Biochar from olive tree twigs and spent malt rootlets as electrodes in Zn-air batteries

Theodoros Kottis; Nikolaos Soursos; Katerina Govatsi; Lamprini Sygellou; John Vakros; Ioannis D Manariotis; Dionissios Mantzavinos; Panagiotis Lianos

doi:10.1016/j.jcis.2024.03.114

Biochar from olive tree twigs and spent malt rootlets as electrodes in Zn-air batteries

J Colloid Interface Sci. 2024 Jul:665:10-18. doi: 10.1016/j.jcis.2024.03.114. Epub 2024 Mar 18.

Authors

Theodoros Kottis¹, Nikolaos Soursos¹, Katerina Govatsi², Lamprini Sygellou³, John Vakros⁴, Ioannis D Manariotis⁵, Dionissios Mantzavinos¹, Panagiotis Lianos⁶

Affiliations

¹ Department of Chemical Engineering, University of Patras, 26500 Patras, Greece.
² Laboratory of Electron Microscopy and Microanalysis, School of Natural Sciences, University of Patras 26500 Greece.
³ Foundation of Research and Technology - Institute of Chemical Engineering Science (FORTH/ICE-HT), Stadiou Str. Platani, P.O. Box 1414, Patras 26500, Greece.
⁴ Department of Chemical Engineering, University of Patras, 26500 Patras, Greece. Electronic address: vakros@chemistry.upatras.gr.
⁵ Department of Civil Engineering, Environmental Engineering Laboratory, University of Patras, University Campus 26500 Patras, Greece.
⁶ Department of Chemical Engineering, University of Patras, 26500 Patras, Greece. Electronic address: lianos@upatras.gr.

PMID: 38513404
DOI: 10.1016/j.jcis.2024.03.114

Abstract

Biochars, i.e. porous carbons obtained by pyrolysis of biomass, can act as electrocatalysts for oxygen evolution and oxygen reduction reaction. In the present work, two biochars have been prepared by using materials of completely different biomass origin: olive-tree twigs and spent malt rootlets (brewery wastes). Both biomass species were subjected to pyrolysis under limited oxygen supply and then they were activated by mixing with KOH and pyrolysis again. The obtained biochars were characterized by several techniques in order to determine their structural characteristics and the composition of their active components. Despite their different origin, the two biochars demonstrated similar structural and compositional characteristics thus highlighting the importance of the pyrolysis and activation procedure. Both biochars were used as electrocatalysts in the operation of rechargeable Zn-air batteries, where they also demonstrated similar electrocatalytic capacities with only a small advantage gained by olive-tree-twigs biochar. Compared to bare nanoparticulate carbon (carbon black), both biochars demonstrated a marked advantage towards oxygen evolution reaction.

Keywords: Biochar; Biochar activation; Electrocatalysis; Olive-Tree Twigs; Spent Malt Rootlets; Zn-air batteries.