Surfactant-Free Hydrothermal Synthesis of Mesoporous Niobia Samples and Their Photoinduced Decomposition of Terephthalic Acid (TPA)

Abstract

This study introduces a low temperature surfactant-free hydrothermal method to synthesize mesoporous Nb2O5 photocatalysts using NbCl5 and H2O2 as precursors that are subsequently calcinated at 300, 400 and 450 °C and are assigned as mNb2O5-300, mNb2O5-400 and mNb2O5-450, respectively. Commercial niobia sample was used as reference sample for comparison purpose. All of materials were characterized by XRD, SEM, UV–Vis DRS, FTIR, TG/DTG and BET techniques. The synthesized Nb2O5 particles especially mNb2O5-300 sample shows a high surface area (240 m2/g), a large pore volume (0.21 cm3/g) and an identifying morphology of these features. Photocatalytic decomposition of terephthalic acid was evaluated using UV–Vis spectrophotometer. The photocatalytic reactions followed pseudo-first-order kinetics with an apparent rate constant of k = 105 × 10−3 min−1 for mNb2O5-300 sample with the highest activity among all samples at natural pH (pH = 6). Meanwhile, it was observed that optimum pH of 4 resulted in fast photocatalytic reaction for mNb2O5-300 sample.