Direct Laser Writing of Chitosan-Borax Composites: Toward Sustainable Electrochemical Sensors

Eoghan Vaughan; Chiara Santillo; Alessandra Imbrogno; Gennaro Gentile; Aidan J Quinn; Saulius Kaciulis; Marino Lavorgna; Daniela Iacopino

doi:10.1021/acssuschemeng.3c02708

Direct Laser Writing of Chitosan-Borax Composites: Toward Sustainable Electrochemical Sensors

ACS Sustain Chem Eng. 2023 Sep 1;11(37):13574-13583. doi: 10.1021/acssuschemeng.3c02708. eCollection 2023 Sep 18.

Authors

Eoghan Vaughan¹, Chiara Santillo², Alessandra Imbrogno¹, Gennaro Gentile³, Aidan J Quinn¹, Saulius Kaciulis⁴, Marino Lavorgna², Daniela Iacopino¹

Affiliations

¹ Tyndall National Institute, University College Cork, Lee Maltings Complex, Dyke Parade, Cork T12R5CP, Ireland.
² Institute for Polymers, Composites and Biomaterials, National Research Council of Italy, P.le E. Fermi 1, 80055 Portici, Italy.
³ Institute for Polymers Composites and Biomaterials, National Research Council of Italy, Via Campi Flegrei 34, 80078 Pozzuoli, Italy.
⁴ Institute for the Study of Nanostructured Materials, National Research Council, Monterotondo Staz., 00015 Rome, Italy.

Abstract

In this study, the laser-induced graphitization process of sustainable chitosan-based formulations was investigated. In particular, optimal lasing conditions were investigated alongside the effect of borax concentration in the chitosan matrix. In all cases, it was found that the obtained formulations were graphitizable with a CO₂ laser. This process gave rise to the formation of high surface area, porous, and electrically conductive laser-induced graphene (LIG) structures. It was found that borax, as a cross-linker of chitosan, enabled the graphitization process when its content was ≥30 wt % in the chitosan matrix, allowing the formation of an LIG phase with a significant content of graphite-like structures. The graphitization process was investigated by thermogravimetric analysis (TGA), Raman, X-ray photoemission (XPS), and Fourier transform infrared (FTIR) spectroscopies. LIG electrodes obtained from CS/40B formulations displayed a sheet resistance as low as 110 Ω/sq. Electrochemical characterization was performed after a 10 min electrode activation by cycling in 1 M KCl. A heterogeneous electron transfer rate, k⁰, of 4 × 10^-3 cm s^-1 was determined, indicating rapid electron transfer rates at the electrode surface. These results show promise for the introduction of a new class of sustainable composites for LIG electrochemical sensing platforms.