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

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

doi:10.1016/j.jcis.2024.03.114

Cited by 5 publications

(11 citation statements)

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“…The biochar was prepared from corncobs under pyrolysis with a limited O 2 atmosphere (20% O 2 ) and activated with a second pyrolysis step, after mixing with KOH in a ratio of KOH/biochar = 3/1. The activation temperature was 850 • C. More details about the biochar preparation and activation can be found in [38].…”

Section: Biochar and Electrode Preparationmentioning

confidence: 99%

“…The collected biochar was used to prepare electrodes through deposition on CC with a dimension of 1 cm × 1 cm with the same procedure as in [38]. The same procedure was followed for the preparation of the CB/CC electrode by replacing the biochar with carbon black.…”

Section: Biochar and Electrode Preparationmentioning

confidence: 99%

“…The physicochemical characterization of biochar was performed using Scanning Electron Microscopy (SEM) (JEOL, JSM-6300, JEOL USA, Inc., Peabody, MA, USA), X-ray Photoelectron Spectroscopy (XPS) (SPECS Phoibos 100-1D-DLD, SPECS Surface Nano Analysis GmbH, Berlin, Germany), porosimetry, (Tristar 3000 porosimeter, Micromeritics, Norcross, GA, USA), X-ray diffraction (XRD) (Bruker D8 (Billerica, MA, USA)), Fouriertransform infrared (FTIR) (Perkin Elmer Spectrum RX FTIR system Waltham, MA, USA) and Raman spectroscopy (Jobin-Yvon Horiba LabRam-HR, Lille, France). Details can be found in [38].…”

Section: Physicochemical Characterizationsmentioning

confidence: 99%

“…Biochar electrode studies have become very popular in the last few years since the use of an abundant, inexpensive material originating from residual biomass is very attractive. Some applications like direct carbon fuel cells and supercapacitors have been reported [34][35][36][37][38]. The high SSA is a desirable characteristic but not crucial for the efficiency of the electrode.…”

Section: Introductionmentioning

confidence: 99%

“…Indeed, in a recent article [38] we reported the electrochemical behaviour of two KOH-activated biochars from olive tree twigs and spent malt rootlets. Both had high lignin content, and the treatment with KOH did result in a high SSA.…”

Section: Introductionmentioning

confidence: 99%

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Study of the Suitability of Corncob Biochar as Electrocatalyst for Zn–Air Batteries

Soursos,

Kottis,

Premeti

et al. 2024

Batteries

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There has been a recent increasing interest in Zn–air batteries as an alternative to Li-ion batteries. Zn–air batteries possess some significant advantages; however, there are still problems to solve, especially related to the tuning of the properties of the air–cathode which should carry an inexpensive but efficient bifunctional oxygen reduction (ORR) and oxygen evolution (OER) reaction electrocatalyst. Biochar can be an alternative, since it is a material of low cost, it exhibits electric conductivity, and it can be used as support for transition metal ions. Although there is a significant number of publications on biochars, there is a lack of data about biochar from raw biomass rich in hemicellulose, and biochar with a small number of heteroatoms, in order to report the pristine activity of the carbon phase. In this work, activated biochar has been made by using corncobs. The biomass was first dried and minced into small pieces and pyrolyzed. Then, it was mixed with KOH and pyrolyzed for a second time. The final product was characterized by various techniques and its electroactivity as a cathode was determined. Physicochemical characterization revealed that the biochar had a hierarchical pore structure, moderate surface area of 92 m2 g−1, carbon phase with a relatively low sp2/sp3 ratio close to one, and a limited amount of N and S, but a high number of oxygen groups. The graphitization was not complete while the biochar had an ordered structure and contained significant O species. This biochar was used as an electrocatalyst for ORR and OER in Zn–air batteries where it demonstrated a satisfactory performance. More specifically, it reached an open-circuit voltage of about 1.4 V, which was stable over a period of several hours, with a short-circuit current density of 142 mA cm−2 and a maximum power density of 55 mW cm−2. Charge–discharge cycling of the battery was achieved between 1.2 and 2.1 V for a constant current of 10 mA. These data show that corncob biochar demonstrated good performance as an electrocatalyst in Zn–air batteries, despite its low specific surface and low sp2/sp3 ratio, owing to its rich oxygen sites, thus showing that electrocatalysis is a complex phenomenon and can be served by biochars of various origins.

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Section: Biochar and Electrode Preparationmentioning

confidence: 99%

Section: Biochar and Electrode Preparationmentioning

confidence: 99%

Section: Physicochemical Characterizationsmentioning

confidence: 99%