Bi2O3@Bi nanoparticles for ultrasensitive electrochemical determination of thiourea: monitoring towards environmental pollutants

Abstract

Thiourea and other sulphur containing organic molecules are commonly present in industrial waste water and because of their toxic nature are environmental pollutants. Thiourea oxidation constructed on cost effective and proficient catalyst to substitute/alternative with noble metals (Pt, Au, Ir, Rh, Pd and others) based electrodes. Herein, this report for the synthesis of Bi2O3@Bi (∼ 4-5 nm) nanoparticles by using polyfunctional citric acid is a surface protecting molecule for electrocatalytic thiourea oxidation reactions as a one of the environmental hazardous monitoring system at room temperature. These as-synthesized nanoparticles were well characterized by scanning electron microscopy (SEM), Furrier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA) and further studied for electrochemical determination of thiourea (TU). These structural and morphological studies were further confirms the rhombohedral crystal structure with thermogravimetric analysis (TGA) shows 20 wt% citrate molecules on the surface of Bi2O3@Bi nanoparticles. The electrochemical studies on Bi2O3@Bi nanoparticle reveals that, it's having ultra-low detection limit, higher sensitivity and better activity at ultralow potential for a current density of 11.2 mA/cm2 for oxidation of thiourea (TU). Moreover, chronoamphrometric (i-t) measurement shows proposed Bi2O3@Bi based system is having stable and long term current performance at a potential of 0.85 V vs. SCE towards the TU oxidation. This work affords with noble metal free electrocatalyst for novel appliance and remarkable consequence as a thiourea determination and conversion as a part of waste management.