Sonochemical synthesis of nickel tungstate (NiWO4) nanoparticles for dye degradation and electrochemical sensing of lead ions in environmental samples

Abstract

Here we have synthesised Nickel Tungstate (NiWO4) nanoparticles via sonochemical method. The structural and morphological studies were examined using XRD, FTIR, UV–Vis, SEM and TEM analysis. XRD pattern confirms the monoclinic wolframite structure of NiWO4 nanoparticles. FTIR spectrum reveals that strong absorption peaks at 450 cm−1 to 1000 cm−1 for stretching and bending vibrational frequencies of the Ni–W-O peaks in NiWO4. UV–Vis spectrum shows maximum intensity peak at ∼ 473 nm corresponding to the band gap of 3.0 eV. The SEM and TEM images show irregular shapes of nanoparticles. BET analysis shows a surface area 31.811 m2/g for NiWO4 nanomaterials. Methylene Blue (MB) and Rhodamine B (RhB) dyes were used as model pollutants for the analysis of photocatalytic activity under UV and visible light irradiations and it has proved as a fine photocatalyst. The electrochemical activity of the samples was studied by cyclic voltammetry (CV) and Electrochemical Impedance spectroscopy (EIS) in 1 M KOH aqueous electrolyte. EIS measurements showed a reduction in the charge transfer resistance in acidic electrolyte. Modified carbon paste electrode employing NiWO4 nanoparticles has sensed lead in alkaline electrolyte. The electrode displayed high sensitivity for lead detection under varying concentrations. These results confirm that the NiWO4 nanoparticles are promising electrode material for sensing lead with high electrode reversibility.