Publication detail

Intriguing properties of graphite/polysiloxane composite-based pencil electrodes

LI, X. ČECHAL, J. ŠPAŇHEL, L. TOSCANI, S. MARTINÍK, J. OBOŘILOVÁ, R. TRNKOVÁ, L.

Original Title

Intriguing properties of graphite/polysiloxane composite-based pencil electrodes

Type

journal article in Web of Science

Language

English

Original Abstract

Pencil leads can be considered well-defined and cheap graphite electrodes for a wide range of electrochemistry applications. These electrodes display many intriguing properties; however, the origin of these properties is not clear. Using various analytical approaches applied to two different commercially available Tombow (TO) and Staedtler (ST) pencils we reveal a causal relationship between the unique properties of pencils and their graphite/polysiloxane composite. We explore the impact of chloroform etching on chemical composition changes, thermal stability and electrochemical parameters of pencils. Using a combination of X-ray photoelectron spectroscopy (XPS) and gas chromatography-mass spectrometry (GC-MS/MS) various polydimethylsiloxanes in composites are revealed. The polysiloxane species leave into the chloroform solvent during the etching resulting in a significant decrease of their content within the electrodes. Differential scanning calorimetry (DSC) data, corroborated by gravimetric measurements, provide additional proof of the presence of composite structures in ST and TO pencils, showing glass transition temperatures at around 76 degrees C and 81 degrees C. The main difference between the TO and ST electrodes is the content and composition of the polysiloxanes within the graphite matrix. ST composites have significantly higher polymer content (- 30 %) with traces of Na and S impurities compared to TO ones (- 14 %) free of contaminations. Furthermore, mainly cyclic nanostructures appear in chloroform extracts of ST composites whereas rather chain-like clusters are liberated out of the TO counterparts. Complementary electrochemical experiments using cyclic voltammetry (CV), impedance spectroscopy (EIS) and the less known elimination voltammetry with linear scan (EVLS) reflect the performance superiority of TO electrodes with much lower polysiloxane content and free of impurities. High conductivity, low capacitive current along with favoured charge carrier transfer all promise a wide range of technological applications for the TO pencil material.

Keywords

Polysiloxanes; Composites; Pencil graphite electrode; XPS; DSC; GC-MS/MS; EIS; CV; Elimination voltammetry with linear scan; (EVLS); SEM

Authors

LI, X.; ČECHAL, J.; ŠPAŇHEL, L.; TOSCANI, S.; MARTINÍK, J.; OBOŘILOVÁ, R.; TRNKOVÁ, L.

Released

20. 1. 2024

Publisher

PERGAMON-ELSEVIER SCIENCE LTD

Location

OXFORD

ISBN

1873-3859

Periodical

ELECTROCHIMICA ACTA

Year of study

475

Number

1

State

United Kingdom of Great Britain and Northern Ireland

Pages count

12

URL

https://www.sciencedirect.com/science/article/pii/S0013468623017851?via%3Dihub

BibTex

@article{BUT187250,
  author="LI, X. and ČECHAL, J. and ŠPAŇHEL, L. and TOSCANI, S. and MARTINÍK, J. and OBOŘILOVÁ, R. and TRNKOVÁ, L.",
  title="Intriguing properties of graphite/polysiloxane composite-based pencil electrodes",
  journal="ELECTROCHIMICA ACTA",
  year="2024",
  volume="475",
  number="1",
  pages="12",
  doi="10.1016/j.electacta.2023.143615",
  issn="1873-3859",
  url="https://www.sciencedirect.com/science/article/pii/S0013468623017851?via%3Dihub"
}