Biofabricated SnO₂ nanoparticles using Red Spinach (Amaranthus tricolor L.) extract and the study on photocatalytic and electrochemical sensing activity

Biofabrication of SnO₂ nanoparticles (SnO₂ NPs) using Amaranthus tricolor L.) extract has been conducted. Synthesis of the nanoparticles was conducted by refluxing tin chloride dihydrate as SnO₂ precursor followed by calcination at 400 °C. The formation of SnO₂ NPs was identified from UV-Visible spectrophotometric analysis and particle size analyzer. The resulting materials were characterized by x-ray diffraction (XRD), Fourier-Transform Infra-Red (FTIR), scanning electron microscope-energy dispersive x-ray (SEM-EDS), transmission electron microscope (TEM), and diffuse reflectance UV-Visible (UV-DRS). Photocatalytic evaluation of SnO₂ NPs was carried out in a photodegradation of bromophenol blue (BPB) under photocatalytic and photooxidation mechanism with the presence of H₂O₂. Physicochemical analyses confirm the formation of SnO₂ NPs providing the capability to act as photoactive material. The photocatalytic activity studied by UV-Visible spectrophotometric analysis and high performance liquid chromatography (HPLC) revealed the superior activity of the nanoparticles for decomposition of BPB. The decomposition rate of BPB under photooxidation mechanism is higher than of photocatalysis mechanism. Both mechanisms obey pseudo-second order kinetics and the decomposition was identified from the shifted spectra of treated solution. Furthermore, the electrochemical sensing activity for the detection of heavy metal Hg²⁺ showed an increasing of sensitivity and feasibility of the SnO₂/Au electrode compared to the bare Au with the limit of detection of 0.001 970 ppm. This result reveals the facile green synthesis route of SnO₂NPs with the promising activities. (paper)