Water-Phase Exfoliated Biochar Nanofibers from Eucalyptus Scraps for Electrode Modification and Conductive Film Fabrication
Qurat Ul Ain Bukhari, Filippo Silveri, Flavio Della Pelle, Annalisa Scroccarello, Daniele Zappi, Enrico Cozzoni, Darío Compagnone
Abstract
A solvent-free strategy to produce water-dispersed biochar-nanofibers (BH-CNF) is reported, demonstrating the potential of this cost-effective and sustainable material in electrochemical sensing and fabrication of conductive films. Water-phase BH-CNF from eucalyptus scraps were achieved using a Kraft process followed by liquid-phase exfoliation assisted by the biological stabilizing agent sodium cholate. BH-CNF-based sensors were constructed following two strategies: surface modification of screen-printed electrodes and fabrication of exclusively nanofiber-based flexible sensors. The latter were fabricated through a procedure that is cost-effective and within everyone’s reach. The potentiality of the BH-CNF-based sensors has been challenged toward a wide range of analytes containing phenol moieties and applied for detection of o-diphenols and m-phenols in olive oil samples. The BH-CNF-based sensors exhibited repeatable (RSD ≤ 7%, n = 5) and reproducible (RSD ≤ 10%; n = 3) results, proving their applicability in electroanalytical applications and the robustness of the exfoliation and fabrication strategy. For sample analysis, LODs for hydroxytyrosol (LOD ≤ 0.6 μM) and tyrosol (LOD ≤ 3.8 μM), intersensor precision (RSD calibration slope < 7%, n = 3), and recoveries obtained in real sample analysis (91–111%, RSD ≤ 6%; n = 3) endorse the material exploitability in real analytical applications.