Butterfly wing architecture assisted CdS/Au/TiO2 Z-scheme type photocatalytic water splitting

Abstract

Inspired by natural Z-scheme photosynthesis and black butterfly wing's antireflection morphology, we used the wings of butterfly Papilio nephelus Boisduva as templates to synthesize CdS/Au/TiO2 with butterfly wing architecture. This combination of artificial Z-scheme photosystem and butterfly wing's hierarchical architecture was expected to enhance the light harvesting and water splitting efficiency. The finite-difference time-domain (FDTD) simulation was applied to demonstrate the optical function of the architecture inherited from butterfly wing theoretically, UV–vis spectra and photocatalytic H2 evolution rates were further recorded to experimentally demonstrate the coupled effect of butterfly wing architecture and CdS/Au/TiO2 Z-scheme components. The FDTD simulation shows that the architecture of the wing scale TiO2 effectively reduced the UV light reflection by about 40%. Meanwhile, the wing scale architecture model exhibited lower UV reflection and transmission in water than those in air, which can be attributed to the stronger diffuse reflection in water. UV–vis spectra and photocatalytic H2 evolution experiments confirmed that the combination of the wing scale architecture and CdS/Au/TiO2 Z-scheme components contributed to the enhancement of the light harvesting ability and improved the water-splitting efficiency by 200% compared to the plate architecture TiO2. Inspired by Nature, we present a promising way for constructing efficient photocatalysts for hydrogen evolution.