| Two-dimensional planar graphitic carbon nitride(g-C3N4)has been a good candidate for high catalytic active nanocomposites owing to its unique chemical and thermodynamics stability,highly delocalized ?1 conjugated system,structural defects of large pore and proper location of valance band and conduction band.Cu2O,a p-type semiconductor,possesses appropriate oxidation-reduction potential.Nanocomposite based on special morphological Cu2O,which exhibit a good performance of electro-catalytic oxidation attributing to synergistic effects from each component,has a great potential in chemically modified electrodes.In present work,g-C3N4 nanosheets composite and Cu2O special morphological composite were prepared by photoreduction,electrostatic self-assembly and displacement reactions.The structural properties,mechanism of formation and electrochemical detection were discussed deeply.A series of works had been completed as follows:1.Bulk g-C3N4 synthesized by calcining melamine was exfoliated into a two-dimensional layered structure using chemical method.In a mixture of water and isopropyl alcohol,silver ions were in-situ reduced to metallic silver particles(NPs)and anchored onto g-C3N4 nanosheets,forming AgNPs/g-C3N4 composite under UV light irradiation.AgNPs located around the pores of g-C3N4 exhibited good dispersion with particle size about 10 nm.Based on AgNPs/g-C3N4 composite modified glassy carbon electrode,a vanillin sensor was developed.Due to conjugation effect formed between AgNPs and g-C3N4,the ability of charge transport and the separated efficiency of electron-hole were enhanced,which improved the response current and sensitivity.The prepared sensor displayed a wider linear range of 3?180?M and the detection limit was 9.0×10-7M for the determination of vanillin.It exhibited good selectivity and stability,which can be applied in practical milk.2.Cu2O hollow nanospheres(-60nm)with BET specific surface area of 22.84m2/g were prepared from CuCl2 via a liquidphase reduction method with ethylenediamine as ligands of Cu2+.Cu2O@graphene(GN)composite was achieved by efficient electrostatic self-assembly method,where the positive charged Cu2O hollow nanospheres were self-assemblied with the negative charged GN.The response time of Cu2O@GN/GCE was 3 seconds in the electro-catalytic detection for glucose.Amperometric responses were linear with the glucose concentration in a range from 8×10-6 to 2×10-4M,a detection limit of 5.3?M(S/N=3),a sensitivity of 24.6?A/mM.Compared to pure Cu2O hollow nanospheres,Cu2O@GN composite exhibited a better sensitivity,longtime-stability and anti-interference performance.3.Wet chemistry method was introduced for the preparation of uniform Cu20 nanocubes(?50nm)exposing highly active(111)plane without surfactant.Taking advantage of difference in the reduction potential between Cu2+/Cu2O and PdCl4-/Pd,Pd nanoparticles were in-situ grown onto the surface of Cu2O nanocubes,forming Cu2O@Pd core-shell structures.In such a structure of Cu2O@Pd composite,electrons from Cu2O prefer to concentre on Pd ascribed to schottky junction formed between Cu2O and Pd.It improves its electro-catalytic activity towards glucose.With Cu2O@Pd modified electrode,the amperometric sensing of glucose was realized with a linear response over the concentration range from 5.0×10-6 to 3.8×10-4M,a higher sensitivity of 158.6?A/mM and a lower detection limit of 2.3?M.In addition,the good stability and reproducibility were obtained. |
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