Studies of selectivity of oxygen reduction reaction in acidic electrolyte on electrodes modified by products of pyrolysis of polyacrylonitrile and metalloporphyrins

• Published in: Russian journal of electrochemistry Vol. 52; no. 11; pp. 1007 - 1014
• Main Authors: Davydova, E. S., Tarasevich, M. R.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.11.2016; Springer Nature B.V
• Subjects: Carbon black; Catalysts; Catalytic activity; Catalytic converters; Chemical composition; Chemistry; Chemistry and Materials Science; Electrochemistry; Hydrogen peroxide; Iron; Oxygen reduction reactions; Physical Chemistry; Polyacrylonitrile; Porphyrins; Pyrolysis; Rotating disks; Selectivity; Sulfuric acid; selectivity; catalyst; Co tetramethoxyphenyl porphyrin; RRDE; Fe(III) tetramethoxyphenyl porphyrin chloride; oxygen reduction; polyacrylonitrile; acidic medium
• ISSN: 1023-1935; 1608-3342
• DOI: 10.1134/S1023193516110021

The rotating disk electrode technique was used to study in 0.5 M H 2 SO 4 catalytic properties of products of pyrolysis of the metal-free polyacrylonitrile/carbon black composite, polyacrylonitrile/iron/carbon black composite, and also supported pyropolymers of Co(II) tetramethoxyphenyl porphyrine (CoTMPP) and Fe(III) tetramethoxyphenyl porphyrin chloride (FeTMPPCl). It is shown that the metal-free polyacrylonitrile/carbon black composite catalyzes the oxygen reduction reaction via the parallel path. Addition of up to 2% of Fe into the composite results in abrupt growth of the catalytic activity and share of the four-electron reaction, which provides the parallel–serial reaction path. The parallel reaction with no further catalytic conversion of H 2 O 2 occurs on catalysts of the CoTMPP/Vulcan XC72 and FeTMPPCl/Vulcan XC72 series. The chemical composition is one of the key factors affecting activity and selectivity of CoTMPP/Vulcan XC72 catalysts. An increase in the precursor content from 5 to 30% is accompanied by an increase in selectivity k 1 / k 2 from 0.14–0.30 to 0.5–1.7, where k 1 is the rate constant of the reaction of O 2 reduction to H 2 O, k 2 is the rate constant of the reaction of O 2 reduction to H 2 O 2 .