Facile synthesis and shape evolution of well-defined phosphotungstic acid potassium nanocrystals as a highly efficient visible-light-driven photocatalyst.

Uniform and hollow rhombic dodecahedral, rhombic dodecahedral, spherical, and semi-hollow K3PW12O40·nH2O nanocrystals are fabricated without any surfactants or templating agents in mild hydrothermal conditions. The shape evolution and growth of these crystals are studied by changing different reaction parameters, such as the reagent, time and temperature. It is found that the temperature and time have significant effects on the possible growth processes of these nanostructures. More importantly, according to photocatalytic results, due to the specific nanostructure-hollow rhombic dodecahedral structure, the hollow rhombic dodecahedral K3PW12O40·nH2O particles with nanopores are shown to be the most effective at activating H2O2, degrading dye pollutants completely after 90 minutes of visible light radiation. What's more, the good recycle lifetime for the hollow rhombic dodecahedral K3PW12O40·nH2O particles makes them practical for industrial applications. Possible mechanisms for the photocatalysis reaction are further discussed.