Fe2O3/3DOM BiVO4: High-performance photocatalysts for the visible light-driven degradation of 4-nitrophenol

Abstract

The three-dimensionally ordered macroporous (3DOM) BiVO4 and its supported iron oxide (xFe2O3/3DOM BiVO4, x=0.18, 0.97, and 3.40wt%) photocatalysts were prepared using the ascorbic acid-assisted polymethyl methacrylate-templating and incipient wetness impregnation methods, respectively. Physicochemical properties of the materials were characterized by means of numerous analytical techniques, and their photocatalytic activities were evaluated for the degradation of 4-nitrophenol under visible light illumination. It is found that the BiVO4 possessed a high-quality 3DOM architecture with a monoclinic crystal phase, and the Fe2O3 was highly dispersed on the surface of 3DOM BiVO4. The xFe2O3/3DOM BiVO4 samples much outperformed the 3DOM BiVO4 sample, and 0.97Fe2O3/3DOM BiVO4 showed the best photocatalytic performance (98% 4-nitrophenol was degraded in the presence of 0.6mL H2O2 within 30min of visible light illumination) and excellent photocatalytic stability. The introduction of H2O2 to the reaction system could promote the photodegradation of 4-nitrophenol by providing the active OH species generated via the reaction of photoinduced electrons and H2O2. The pseudo-first-order reaction rate constants (0.0876–0.1295min−1) obtained over xFe2O3/3DOM BiVO4 were much higher than those (0.0033–0.0395min−1) obtained over 3DOM or Bulk BiVO4 and Fe2O3/Bulk BiVO4, with the 0.97Fe2O3/3DOM BiVO4 sample exhibiting the highest rate constant. The enhanced photocatalytic performance of 0.97Fe2O3/3DOM BiVO4 was associated with its unique porous architecture, high surface area, Fe2O3−BiVO4 heterojunction, good light-harvesting ability, high adsorbed oxygen species concentration, and excellent separation efficiency of photogenerated electrons and holes as well as the photo-Fenton degradation process.