Nanocomposite Prepared from In Situ Grafting of Polypyrrole to Aminobenzoyl-Functionalized Multiwalled Carbon Nanotube and Its Electrochemical Properties

Abstract

We reported the functionalization of multiwalled carbon nanotube (MWCNT) with 4-aminobenzoic acid by a "direct'' Friedel-Crafts acylation reaction in a mild polyphosphoric acid (PPA)/phosphorous pentoxide (P2O5) medium. The resulting 4-aminobenzoyl-functionalized MWCNT (AF-MWCNT) was used as a platform for the grafting of polypyrrole (PPy) in ammonium persulfate (APS)/aqueous hydrochloric acid solution to produce PPy-grafted MWCNT (PPy-g-MWCNT) composite. After dedoping with alkaline treatment, PPy-g-MWCNT displayed 20 times higher electrical conductivity than that of PPy. The current density and cycle stability of PPy-g-MWCNT composite were also remarkably improved compared with those of PPy homopolymer, suggesting that an efficient electron transfer between PPy and MWCNT was possible through covalent links. In addition, PPy-g-MWCNT displayed high electrocatalytic activity for oxygen reduction reaction (ORR).