Growth of nanocrystalline graphite and vertically aligned graphite nanowalls thin films and their transfer on flexible substrates for applications as electrochemical sensors for anthracene detection

Abstract

Plasma-enhanced chemical vapor deposition (PECVD) allows the growth of nanocrystalline graphite (NCG)-type materials, such as N-doped bulk NCG and graphite nanowalls (GNW), on different substrates (silicon and copper) to develop flexible electrochemical sensors for anthracene detection. The carbonic materials were investigated using different techniques, including X-ray diffraction, small-angle X-ray scattering, scanning electron microscopy, X-ray photoelectron spectroscopy, cyclic voltammetry, and differential pulsed voltammetry (DPV). XRD analysis revealed different crystallinity features for both graphitic materials, as the N-NCG film presented higher lattice strain (1 %) and dislocation density (5.2 × 1012 cm−2), compared to the GNW film with a lattice strain of 0.2 % and dislocation density of 7 × 1011 cm−2. We also present a successful approach for developing flexible electrodes via transfer process from Cu to polyethylene (PE) substrate. The carbonic films were transferred onto flexible substrates via thermal treatment of the Cu foils with the PE layers, followed by Cu etching to reveal the carbon material as the sensing area of the flexible sensors. Electrodes based on N-NCG and GNW grown on silicon and those transferred to PE substrates were investigated at different anthracene concentrations by DPV. The results showed greater performance for anthracene determination in the case of N-NCG/Si, showing a sensibility of 0.8 A⋅M−1 than that of GNW/Si (0.0625 A⋅M−1). However, the flexible GNW/PE electrode exhibited an increased response in DPV in the presence of anthracene, resulting in a higher sensitivity (0.23 A⋅M−1) than that of N-NCG/PE (0.19 A⋅M−1). This behavior suggests the good electrochemical compatibility of the GNW film with the flexible polymeric substrate to obtain a flexible electrochemical sensor for anthracene detection.