Green synthesized SiO2/Bi2O3 nanocomposite sensor for catechol and hydroquinone detection in water

Abstract

A new sensitive and selective electrochemical was constructed by modification of the carbon paste electrode (CPE) with SiO2/Bi2O3 nanocomposite (SiO2/Bi2O3/CPE) to quantify catechol (CT) and hydroquinone (HQ). The green synthesized SiO2 and Bi2O3 nanoparticles were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron (SEM) and transmission electron (TEM) microscopy. Results indicated the formation of amorphous spherical SiO2 NPs and crystalline spherical Bi2O3 NPs with particle sizes of 6 and 25 nm, respectively. Cyclic voltammetry results showed the greater electrochemical activity of SiO2/Bi2O3/CPE compared with CPE, SiO2/CPE, and Bi2O3/CPE. This is due to the synergistic effect of SiO2/Bi2O3 nanocomposite leading to larger electroactive surface area. CT and HQ were determined using differential pulse voltammetry (DPV) in phosphate buffer solution at pH 7.2 in the linear ranges of 8.0 ×10−9 - 5.0 ×10−6 M and 5.0 ×10−9 - 5.0 ×10−6 M with the detection limits of 7.0 ×10−10 M and 7.5 ×10−10 M, respectively. The diffusion coefficients of CT and HQ were calculated by chronoamperometry as 1.2 × 10−6 cm2/s and 7 × 10−6 cm2/s, respectively. The sensor demonstrated excellent repeatability and stability allowing the estimation of CT and HQ in Nile river, tap and bottled real water samples with high recoveries.