Layered KTiNbO5 photocatalyst modified with transitional metal ions (Mn2 +, Ni2 +): Investigation of microstructure and photocatalytic reaction pathways for the oxidation of dimethyl sulfide and ethyl mercaptan

Abstract

K1−2xMxTiNbO5 (MMn, Ni) photocatalytic material was prepared through a successive ion-exchange reaction of KTiNbO5, which was synthesized by a solid-state reaction, with Mn2+ or Ni2+, respectively. The microstructure and the spectral response characteristic of K1−2xMxTiNbO5 were investigated by means of powder X-ray diffraction (XRD), laser Raman spectroscopy (LRS), and UV–vis diffuse reflectance spectrum (UV–vis DRS). The photocatalytic activities were evaluated by the oxidation of dimethyl sulfide (DMS) and ethyl mercaptan (EM) under natural light (NAT-L) and ultraviolet light (UV-L) irradiation, and the surface species were determined by technology of Fourier-transform infrared (FT-IR) spectroscopy. XRD patterns indicate that ion exchange has changed the interlayer distance. LRS spectra show that there is a significant interaction between the interlayer cation and the terminal NbO bond. DRS spectra reveal that an additional absorption edge, which locates at a longer wavelength region, can be observed for K1−2xMxTiNbO5. For photocatalytic oxidation of DMS and EM, K1−2xNixTiNbO5 has an activity whether under NAT-L or UV-L irradiation. Based on the reactant structure feature and the product distribution, possible reaction pathways of the photocatalytic oxidation for DMS and EM used layered K1−2xMxTiNbO5 catalyst were proposed.