An electrochemical sensor based on a porphyrin dye-functionalized multi-walled carbon nanotubes hybrid for the sensitive determination of ascorbic acid

Abstract

A novel electrochemical sensor was constructed based on a zinc porphyrin dye (YD2-o-C8, designated as YD) functionalized multi-walled carbon nanotubes (MWCNTs) hybrid. YD has a special donor-π-bridge-acceptor planar structure, which is beneficial for the π-π stacking interaction between YD and MWCNTs. The interaction was characterized by UV–vis, fluorescence, Fourier transform infrared (FT-IR) spectroscopy, and electrochemistry. The results showed that YD easily interacted with MWCNTs, which enhanced the electron transfer between YD and the electrode. The obtained YD/MWCNT hybrid was modified on the glassy carbon electrode (GCE) by a surfactant of tetraoctylammonium bromide (TOAB) to fabricate an electrochemical sensor (TOAB/YD/MWCNT/GCE). In the interface material of the sensor, YD acted as an electron intermediate, MWCNTs acted as an electron accelerator, and TOAB was used as an arouser to trigger the inner redox activity of YD. With their synergistic effect, the proposed sensor exhibits excellent electrocatalytic activity for the oxidation of ascorbic acid (AA). At the optimized conditions, the sensor exhibited a linger response to AA in the concentration range from 18.72μM to 1.85mM, high sensitivity of 19.16μAmM−1, and a low limit of determination (0.18μM). Furthermore, the TOAB/YD/MWCNT/GCE exhibited excellent stability and reproducibility for the response of AA in an aqueous solution. The desirable detecting recoveries for vitamin C tablets were obtained from 97.1% to 105.2%, indicating the reliability and feasibility in determining AA in real samples.