a promising candidate material for the detection of Pb2＋.
基金Science and Technology Project from Ministry of Housing and Urban-Rural Development of the People’s Republic of China(No.2014-K7-007)。
文摘Fe_(3)O_(4)and Cu_(2)O were successively immobilized on alkali-treated straw,and the magnetically separable straw@Fe_(3)O_(4)/Cu_(2)O composite was obtained.The straw@Fe_(3)O_(4)/Cu_(2)O was characterized by Fourier transform infrared spectroscopy,X-ray diffraction,scanning electron microscopy,X-ray photoelectron spectroscopy and vibrating sample magnetometry,respectively.Photocatalytic performance of the straw@Fe_(3)O_(4)/Cu_(2)O was evaluated by measuring the degradation of methyl orange(MO)under irradiation of visible light.The introduction of Fe3O4 not only endowed the straw@Fe_(3)O_(4)/Cu_(2)O with magnetic separation feature but also significantly enhanced photocatalytic activity because Fe3O4 could prevent recombination of hole-electron pairs.The active species capture experiment showed that holes(h+),hydroxyl(∙OH)and superoxide(∙O2ˉ)radicals all took part in the MO degradation.In addition,the photocatalytic mechanism of straw@Fe_(3)O_(4)/Cu_(2)O was proposed based on the experimental results.After five cycles for the photodegradation of MO,the straw@Fe_(3)O_(4)/Cu_(2)O still displayed good photocatalytic activity,suggesting that the as-prepared composite had great potential for practical use in wastewater treatment.
