Boosting Hot-Electron Generation: Exciton Dissociation at the Order-Disorder Interfaces in Polymeric Photocatalysts.
Excitonic effects, arising from the Coulomb interactions between photogenerated electrons and holes, dominate the optical excitation properties of semiconductors, whereas their influences on photocatalytic processes have seldom been discussed. In view of the competitive generation of excitons and hot carriers, exciton dissociation is proposed as an alternative strategy for hot-carrier harvesting in photocatalysts. Herein, by taking heptazine-based melon as an example, we verified that enhanced hot-carrier generation could be obtained in semicrystalline polymeric photocatalysts, which is ascribed to the accelerated exciton dissociation at the abundant order-disorder interfaces. Moreover, driven by the accompanying electron injection toward ordered chains and hole blocking in disordered chains, semicrystalline heptazine-based melon showed an ∼7-fold promotion in electron concentration with respect to its pristine counterpart. Benefiting from these, the semicrystalline sample exhibited dramatic enhancements in electron-involved photocatalytic processes, such as superoxide radical production and selective alcohol oxidation. This work brightens excitonic aspects for the design of advanced photocatalysts.