Study On Compound And Function Of Pt - Supported Pt Catalyst For Direct Methanol Fuel Cell

Solving the problems of energy crisis and environmental pollution requires clean and efficient new energy technologies. So many research have been done to develop the clean and renewable energy and related devices and technologies. The research on DMFC is devoted to solving the problems of low catalytic activity and short life of its catalysts. In this dissertation, this paper is devoted to improving the catalytic activity, stability of the catalysts by combining CeO2 with carbon nanotubes and functionalized modification on CeO2.A novel structural of hybrid nanotube with CNTs and CeO2 was successfully synthesized and the hybrid nanotube used as support of Pt nanoparticles displayed an extraordinary conductivity, mechanical properties and thermostability. The experimental results show that the Pt/CeO2-CNTs-HN catalyst exhibits higher activity and better durability than the Pt/CeO2-CNTs-PB, Pt/CNTs and Pt/CeO2-NTs catalysts. The significantly enhanced activity can be attributed to:(ⅰ) more homogeneous distribution of the Pt nanoparticles over CeO2-CNTs-HN support leads to smaller size of Pt; and (ⅱ) the fact that Pt nanoparticles contacted with CeO2 and carbon simultaneously can accelerate the process of methanol electro-oxidation. And there are two reasons accounting for the supreme durability for methanol oxidation:(ⅰ) the stronger van der Waals interaction between Pt and CeO2 inhibits the agglomeration and detachment of Pt; and (ⅱ) the interaction among Pt, CeO2 and carbon mitigates the CO heavily poisoning of Pt. The effects of the CeO2 to CNTs weight ratios and the calcination temperature on the performance of the Pt/CeO2-CNTs-HN catalyst were discussed. The experimental results show that the appropriate ratio was 4:4 and the optimal temperature was 280℃.The activity and durability of the catalysts with carbon used as support will decrease when they operate in the acid environment because they can be corrupted by acid. To improve the stability of the catalyst, we used CeO2 as support and modified the CeO2 support using PVP as nitrogen-doped carbon source. The effect of the doped amount of PVP on the activity and durability of Pt/CeO2@C-N catalysts was discussed through comparison among Pt/CeO2 and Pt/CeO2 catalysts coated with different contents of PVP. The experimental results shows that the appropriate doped amount of PVP is 20 wt.% and PVP also facilitates to improving the activity and durability of the Pt/XC-72 catalyst.