Flexible and thermally stable polyimide (PI) film containing hierarchical structure was synthesized as the substrate to support cuprous oxide for photocatalytic reduction of carbon dioxide. With the nanocasting technique, the structure on the leaves of Xanthosoma sagittifolium was duplicated on the surface of PI film. Followed by the ion-exchange process and adequate thermal-treatment, cuprous oxide nanoparticles were successfully immobilized on the artificial PI leaves and had the capability to photoreduce carbon dioxide. The biomimetic PI films obtained via two types of ion-exchange processes exhibited significant differences in UV-VIS absorption and in the depth distribution of cuprous oxide. With the selection of biomimetic structure, the hydrophobicity of the photocatalytic film was tunable that the photoreduction products were consequently varied. With the presence of hierarchical structure on the surface, the thermal stability of PI film was also enhanced. Therefore, the flexible photocatalytic film is a promising material for the application in the field requiring high mechanical and thermal stability, such as industrial flue-gas treatments.
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