Innovative modification of the surface of screen-printed carbon electrodes by nanofilms directly deposited in cold acrylonitrile plasma

Abstract

This work describes a pioneering example of the application of plasma-enhanced chemical vapor deposition (PECVD) for the direct modification of commercially available screen-printed carbon electrodes (SPCEs) with plasma-deposited (polymerized) acrylonitrile (pp-AN) nanofilms. The developed method enables fast and simple deposition of the films directly on the surface of the working electrode with excellent reproducibility and repeatability. The films were deposited at various plasma power levels (P = 10–80 W) and deposition times (2–4 min), with thicknesses in the range 50–500 nm. The films were characterized in terms of surface morphology (SEM and AFM analysis) and DC electrical conductivity. The cyclic voltammetry measurements performed in the presence of [Fe(CN)6]4−\\3− indicated that, depending on the type of deposited film, the sensors have radically different electrochemical properties. An electrode covered with pp-AN film deposited at P = 10 W with a thickness of approx. 60 nm exhibits the highest sensitivity of the materials studied, and has a favorable peak current ratio, an improved peak separation value, and a well-developed surface area. In general, sensors with pp-AN films deposited at P ≥ 40 W show the microelectrode effect (characterized by the sigmoidal shape of cyclic voltammograms). The excellent homogeneity and mechanical durability of the resulting nanofilms, as well as their outstanding long-term stability (up to six months), demonstrate that PECVD technology offers a real opportunity for the mass production of sensors that can be almost freely functionalized to provide properties such as selectivity and sensitivity.