Photocatalytic bioheteronanostructures by integrating multicomponent Cu2O–Au nanoparticles into ZnO-coated butterfly wings colored by photonic nanoarchitectures

Abstract

Complex biological photocatalytic heteronanostructures were produced by the integration of different multicomponent Au–Cu2O nanoparticles (NPs) into the blue-colored photonic nanoarchitectures occurring in the wings of male Polyommatus icarus butterflies. Both bare wings and wings conformally coated by 15-nm ZnO by atomic layer deposition were used as substrates. The NPs were characterized by UV–visible spectroscopy, focus stacking optical microscopy, and electron microscopy. After the deposition of the different NPs, the photocatalytic performance of the samples under visible light illumination was tested by the photodegradation of methyl orange in aqueous solution monitored continuously by an immersion probe. It was found that the components of the biological hetero-nanoarchitecture: ZnO-coated wings and wings without ZnO with deposited NPs exhibited poor catalytic performance. But the combined system: ZnO-coated wings with NPs deposited onto them exhibited sixfold to eightfold increase in their catalytic performance. This increase is attributed to the extension of the ZnO absorption into the visible range and to the formation of the heterojunction between the n-type ZnO and the p-type Cu2O NPs which resulted in the charge transfer of the photogenerated carriers. As the samples exhibited good stability under the continuous magnetic stirring, they can be used in flow-through systems suitable for wastewater remediation. The biological templates for the hetero-nanoarchitectures were produced by the controlled breeding of herbivorous insects, which does not raise any environmental concerns.