Studies On Several Nanomaterial Modified Electrodes For Electroanalytical Chemistry

Ascorbic acid plays an important role in keeping healthy of human body, Cd, Pb and As are important environmental pollutants, and the analysis of them is thus of important practical significance. In recent years, nanomaterials have found wider and wider applications in the fields of chemistry and biochemistry. Herein, we prepared several nanomaterials for electrochemical analysis. The main researches are as follows.1. A new nanocomposite film that is highly electroactive in neutral aqueous solutions was prepared based on multiwalled carbon nanotubes (MWCNTs), polyaniline (PANI) and mercaptosuccinic acid (MSA). Briefly, a glassy carbon electrode (GCE) was firstly cast-coated with MWCNTs (MWCNTs/GCE), PANI was then electrodeposited on MWCNTs/GCE, and finally MSA was tethered to the electrooxidized PANI via the thiol-ene reaction to form MSA-PANI/MWCNTs/GCE. The high electroactivity of MSA-PANI/MWCNTs/GCE observed in neutral aqueous solutions is ascribed to the anionic MSA tethered in the PANI backbones as well as the good conductivity and high specific surface area of MWCNTs. The prepared MSA-PANI/MWCNTs/GCE electrode was successfully used for catalytic electroanalysis of ascorbic acid (AA) at neutral pH. Under optimum conditions, the anodic amperometric detection of AA provides a linear detection range from20μM to29.6mM, a sensitivity with363μA mM-1cm-2and a limit of detection (LOD) with0.6μM (S/N=3) as well as good reproducibility and stability, which are superior to many reported AA electrochemical sensors.2. A new nanocomposite film was prepared based on electroreduced graphene oxide (ERGO) and2,5-dimercapto-1,3,4-thiadiazole (DMcT). Briefly, a GCE was first cast-coated with graphene oxide (GO), the GO was then electroreduced to ERGO. The thus-prepared ERGO/GCE was then immersed into DMcT solution to absorb monolayer DMcT. The adsorbed DMcT was finally electropolymerized to form a poly(DMcT) modified electrode, PDMcT-ERGO/GCE. The PDMcT-ERGO/GCE electrode was successfully used for the determination of Cd2+and Pb2+. Under optimized conditions, the linear detection range was1-50μg L-1with a sensitivity of0.78μA μg-1L and a LOD of0.05μg L-1(S/N=3) for Cd2+; the linear detection range was1-50μg L-1with a sensitivity of0.64μA μg-1L and a LOD of0.1μg L-1(S/N=3) for Pb2+.3. A new porous nanofilm was prepared based on polyaniline (PANI) and HAuCl4. Briefly, aniline was first electropolymerized on a GCE to form a PANI/GCE, Au was then potentiostatically deposited onto the PANI/GCE by electroreduction of HAuCl4to form an Au/PANI/GCE, and the Au/PANI/GCE was subsequently treated with HNO3to selectively dissolve PANI and finally formed a Aupor/GCE. The thus-prepared Aupor/GCE was successfully used for the dual-signal determination of As(Ⅲ). Under optimized conditions, the cycle voltammetric stripping peak current for As(0)-As(Ⅲ) oxidation was linear with As(Ⅲ) concentration from4.5-375μg L/1with a sensitivity of158μAμM-1and a LOD of0.32μg L-1(S/N=3); and that for the As(Ⅲ)-As(Ⅴ) oxidation was linear with As(Ⅲ) concentration from3-75μg L-1with a sensitivity of85.4μA μM-1and a LOD of0.55μg L-1(S/N=3).