Enhanced photocatalytic properties of defect-rich α-MoO3 nanoflakes by cavitation and pitting effect

For the first time, we present a novel, facile and eco-friendly engineering defect method, to produce defect-rich alpha-MoO3 (dr-MoO3) nanoflakes with abundant exposed reactive edge sites, by applying cavitation and pitting effect of high-power ultrasonic tip to inch-size alpha-MoO3 single crystals. The as-prepared dr-MoO3 nanoflakes deliver excellent photocatalytic activity for degradation of Rhodamine B (RhB) under visible light irradiation. The degradation apparent rate constant k of dr-MoO3 is as large as 5.9 x 10(-2) min(-1), which is similar to 6.6 times higher than commercial alpha-MoO3 (com-MoO3). The superior photocatalytic performance of dr-MoO3 is attributed to its rich exposed edges and slight expansion of interlayer space, which not only enhance the adsorption of H2O and OH-, provide abundant highly reactive sites, but also shorten the distance of photogenerated carriers moving to the reactive sites. This work provides new insights into the self-enhancement of alpha-MoO3 photocatalytic activities, which could be extended to other layered semiconductor photocatalysts.