Study On The Anode Catalyst Of The Direct Methanol Fuel Cells

Pt-based electrocatalysts are usually employed as the anode material to electrocatalytically oxidize methanol. However, due to the fact that Pt anode catalysts are often poisoned by intermediates such as COads produced during methanol oxidation, the use of Pt anode catalysts in such applications is limited because of the slow kinetics of the anode methanol oxidation reaction.Since the favorable efficiency of CeO₂ to improve CO oxidation was reported, many scholars believe that CeO₂ can effectively promote the oxidation of intermediates (CO) produced during methanol oxidation, thereby releasing the active sites on Pt for further electrochemical reaction. In order to decrease the content of Pt, achieve a high dispersion and stability of Pt, we used the well-arranged Carbon nanotubes as the catalysts supporting which were synthesized by anodic aluminum oxide (AAO) templates with glucose as a carbon source in second paragraph. Pt-CeO₂/CNTs hybrid composites with appropriate Pt:CeO₂ molar ratio at 2:1 exhibited high electrocatalytic activities for methanol electro-oxidation.To overcome the problem of Pt poisoning, Au has been examined as a possible alternative substrate metal for electro-oxidation methanol in alkaline media in third paragraph. It has been shown recently that the Au electrode does not undertake poisoning during methanol electrooxidation, because it doesn't electrogenerate COads during the methanol electrooxidation. Recent studied show that the nanosized Au particles exhibit high catalytic activity, we got an Au nanoparticles film on the surface of ITO electrode by MPTMS successfully. Au/ITO electrodes show excellent electrocatalytic activity and stability toward methanol oxidation than bulk Au electrode. We also proposed the process of methanol oxidation on the Au in alkaline solution.In order to improve the electrocatalytic of nanosize Au, we used CeO₂ nanosphere as the supporting of nanosize Au catalyst in forth paragraph. We got core shell structure of Au@CeO₂ successfully, and used Au@CeO₂ as a kind of electrocatalyst in electrooxidation methanol in alkaline media. Electrochemical study indicated that Au@CeO₂ had a better electrocatalytic activity than that of Au/ITO for methanol oxidation in KOH solution. Although the current density of the Au based catalyst is much lower than Pt based catalyst, the catalyst activity will improved greatly by changed the morphologies and the sizes of CeO₂ and gold nanoparticles. It also implies that CeO₂ may be good candidates for noble metal catalyst supports and have potential application in preparing catalysts for direct methanol fuel cells.