Photocatalytic reduction of Cr(VI) using Nb2O5 under UV irradiation: Influence of polymorphs
Year: 2025
Type: conference-paper
Abstract: This paper discusses the influence of niobium pentoxide (Nb2O5) polymorphs on Cr(VI) photoreduction under UV. The tetragonal Nb2O5 (M-Nb2O5) and monoclinic Nb2O5 (H-Nb2O5) were synthesized by thermal oxidation of Nb powders at 200 - 1000 °C in a tube furnace under the air atmosphere. The morphology and crystal structure of the annealed Nb powders were examined using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) analysis. Phase percentages of the phase were determined using X’pert Highscore Plus software via the Rietveld refinement method. Cr(VI) concentration was measured colorimetrically using UV-Visible spectroscopy. SEM results showed closed-packed rod-like structures for samples annealed at 400 - 1000 °C. XRD revealed that both tetragonal and monoclinic Nb2O5 structures co-existing at 400 - 1000 °C. Rietveld refinement analysis indicated an increase in H-Nb2O5 and a decrease in M-Nb2O5 with rising temperatures, suggesting a transformation from tetragonal to monoclinic Nb2O5 at higher temperatures. Photocatalytic tests demonstrated that the sample synthesized at 1000 °C achieved the highest Cr(VI) removal rate of 62% after 150 min, attributed to the higher photoactivity of monoclinic Nb2O5 than tetragonal Nb2O5.
Authors: Nurulhuda Bashirom, Abdul Hakim Zakaria
Institution: Universiti Malaysia Perlis
Language: English
Field: Energy
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W4408673750