Alternative platinum electrocatalyst supporter with micro/nanostructured polyaniline for direct methanol fuel cell applications

In this study, a series of micro/nanostructured polyanilines were synthesized and their morphology-dependent electrochemical properties for acting as a catalyst supporter for direct methanol fuel cell (DMFC) applications were investigated. These micro/nanostructures include submicron spheres, hollow microspheres, nanotubes, and nanofibers. Among the four micro/nanostructures, polyaniline nanofibers (PANF) manifest their superiority in high electrochemical active surface. Accordingly, PANF is adopted as the catalyst supporter thereafter. To couple with the use of the alternative catalyst supporter, this study also investigates the effect of reductant type on morphology and electrocatalytic properties of the PANF-supported Pt particles through a chemical reduction reaction. TEM images indicate that formic acid as a reductant results in well-dispersed Pt particles on the PANF surface. On the other hand, aggregations of Pt are observable when NaBH4 is selected as a reductant. Moreover, the methanol oxidation current density measured with the Pt/PANF electrode being prepared by using formic acid is double that by using NaBH4. Compared with Pt/XC-72, the Pt/PANF electrode possesses higher electrocatalytic activity and exhibits double power density. Moreover, Pt/PANF is superior to Pt/XC-72 in the aspect of operation stability based on a continuous discharge for 5 h.

► We report the synthesis of a series of micro/nanostructured polyanilines and the investigation of their morphology-dependent electrochemical properties.
► Formic acid as a reducing agent results in well-dispersed Pt particles on the PANF surface and a higher electrolytic ability of Pt/PANF than that of NaBH4.
► Pt/PANF is superior to Pt/XC-72 in the aspect of operation stability of direct methanol fuel cell based on a continuous discharge for 5 h.