Structural, Optical, Catalytic, and Pigment Properties of Ca-Doped V₂O₅ Nanostructures

Calcium (Ca)-doped vanadium pentoxide (Ca-V₂O₅) nanostructures were prepared by using egg-shell waste as a Ca-source. X-ray diffraction (XRD) analysis of pure V₂O₅ and Ca-V₂O₅ samples reveals the formation of orthorhombic V₂O₅ nanocrystals. Characteristic V-O vibrations were noticed in the Fourier transform infrared (FTIR) spectroscopic study. Morphological investigations confirm the occurrence of heterogenous morphologies (plates and sticks). Light absorption and emission features of the Ca-V₂O₅ samples were assessed by UV-visible absorption and photoluminescence (PL) studies. In order to examine the catalytic activity of Ca-V₂O₅ samples, hydrogen peroxide (H₂O₂)-mediated oxidative degradation of methylene blue and Congo red was selected as model catalytic reactions. 5Ca-V₂O₅ powder achieved 96.8% methylene blue degradation efficiency within 10 min, whereas 2Ca-V₂O₅ powder attained 78.8% Congo red degradation efficiency within 15 min. The reasons for catalytic performance of Ca-V₂O₅ samples were explored. The pigment characteristics of Ca-V₂O₅ samples were also determined and 5Ca-V₂O₅ powder possess a* = 17.68 and b* = 25.46. Ca-dopant determines the colour hue of V₂O₅ powder. The Ca-V₂O₅ powder could become an effective catalyst and pigment.