Hybrid Photocatalytic System Composed Of Plasmonic Nanometal And Butterfly Wing-structural Semiconductor Towards Enhanced Visible-to-near Infrared Solar Photocatalysis

How to efficiently produce clean new energy and how to control the pollution induced by energy production have turned into important issues to be solved.Photocatalysis is one of the best choice to tackle this problem.But at current stage,photocatalytic efficiency is still very low,which is caused by the inefficient use of the whole band of sunlight.This study first verifies the structural effects of four typical kinds of butterfly wing microstructures on enhancing UV-visible-near infrared light absorption through absorption spectrum measurement and optical simulation,followed by revealing the mechanism of absorption enhancement.Solar conversion to fuels or to electricity in semiconductors using far red-to-near infrared（NIR）light,which accounts for about 40%of solar energy,is highly significant.One main challenge is the development of novel strategies for activity promotion and new basic mechanisms for NIR response.Mother Nature has evolved to smartly capture far red-to-NIR light via their intelligent systems due to unique micro/nanoarchitectures,thus motivating us for biomimetic design.This study reports the first demonstration of a new strategy,based on adopting nature’s far red-to-NIR responsive architectures for an efficient bio-inspired photocatalytic system.The system is constructed by controlled assembly of light-harvesting plasmonic nanoantennas onto a typical photocatalytic unit with butterfly wings’3D micro/nanoarchitectures.Experiments and finite-difference time-domain（FDTD）simulations demonstrate the structural effects on obvious far red-to-NIR photocatalysis enhancement,which originates from（1）Enhancing far red-to-NIR（700¹200 nm）harvesting,up to 25%.（2）Enhancing electric-field amplitude of localized surface plasmon（LSPs）to more than 3.5 times than that of the non-structured one,which promotes the rate of electron-hole pair formation,thus substantially reinforcing photocatalysis.This proof-of-concept study provides a new methodology for NIR photocatalysis and would potentially guide future conceptually new NIR responsive system designs.Finally,this study used Lycaeides argyrognomon Bergstrasser wings as bio-templates to fabricate 3D hierarchical microstructural TiO₂ through atomic layer deposition for the sake of enhancing its light absorption ability.Plasmonic gold nanopyramids with broad-band visible-light absorption ability were fabricated and loaded on the as-prepared TiO₂ in order to obtain composite photocatalytic system responding to full-spectrum sunlight.Scanning electron microscope（SEM）,Transmission Electron Microscope（TEM）,ultraviolet-visible spectrophotometer,X-Ray Diffraction（XRD）were used for characterization.The measurement of carbon dioxide photoreduction indicates that with full-spectrum light illumination,the performance of gold nanopyramids-loaded butterfly wing-structural TiO₂ is54%higher than that of gold nanopyramids-loaded non-structural TiO₂.