Biomimetic fabrication of WO_3 for water splitting under visible light with high performance

摘要

Inspired by the high light-harvesting properties of typical butterfly wings, ceramic WO_3 butterfly wings with hierarchical structures of bio-butterfly wings was fabricated using a template of PapilioParis butterfly wings through a sol-gel method. The effect of calcination temperatures on the structures of the ceramic butterfly wings was investigated and the results showed that the WO_3 butterfly wing replica calcined at 550 C (WO _3 replica-550) is a single phase and has a high crystallinity and relatively fine hierarchical structure. The average grain size of WO_3 replica-550 and WO_3 powder are around 32.6 and 42.2 nm, respectively. Compared with pure WO_3 powder, WO_3 replica-550 demonstrated a higher light-harvesting capability in the region from 460 to 700 nm and more importantly the higher charge separation rate, as evidenced by electron paramagnetic resonance measurements. Photocatalytic O _2 evolutions from water were investigated on the ceramic butterfly wings and pure WO_3 powder under visible light (λ > 420 nm). The results showed that the amount of O_2 produced from WO _3 replica-550 is 50 higher than that of the pure WO_3 powder. The improved photocatalytic performance of WO_3 replica-550 is attributed to the quasi-honeycomb structure inherited from the PapilioParis butterfly wings, providing both high light-harvesting efficiency and efficient charge transport through the WO_3.