Electrochemical fabrication of TiO2/TiP2O7 and Ag/TiO2/TiP2O7 nanocomposites for heavy metal detection and methylene blue dye degradation

Abstract

Nanocomposites of titanium dioxide (TO) and titanium pyrophosphate (TPO) have attracted a considerable attention over the past several decades due to their optical properties and high ratio of surface/volume. TO/TPO and Ag/TO/TPO nanocomposites were prepared by electrochemical techniques, followed by electroless deposition of silver. The nanocomposites were discussed by FESEM, TEM, XRD, XPS, FT-IR, Raman, and UV–Vis spectroscopy. XRD and TEM revealed the nanoparticle size of the two composites. Glassy carbon-modified electrode by TO/TPO gave better response than Ag/TO/TPO for the electro-analysis of Pb(II) and Hg(II) as observed by the anodic stripping technique where the detection limit values were 3.09 and 7.46 for Pb(II) and Hg(II), respectively. It was found that the Ag/TO/TPO@GC exhibits an improved sensitivity for the determination of both Pb(II) and Hg(II) ions simultaneously. The presence of O–P–O, Ti–O bonds and the absence of Ti–P were an evidence of the replacement of P atom to Ti atom in their lattice which resulted in forming oxygen vacancies that develop the electrochemical characteristics of the nanocomposite. A slight extension of the absorption edges of TO/TPO into the visible region and a decrease in the band gap gave TO/TPO superior photocatalytic activity for the degradation of methylene blue dye with extent of 99% and a first-order reaction with rate constant 0.01 min⁻¹.