Fabrication And Characterization Of Phthalocyanine-carbon Nanotubes And Its Electrooxidation Of Vanillin

The chemically modified carbon nanotubes with phthalocyanine are hopeful toobtain new types of materials with perfect catalytic properties. In this paper compositematerials of phthalocyanine and multi-walled carbon nanotubes (MWCNTs) weresynthesized and characterized, and then the modified glassy carbon electrodes withcomposite materials were used to study the electrocatalytic oxidation of vanillin (VNL).The main results as follows:1. First, MWCNTs were oxided with mixed acid of concentrated H2SO4/HNO3, thentetraaminophthalocyanines of Co(Ⅱ), Ni(Ⅱ), Cu(Ⅱ) were synthesized. Finally, thecomposite materials were obtained by the reaction of MWCNTs-COOH withtetraaminophthalocyanines, and characterized with FT-IR, UV-Vis spectrum and SEM. InFT-IR spectra of composite materials, the new peak appeared at1645cm-1is assigned tothe C=O stretching of-CONH-group. From UV-Vis spectra, it can be found thatcomposite materials reveal broader B and Q bands of tetraaminophthalocyanines withsignificant red-shifted of36and45nm. SEM pictures show thattetraaminophthalocyanines uniformly assemble on the wall of tubes. All these factsconfirm that the composite materials were successfully synthesized.2. Modified glass carbon electrode (MWCNTs/GCE) was prepared by dropping thewater dispersion of MWCNTs on the surface of BGCE. MWCNTs/GCE exhibitedstrongly enhanced sensitivity towards the detection of VNL, the peak potential of VNLoxidation decreased28mV and peak current increased8.7times compared with BGCE,and the detection limit was estimated to be6.4μmol/L.3. BGCE was modified with CoTAPc, NiTAPc and CuTAPc respectively. And themodified BGCE exhibited strongly enhanced sensitivity towards the detection of VNL.The peak potential of VNL oxidation decreased45,12and21mV and peak currentincreased3.5,6.3and5.6times compared with BGCE, respectively. And the detectionlimit of VNL on pCoTAPc/GCE, pNiTAPc/GCE and pCuTAPc/GCE were estimated to be5.14,4.7and5.31μmol/L.4. CoTAPc-MWCNTs, NiTAPc-MWCNTs and CuTAPc-MWCNTs were used tomodify BGCE by dropping their dispersion on the surface of BGCE, respcctively(CoTAPc-MWCNTs/GCE, NiTAPc-MWCNTs/GCE and CuTAPc-MWCNTs/GCE).The Modified BGCE exhibited strongly enhanced sensitivity towards the detection ofVNL. The results suggested that the most negative potential on CoTAPc-MWCNTs/GCEand the maximum current on NiTAPc-MWCNTs/GCE of VNL. The peak potential ofVNL oxidation decreased61,23and30mV and peak current increased15.2,23and18.7times compared with BGCE, respectively. And the detection limit of VNL onCoTAPc-MWCNTs/GCE, NiTAPc-MWCNTs/GCE and CuTAPc-MWCNTs/GCE wereestimated to be1.7,1.8,2.1μmol/L.