Graphene‐AuNP Enhanced Inkjet‐printed Silver Nanoparticle Paper Electrodes for the Detection of Nickel(II)‐Dimethylglyoxime [Ni(dmgH<sub>2</sub>)] Complexes by Adsorptive Cathodic Stripping Voltammetry (AdCSV)
Keagan Pokpas, Nazeem Jahed, Earl McDonald, Petroné H. Bezuidenhout, Suzanne Smith, Kevin Land, Emmanuel I. Iwuoha
Abstract
Abstract The development of low‐cost, disposable electrode materials has been at the forefront of sensor technology in recent decades. Paper, offers possibilities for multi‐functional, disposable and economically friendly sensing capabilities and has proved to be a suitable reagent storage and substrate material in paper‐based analytical devices (PADs). In this work, we report a simple inkjet printing procedure on photographic paper for the fabrication of single analyte electrochemical sensors. A three‐electrode system, consisting of a 3 mm diameter working electrode (WE), a counter electrode (CE) and a reference electrode (RE) were prepared by inkjet printing of silver conductive inks for comparison to common commercial screen printed electrode (SPE) brands. In a second step, carbon coating and modification of the working electrode surface with an electrochemically reduced graphene oxide, gold nanoparticle (ERGO‐AuNP) film, to improve electrode sensitivity and selectivity was employed. Improved electron‐transfer kinetics, increased active surface area and enhanced catalytic properties were achieved due to the ERGO‐AuNP layer inclusion. Electrical and topographical characterization of the printed layers was performed in the fabrication process. Printing of Ag−NP ink showed good resistivity (1.8–6.3 Ω) on photographic paper. The prepared printed paper‐based electrodes (PPE) offer a quantitative analysis of Ni(II), based on the accumulation of Ni(dmgH) 2 complexes at the modified electrode surface by square‐wave adsorptive cathodic stripping voltammetry (SW‐AdCSV). This study offers the first investigation on the feasibility of adsorptive electrochemical sensing methods at porous cellulose paper‐based substrates. Instrumental parameters including deposition potential and deposition time were optimized for both electrochemical sensors. Improved sensitivities were achieved at the modified integrated electrodes over the unmodified derivate with a limit of detection (LOD) of 32.19 μg L −1 achieved for the ERGO‐AuNP−CC−Ag−PPE. This is well below the EPA and WHO standards of 0.1 mg L −1 or 0.1 ppm for Ni 2+ in drinking water.