Enzymeless electrochemical detection of hazardous nitrite by platinum nanoparticle - jute carbon modified glassy carbon electrode

Abstract

In recent years, nitrite (NO2−) pollution has become a subject of great concern for human lives, involving a number of fields, such as environment, food industry and biological process. However, the effective in other words, enzymeless detection of NO2− is an urgent demand as well as an unprecedented challenge. In this work, a novel electrochemical NO2− sensor based on platinum nanoparticle coated carboxylated activated jute carbon (PtNP_CAJC) derived from sustainable jute biomass was successfully fabricated. The biomass derived activated jute carbon was achieved by carbonization of jute sticks at 850 oC using NaHCO3 as activating agent and the resulting mass was further functionalized by acid treatment. Surface morphology and chemical composition of PtNP_CAJC were studied by field emission scanning electron microscopy (FE-SEM), energy dispersive X-Ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). Electron transfer capacity at the interface of the PtNP_CAJC coated electrode was studied by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. It was observed that, PtNP_CAJC nanocomposite thus formed have nanosheet structure having enormous pores of size below 200 nm, and the Pt nuclei that grew over CAJC surface have spherical pattern. The composite has the C, Pt, O, Sn and Cl elements where O, C and Pt are the essential components. The obtained PtNP_CAJC/GCE electrode exhibited a large number of electrocatalytic sites, endowing it with excellent performances for NO2− detection. The electro active surface area of the electrode was found to be 0.066 cm2. The sensor showed a low detection limit of 0.079 µM, superior linear current response and high sensitivity (0.11 µA cm-2 µM-1for 4.99 to 706.05 µM and 0.35 µA cm-2 µM-1 for 778.09 µM to 4.23 mM) for NO2−. In addition, the PtNP_CAJC coated glassy carbon electrode (GCE) i.e., PtNP_CAJC/GCE sensor was applied and evaluated in the determination of NO2− in real environmental samples viz., tap water employing the CV technique. The experimental results have demonstrated the good reproducibility and long-term stability of the PtNP_CAJC/GCE electrode sensor thus fabricated. It was also observed that the selectivity of the sensor electrode for NO2− remained unaffected even if the concentration of interference species were twenty times higher than that of NO2− in the system. The sensor could provide a practical way for rapid and effectively monitoring NO2− quantitatively in real field applications.