Optimisation Study of Co Deposition on Chars from MAP of Waste Tyres as Green Electrodes in ORR for Alkaline Fuel Cells

Maurizio Passaponti,Claudio Fontanesi,Marco Bonechi,Walter Giurlani,Lorenzo Fabbri,Francesca Bruni,Luca Rosi,Gabriele Sciortino,Massimo Innocenti,Leonardo Lari,Martina Vizza,Vlado K Lazarov

doi:10.3390/en13215646

Abstract

Oxygen Reduction Reaction (ORR) catalysts, from waste automobile tyres obtained from Microwave assisted pyrolysis (MAP), were enriched with Co and Cu using the simple treatments sonochemical and electrochemical deposition. Catalytic activity was evaluated through onset potential and number of exchanged electrons measurements. Electrochemical data demonstrate an improvement in catalytic activity of the electrochemical modified char with Co. Char electrodes enriched with Co show a maximum positive shift of 40 mV with respect to raw char electrodes with a number of exchanged electrons per O2 molecule close to 4 (as for Pt) for the best sample. This corresponds to a reduction of the production of unwanted oxygen peroxide from 23% for raw char to 1%. Sample structure evolution before and after electrochemical deposition and electro-catalysis was investigated by scanning transmission electron microscopy and XPS. Such electrochemical treatments open new possibilities of refining waste chars and finding an economic alternative to noble metals-based catalysts for alkaline fuel cells.

Highlights

End of life tyres (ELTs) show a difficult disposal and recycling process
The onset potential represents the limit value at which a reaction starts to evolve in significant quantities while the number of exchanged electrons allows the assessment of the principal reaction pathway in Oxygen Reduction Reaction (ORR)
With the aim of finding an efficient substitute to noble metals in the catalysis of oxygen reduction reaction and at the same time to efficiently recycle waste automobile tyres, efforts have been made to reaction and at the same time to efficiently recycle waste automobile tyres, efforts have been made to strengthen the catalytic activity of chars obtained from Microwave assisted pyrolysis (MAP) of waste tyres

Summary

Introduction

End of life tyres (ELTs) show a difficult disposal and recycling process. Their methods of recovery can be divided in three main types: physical, chemical and thermal. We seek a way of recovering energy from ELTs using pyrolysis [1]. As a result of this process, chars are obtained as discard products. Thermochemical decomposition stimulates a series of radical chain reactions that deconstruct polymers into smaller compounds [2]. The presence of carbon black, an excellent absorber, employed as filler in ELTs, enables the use of microwave pyrolysis, in which electromagnetic energy is transformed into thermal energy [3], and allows uniform heating [4]

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