Enhanced photocatalytic properties of defect-rich α-MoO 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 α-MoO (dr-MoO) nanoflakes with abundant exposed reactive edge sites, by applying cavitation and pitting effect of high-power ultrasonic tip to inch-size α-MoO single crystals. The as-prepared dr-MoO nanoflakes deliver excellent photocatalytic activity for degradation of Rhodamine B (RhB) under visible light irradiation. The degradation apparent rate constant k of dr-MoO is as large as 5.9 × 10 min, which is ˜6.6 times higher than commercial α-MoO (com-MoO). The superior photocatalytic performance of dr-MoO is attributed to its rich exposed edges and slight expansion of interlayer space, which not only enhance the adsorption of HO 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 α-MoO photocatalytic activities, which could be extended to other layered semiconductor photocatalysts.