Photoinduced oxidation of nickel in Ni(II)EDTA with TiO2 nanoparticles

Abstract

TiO2 nanoparticles are well-known for their attractive photocatalytic properties for degradation of adsorbed species. Another area of interest is the use of TiO2 nanoparticles for preparation of photoelectrochromic materials, which are those designed to reversibly change color upon illumination and change of applied potential. This work explored conditions of photo-induced reactions of Ni(II)EDTA in the presence of TiO2 nanoparticles and detected a reversible oxidization reaction to Ni(III)EDTA as a result ultraviolet and visible irradiation. Once irradiation was terminated, the Ni(III)EDTA complex reverted back to Ni(II)EDTA, demonstrating its reversibility. The progress of the reaction was monitored by UV–vis absorption spectroscopy. The photo-induced oxidation reaction was examined for the effect of irradiation time, solution pH and metal–ligand complex concentration. The reaction favors acidic conditions and can be detected for concentrations on the order to 10-3 to 10-1 M Ni(II)EDTA.