Investigation On The Fabrication Of Dissolved Oxygen Sensors Based On Carbon Materials

The measurement of dissolved oxygen in aqueous solutions is important for different fields of application in particular for Environmental protection,sewage disposal,medical treatment and clinical analysis. Investigations have been take place into determining oxygen concentration via titrimetry, spectrometry and chemiluminescence. Modified electrode has attached much attention of people in recent years for its high sensitivity, selectivity, and fast response.In this thesis, hemoglobin and noble metal particles as oxygen sensitive indicator were modified on the surface of substrate electrode to form new oxygen sensors. The thesis consists of following two parts. In part one, direct electron transfer of Hb between RTIL modified electrode was discussed: RTIL modified basal plane graphite electrode (BPG) was immersed in Hb from its solution to form an Hb/RTIL/Nafion electrode. The progress of adsorption was monitored by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The Hb/RTIL/Nafion modified BPG electrode can catalyze the electroreduction of O2 with a significant lowering of overpotential. With the addition of sol-gel membrane onto the RTIL membrane, the obtained Hb/sol/RTIL/Nafion modified BPG electrode has a better activity towards oxygen and better stability.In part two, the preparation of a new type of composite nano-material was discussed: new type of composite nano-material modified electrodes was constructed by electrochemical deposition of gold,silver and platinum nanoparticles to MWNTs modified electrode, respectively. The progress of electrodeposition was monitored by transmission electron microscopy method (TEM) and cyclic voltammetry (CV). The highly dispersed noble metal nanoparticles on MWNTs exhibited a good electrocatalytic activity for the reduction of O2 and good stability...