Evidence for Visible Light Photochromism of V2O5

A binary oxide, polycrystalline V 2 O 5, has been demonstrated to exhibit visible-light photochromism virtually for the first time. The oxide turns blue-black upon irradiation with visible laser light (514.5 nm) in air due to photoreduction of V 5+, and this effect is confirmed to be irradiation-induced, not heat-induced. This visible-light photochromism is also demonstrated to be repeatable without significant degradation of the effect.