| Recent years, with the human attention to the environmental protection, the fuel cell (FC) has been got a great progress in the fields of power supply and electric vehicle industry. Direct Methanol Fuel Cell (DMFC) is an important kind of FCs, which is based on a new FC concept. It uses methanol as fuel other than hydrogen and proton exchange membrane as electrolyte. DMFC is regarded as a important aspect of FCs, because it not only remains all the advantages of proton exchange membrane fuel cell(PEMFC), but also does not have problems of fuel transformation and storage in other kind of FCs. At present, the electrode materials used in DMFC have lower electro-catalytic activity of oxidation for methanol and other small organic molecules, so, this thesis studied preparation of new electrocatalytic electrodes with higher electro-catalytic activity and lower cost.The main purposes of this thesis are preparation of high dispersed nano-Pt electrode and nano-WO3 electrode doping with Pt, and electrochemical behaviors of ethanol, methanol, formaldehyde and formic acid on these electrocatalytic electrodes.The main results and conclusions are as follows:1. The first part (Literature Review): (1)Reviewed development history, working principle, classification, applications of the FC, and made a comparison between different kinds of FCs.(2)Summarized the mechanism, present research situation, the prospects of applications and key problems of DMFC.(3)Reviewed the preparation, characterization, working principle, applications of nano-WO3 film and electrocatalytic mechanism of nano-Pt-WO3 film to methanol.2. The second part: The electrocatalysts of nano-Pt was prepared on glassy carbon by electrochemical deposition under cyclic voltammetric condition. Scan voltage range was from -0.25V to 0.40V and scan speed was 50mV.S-1. Thickness of the catalyst film was 12.53nm, the sizes of Pt particles were generally less than 100nm.The electro-oxidation of ethanol on nano-Pt/GC electrode was also investigated. The experimental results demonstrated that this electrode exhibits a high electro-catalytic activity, and the mass current density of nano-Pt/GC electrode is higher ca 5 orders of magnitude than that of the Pt electrode. This electro-catalyst also shows high catalytic activity on methanol, formaldehyde and formic acid. In the cyclic votammetry experiment, the apparent peak current density of oxidation on nano-Pt /GC electrode in methanol solution is ca. 2.5 times larger than that on the Pt electrode.The apparent peak current density of nano-Pt/GC electrode in formaldehyde solution is ca. 1.1 times than that of the Pt electrode. The apparent peak current density of nano-Pt /GC electrode in formic acid solution is ca. 1.2 times larger than that of the Pt electrode.3. The third part: The electrocatalytic electrode of nano-WO3 doping with Pt (nano-Pt-WO3/GC)was prepared by electrochemical deposition controlling constant electrode potential of -0.25V for 30 minutes. The morphology of the nano-Pt-WO3/GC electro-catalyst was parallel columnellas, which made of nano-size particles. The columnella diameter is uniform, less than 1m. It's height was 1.91 m. Nano-Pt-WO3/GC has been applied to the electrochemical oxidation of ethanol. The results demonstrate that this electrode exhibits a higher electro-catalytic activity than that of the nano-Pt electrode. In cyclic voltammogram test, the apparent peak current density on the nano-Pt-WO3/GC electrode is ca. 10 times larger than that on the nano-Pt/GC electrode. When this kind of electrode applied to the electrochemical oxidation of methanol, formaldehyde and formic acid, it is found that nano-WO3/GC has no electro-catalytic activity, however, nano-Pt-WO3/GC has a high electro-catalytic activity to methanol, formaldehyde and formic acid. The apparent current density of oxidation peak on the nano-Pt-WO3/GC electrode in methanol solution is ca. 12.5 times than that on the nano-Pt/GC electrode. The apparent current density of oxidation peak on... |
PDF Full Text Request