求化学翻译

Graphite powder (<20m)， hydrazine， ammonia， N，Ndimethylformamide (DMF)， dopamine， 0.01M phosphate buffered saline (PBS; 0.138M NaCl， 0.0027M KCl， pH 7.4)， and ascorbic acid were purchased form Aldrich and used as received. Doubly disti... Graphite powder (<20m)， hydrazine， ammonia， N，Ndimethylformamide (DMF)， dopamine， 0.01M phosphate buffered saline (PBS; 0.138M NaCl， 0.0027M KCl， pH 7.4)， and ascorbic acid were purchased form Aldrich and used as received. Doubly distilled water was used throughout the whole experiments. The data of cyclic voltammetry (CV)， differential pulse voltammetry (DPV)， and electrochemical impedance spectra were obtained with a CHI 660 electrochemical workstation (CH instruments， Austin， TX). The electrochemical cell consisted of GCE (3mm diameter， Bioanalytical Systems， Inc.) as working electrode， Ag/AgCl (Bioanalytical Systems， Inc.) as reference electrode， and platinum wire as counter electrode. The impedance data were fitted to an appropriate equivalent circuit using ZsimpWin 3.0 software (Echem Software). The Raman spectra of graphene were obtained by micro-Raman system equipped with a homemade sample stage， a monochromator (SPEX 500 M)， and a CCD camera (Roger Scientific model 7346-001) with 514.5nm wavelength laser line. Graphene was characterized by field emission scanning electron microscope (SUPRA 55VP， Carl Zeiss) and atomic force microscope (NanostationII， Surface Imaging Systems).