An ‘ice-melting’ kinetic control strategy for highly photocatalytic organic nanocrystals

Engineering the size, shape and crystallinity of organic semiconductor nanostructures (OSNs) offers the opportunity of fine tuning their optoelectronic properties for photocatalytic applications. Here, we report a facile and general ‘ice-melting’ kinetic control strategy to synthesize OSNs with excellent photocatalytic performance. The ultraslow release and interaction of organic molecules from ice melting yields an ultralow local concentration (∼five orders of magnitude fewer molecules), fundamentally enhancing the energy barrier thus leading to their relaxed and ordered assembly into refined nanocrystals (∼one order of magnitude smaller in size, morphological change from amorphous to crystalline); such nanocrystals display improved light-harvesting and charge transfer properties and consequent photocatalytic efficiency towards degrading organic pollutants compared to standard OSNs, or even commercial titania photocatalysts (Degussa P25); we also generalize the ‘ice-melting’ kinetic control strategy to synthesize a series of highly photoactive organic nanocrystals.