A High-Performance, Disposable Screen-Printed Carbon Electrode Modified with Multi-Walled Carbon Nanotubes/graphene for Ultratrace Level Electrochemical Sensors

In this work, a screen-printed carbon paste electrode (SPCE) combined with multi-walled carbon nanotubes (MCNT) and graphene (GP) in different mixing ratios was fabricated. Electrode materials were characterized by scanning electron microscopy as well as Raman spectroscopy and their performance as electrochemical sensors was evaluated by cyclic voltammetry. Results showed that SPCEs composited with 1 w% MCNT and 1 w% graphene achieved the most promising sensing performance for K4FeCN6 with a sensitivity of 0.0054 µA µM−1 and limit of detection (LOD) (3S/N) at 3.1 µM. The so-prepared electrode was then employed to detect H2O2 and nicotinamide adenine dinucleotide (NAD+/NADH) achieving sensitivity and LOD of 0.0027 µA µM−1 and 7.1 µM for H2O2, and 0.0075 µA µM−1 and 3.6 µM for NADH, respectively. Therefore, it was found that the addition of MCNT and graphene to commercial carbon paste for screen printable electrochemical sensor is feasible for fabrication of sensing electrodes for electrochemical detection.