Electrochemical Preparation Of Several Nanomaterials Of Carbon And Carbon-supported Noble Metals And Their Applications

In recent years, carbon and carbon-supported noble metals have attracted wide attention due to their unique physical/chemical properties and are widely used in catalysis, electrochemical sensing, and so on. Until now, many methods have been employed to prepare these materials. Among them, electrochemical method becomes an effective means because of its advantages such as mild preparation conditions and easy control. In this paper, starting from bulk carbon material we prepared the carbon and carbon-supported noble metal nanomaterials and studied their applications in electrocatalysis and electroanalysis. The main contents of the present thesis are as follows:(1) We report a paired electrolysis method to prepare graphite nanoflakes(GNFs) and their supported noble metal/alloy nanoparticles(NM NPs/GNFs), by applying an alternating voltage(AV) on two graphite rod electrodes in a Na OH solution without/with noble metalions. The synthesis of GNFs might be related to the anodic exfoliation of graphite surface via OH- intercalation, accompanying the dispersion effect of hydrogen/oxygen gases evolution. The preparation of NM NPs/GNFs should be resulted from repeated coupling processes, namely the cathodic deposition of NM NPs and the electrochemical exfoliation-dispersion of NM NPs-decorated graphite layer. The GNFs and NM NPs/GNFs exhibited high electrocatalytic activities toward the redox of 4-nitrophenol and oxidation of formic acid, respectively.(2) The prepared graphite nanoflakes(GNFs) modified glass carbon electrode(GNFs/GCE) were used to detect 4-NP by using cyclic voltammetry method, Under optimized detection conditions, the oxidation peak currents varied linearly with a concentration range for 4-NP of 1-6000 μM(over three consecutive calibration curves) with a detection limit of 0.7 μM(3?/slope) and quantification limit of 2.3 μM(10?/slope), The present method exhibited several advantages including very broad linear response range, easy fabrication, low cost, good sensitivity, good reproducibility and high selectivity. The as-fabricated GNFs/GCE can be a potential candidate for the determination of 4-NP in other real samples.(3) A nanoparticulate thin film electrode was facilely fabricated from smooth GC surface in a blank solution of NaOH with square wave potential pulses. This uniform film was composed of dense nanoparticles and decorated with oxygen-containing functional groups, and exhibited high electrochemical activity. Its formation might be related to repeated pulse electrochemical oxidation of GC surface. The parameters including anodic potential, time and frequency of SWPPs for film preparation were examined on CV behaviors of 4-NP redox. The oxidation peak was chosen to the 4-NP determination, and under the optimized conditions, its currents varied linearly with a concentration range for 4-NP of 0.5?3000 ?M(over two consecutive calibration curves) with a detection limit of 0.23 ?M(3?/slope) and quantification limit of 0.77 ?M(10?/slope). The present method based on this film was successfully applied to detect 4-NP in water samples with satisfied results.