Surface Selective Polymerization of Polypyrrole on Ordered Mesoporous Carbon: Enhancing Interfacial Conductivity for Direct Methanol Fuel Cell Application

Abstract

Ordered mesoporous carbon (OMC) selectively covered on the outer surface with polypyrrole (PPy) was prepared by removing the mesoporous silica template after the polymerization of pyrrole adsorbed on the surface of mesoporous silica−carbon composite. The amounts of PPys loaded on OMCs increased with the polymerization time and adsorption time. The resulting PPy−OMC composite maintained regular mesopore structure and high surface area of the OMC. The electrical resistance of PPy−OMC showed a lower value than that of pristine OMC; however, at high loading amount of PPy, the resistance rised to the value of pristine OMC. The PPy−OMC was successfully used as supports for Pt metal particles with a size of 2.8 nm, which illustrated that inner pores of the OMC were effectively utilized for supporting Pt catalyst particles even in the presence of PPy. Furthermore, the electrochemically active surface area obtained from the cyclic voltammogram of Pt catalyst loaded in the PPy−OMC was much higher than that of a commercial catalyst. The Pt-loaded PPy−OMC catalyst exhibited 50% enhanced power density compared to the commercial Pt catalyst in a direct methanol fuel cell (DMFC) single cell test. These results indicated that the PPy−OMC could afford plenty of surface area for supporting the Pt particles in the mesopores, and the Pt particles in PPy−OMCs were applicable to direct methanol fuel cells.