Polyaniline and Perfluorosulfonic Acid Co-Stabilized Metal Catalysts for Oxygen Reduction Reaction

Abstract

A proton (perfluorosulfonic acid, PFSA) and electron (polyaniline, PANI) conductor polymer costabilized Pt catalyst (Pt-PFSA/C@PANI) is synthesized to improve the long-term stability of polymer electrolyte membrane fuel cells (PEMFCs). The prepared catalyst not only displays comparable oxygen reduction reaction (ORR) activity, but significantly higher electrochemical stability than commercial porous carbon nanosphere supported Pt catalysts (Pt/C). This robust electrochemical property can be due to the result of PFSA and PANI. PANI as protector inhibits carbon nanospheres from corrosion of carbon supports in harsh chemical and electrochemical conditions. Meanwhile, PFSA wrapped Pt NPs (Pt@PFSA) can also anchor Pt NPs on C@PANI to avoid aggregation and detachment of Pt NPs, due to the increased metal-support interaction caused by the strong electrostatic attraction between PANI and PFSA with corresponding positive and negative charges. Significantly, after coating PANI on carbon supports (C@PANI), almost all micropores in the surface of carbon disappear, effectively avoiding the embedding of Pt nanopaticles into micropores. Furthermore, the triple-phase boundary toward ORR catalysis can be facilitated by PFSA as proton conductor (solid electrolyte). These are of benefit to increase utilization of Pt noble metals and ORR activity of our new catalysts.

Nitrogen-rich graphitic-carbon@graphene as a metal-free electrocatalyst for oxygen reduction reaction

“…The conducting polymers are widely used in various fields such as energy conversion, energy storage and sensors. Among various conducting polymers, polyaniline (PANI) is particularly interesting due to the low cost, superior stability in alkaline media, and conductivity 24 – 26 . Recently, PANI has also been used as the N-doping agent in metal-free electrochemical ORR catalysts preparation 26 – 29 .…”

“…Among various conducting polymers, polyaniline (PANI) is particularly interesting due to the low cost, superior stability in alkaline media, and conductivity 24 – 26 . Recently, PANI has also been used as the N-doping agent in metal-free electrochemical ORR catalysts preparation 26 – 29 . Although, the N-doped carbon derived from carbonized PANI upon heat treatment and has been applied as ORR catalyst 26 – 29 , but their ORR performances are not as good as other NCMs.…”

“…Recently, PANI has also been used as the N-doping agent in metal-free electrochemical ORR catalysts preparation 26 – 29 . Although, the N-doped carbon derived from carbonized PANI upon heat treatment and has been applied as ORR catalyst 26 – 29 , but their ORR performances are not as good as other NCMs. This is probably due to the serious aggregation and less porous nature with lower amount of active sites in PANI derived carbon which lead to the low exposure to the active sites.…”

A new insight into the stability of nanofiber electrodes used in proton exchange membrane fuel cells

“…We ascribe the super stability of the catalyst in the C-E electrode to the unique nanofiber structure and the existence of PAA, as detailed below. Although particle migration and the coalescence of Pt particles easily occurs during the CV aging process, the carrier polymers in the nanofiber electrodes constrained the migration of platinum ions effectively by the electrostatic interactions and the attachment effects [19] . To some extent, the carrier polymers mitigated the decay of the catalysts in the C-E electrode.…”

“…In the C-S electrode, the severe decay of the carbon supports resulted in the collapse of the proton transport network, leading to the sharp increase of R ion . However, for the C-E electrode, carbon corrosion was effectively alleviated, guaranteeing a relatively stable proton transport network [19,21] . Furthermore, the hydrophilic PAA polymer provided an ideal wetted TPB, with more protons existing on the side nearest to the Pt surface, which also facilitated the transfer of protons considerably [23] .…”