Ionic self-assembly of metalloporphyrin/heteropolyacid on multi-wall carbon nanotubes with enhanced electrocatalytic activity toward oxygen reduction reaction

Abstract

We report the synthesis of a series of hybrid electrocatalysts toward oxygen reduction reaction (ORR) by ionic self-assembly of positively charged Fe(III) meso-tetra([Formula: see text]-methyl-4-pyridyl)porphyrin (FeP) with negatively charged H3PMo[Formula: see text]O[Formula: see text] (PMo[Formula: see text] in ethanol solution under ambient conditions in the presence of suspended multi-wall carbon nanotubes (MWCNTs). Self-assembled FeP/PMo[Formula: see text] was well-dispersed on MWCNTs with a tunable loading from 26.3% to 55.6%. Interestingly, the hybrid electrocatalysts demonstrated a much higher ORR activity than individual PMo[Formula: see text] and FeP in acidic media. We speculate that this activity enhancement might originate from a possible synergy between PMo[Formula: see text] and FeP. This study may be extended to the design and synthesis of other types of hybrid electrocatalysts for applications in electrochemical energy conversion, storage and sensing.