Conductive disposable screen-printed graphene oxide-molybdenum disulfide electrode for electrochemical sensing applications

In this work, a new and convenient fabrication process for screen-printed reduced graphene oxide-molybdenum disulfide electrode (SPrGO-MoS₂E) was proposed. Reduced graphene oxide-molybdenum disulfide (rGO-MoS₂) composite was hydrothermally synthesized and then dispersed in deionized water and ethanol with a ratio of 2:3 (v/v) to form a conductive suspension. The suspension was then blended with carbon paste at a ratio of 0.1:9.9 (g/g) to obtain a screen-printable rGO-MoS₂ conductive ink. An electrochemical sensing electrode was formed by screening this conductive ink onto a polyethylene terephthalate substrate. The characteristics of this electrode were investigated by scanning electron microscopy, energy-dispersive X-ray spectrometry, X-ray diffractometry, Raman spectroscopy, and electrochemical impedance spectroscopy. Overall, the conductive suspension comprising the rGO-MoS₂ composite showed higher electrochemical sensing performance compared with electrodes containing only rGO or MoS₂. Cyclic voltammetry revealed that the SPrGO-MoS₂ electrode exhibited excellent electrochemical sensing performance toward several electroactive species, namely, potassium hexacyanoferrate (III) ([Fe(CN₆)]^3−/4−), nicotinamide adenine dinucleotide (NAD⁺/NADH), and hydrogen peroxide (H₂O₂) dissolved in 0.1 M PBS (pH 7.4). The limits of detection for [Fe(CN₆)]^3−/4−, NAD⁺/NADH, and H₂O₂ were 0.34, 0.25, and 1.36 μM, respectively. In addition, the reproducibility, repeatability, and stability determined from the relative standard deviations (RSDs, n = 7) of these analytes were less than 12.1 %, 8.6 %, and 7.4 %, respectively. Therefore, the ready-to-use SPrGO-MoS₂E could be an alternative material for advanced chemical and biological sensing applications.