Studies On The Methanol Electrooxidation Catalysts

Fuel cell, an energy conversion device, which can convert chemical energy of fuel into electrical energy by the electrochemical reaction without the combustion, is considered one of the most promising technologies in the 21st century. Among them, the direct methanol fuel cell (DMFC) is one of the most promising fuel cells for large-scale industrialization, with advantages of high energy density, quick starting and high energy conversion efficiency.Electrocatalyst is the key material determines the electrical performance of DMFC. Carbon-supported platinum catalyst (Pt/C) is the most widely used catalyst in the current DMFC. But, the CO poisoning problem of Pt has not been solved during electrochemical oxidation reaction of methanol (MOR) process in he direct methanol fuel cell. In this paper, through material characterization and electrochemical analysis, WO3 modified nitrogen-containing macroporous carbon supported platinum ruthenium catalyst had been developed and influence of platinum and platinum-ruthenium alloy by modification of carbon support on MOR had been analyzed.Macroporous carbon (MPC) materials had been synthesized by different templates on the research. And the influence of templates on MPC pore structure and platinum had been analyzed. The results shown that the catalyst prepared by Nano CaCO3 template had a better catalytic activity. Nitrogen-doped macroporous carbon (N-MPC) had been synthesized and the relationship between nitrogen and platinum had been analyzed. The catalytic activity of nitrogen-doped macroporous carbon-supported platinum catalyst (Pt/N-MPC) increased significantly. Because nitrogen-doped macroporous carbon carrier is more conducive to the dispersion of Pt, and nitrogen can provide O-containing groups in the electrochemical oxidation reaction.The WO3 can not only generate OH, but also modify N-doped carbon carrier which is good for desorption of CO by decreasing the adsorption energy on Pt. Therefore, the Pt loading and N-doped macroporous catalyst modified by WO3 showed higher catalytic activity than Pt/WO3/N-MPC and the performance of CO poisoning was improved. Furthermore, on the basis of the Pt loading and N-doped macroporous catalyst modified by WO3 Platinum-ruthenium alloy can further intensify the formation of OH, so PtRu/W03/N-MPC revealed high catalytic activity. DMFC tests depicted that maximum power density of PtRu/WO3/N-MPC (37.5 wt.% PtRu) could reach 35 mW cm-2 while Pt/WO3/N-MPC (28.6 wt.% Pt)could only reach 28 mW cm"2. Comparing to the commercial PtRu/C(60 wt.% PtRu) catalyst under the same testing condition, the power density can only get 30 mW cm-2.