Dual role of hemin in Pt nanoparticle deposition on carbon nanotubes for methanol electro-oxidation and oxygen reduction

Abstract

This paper presents a novel and simple non-covalent method to synthesize a double-cladding coaxial structured hybrid by depositing Pt nanoparticles on hemin-coated multi-walled carbon nanotubes (MWCNTs). The Pt nanoparticles cooperated with hemin can be used for methanol electro-oxidation and oxygen reduction. Transmission electron microscopy showed that the Pt nanoparticles were uniformly dispersed on the hemin-coated MWCNTs with a small particle size and a narrow particle size distribution. Cyclic voltammetry tests revealed that the as-prepared Pt/hemin-coated MWCNT electrocatalysts exhibited higher electrochemical surface area (67.46 m2/g) and current density (425.0 mA mg−1) for methanol oxidation than Pt/MWCNTs. These improvements can be attributed to the dual role of hemin in the dispersion of Pt nanoparticles on functionalized MWCNTs and the synergy of catalysis in methanol electro-oxidation and oxygen reduction. It's the first time to report the functionalization of CNTs with catalytic hemin as the binder between CNTs and the metal nanoparticles of MOR or ORR catalyst.