Three-dimensional ordered macroporous bismuth vanadates: PMMA-templating fabrication and excellent visible light-driven photocatalytic performance for phenol degradation.

Three-dimension ordered macroporous (3D-OM) bismuth vanadates with a monoclinic crystal structure and high surface area (18-24 m(2) g(-1)) have been prepared using ascorbic acid (AA)- or citric acid (CA)-assisted poly(methyl methacrylate) (PMMA)-templating strategy with bismuth nitrate and ammonium metavanadate as the metal sources, HNO(3) as the pH adjuster and ethylene glycol and methanol as the solvent. The materials were characterized by a number of analytical techniques. The photocatalytic performance of the porous BiVO(4) samples was evaluated for the degradation of phenol in the presence of a small amount of H(2)O(2) under visible light illumination. The effects of the initial phenol concentration and the H(2)O(2) amount on the photocatalytic activity of the photocatalyst were examined. It is shown that the chelating agent, AA or CA, and the amount in which it is added had a significant impact on the quality of the 3D-OM structure, with a "(Bi + V):chelating agent" molar ratio of 2:1 being the most appropriate. Among the as-prepared BiVO(4) samples, the one with a surface area of ca. 24 m(2) g(-1) showed the best visible light-driven photocatalytic performance for phenol degradation (phenol conversion = ca. 94% at phenol concentration = 0.1 mmol L(-1) and in the presence of 0.6 mL H(2)O(2)). A higher phenol conversion could be achieved within the same reaction time if the phenol concentration in the aqueous solution was lowered, but an excess amount of H(2)O(2) was not a favorable factor for the enhancement of the catalytic activity. It is concluded that the excellent photocatalytic activity of 3D-OM BiVO(4) is due to the high quality 3D-OM structured BiVO(4) that has a high surface area and surface oxygen vacancy density. We are sure that the 3D-OM material is a promising photocatalyst for the removal of organics from wastewater under visible light illumination. This journal is © The Royal Society of Chemistry 2012