BiOCl Nanosheets Grown In Situ On 3D Hierarchical Structures Of Butterfly Wings For Enhanced Photocatalytic Activity Under Visible Light Irradiation

The building of artificial photosynthesis system with semiconductor photocatalyts for solar-to-chemical energy conversion process is one of the most effective ways against global energy crisis and air/water pollution.Bismuth oxyhalides?BiOX,X=Cl,Br and I?,a novel two-dimensional?2D?layered semiconductor,have drawn intensive attention for its special physicochemical property and band structure,high chemical and optical stability,nontoxicity,low cost,as well as corrosion resistance.Bismuth oxyhalides crystal is composed of[Bi₂O₂]layers sandwiched between two slabs of halogen ions[X].The difference between strong covalent bond of[Bi₂O₂]layers and weak Van der Waals force of[X]interlayers yields highly anisotropic features in structure,optical and electronic properties,etc.Therefore,bismuth oxyhalides show great potential in pollutant degradation,water splitting,CO₂ reduction,nitrogen fixation.However,bismuth oxyhalides still suffer from low solar light utilization rate and carrier separation efficiency,poor surface activity,difficult separation and recycle.The strategies for improving the photocatalytic activity of bismuth oxyhaides including element doping,surface plasmon resonance,heterojunction,defect engineering and three-dimensional?3D?microspheres,but their abilities in light absorption,recycle and so on are still need to be further enhanced for industrial application.In recently years,assembling 2D materials into spatially well-defined configurations in order to build practical,macroscopic devices with desirable functions becomes a hot research area.Researches show that natural species have developed and continue to develop delicate 3D structures to survive through natural selection,and these structures often display high absorption ability,but they are currently beyond our fabrication abilities either through a bottom-up self-organization method or a top-down photolithography process.Before decade,morphology genetic method was invented and has been the most common way to replicate the structure of natural species.Among these species,butterfly wings have characteristics of 3D hierarchical and open structures,great diversity and easy-to-raise which make them one of the most excellent choices as bio-template.In this work,we used butterfly wings with strong light capture capability as bio-templates and developed fabrication technique to grow wide-bandgap BiOCl nanosheets in situ on surface of butterfly wings for enhanced visible light photocatalytic performance.The main research contents as follows:?1?A novel fabrication route was designed to synthesis 3D BiOCl functional materials with sub-micrometer hierarchical structure of butterfly wings scales.BiOCl nanosheets could grow on the surface of scale through amino amplification treatment and electroless deposition.Lowering nucleation rate by releasing Cl^-slowly and guiding the growth of BiOCl nanosheets by pre-depositing BiOCl seeds could help to replicate nanosized rib structure.?2?The influence of hierarchical structure on visible light absorption and photocatalytic ability of BiOCl materials was investigated.Research results showed that butterfly wing improved the visible light capture ability of BiOCl.Compared with microspheres synthesized with same plating solution,the thickness of nanosheets grown on butterfly wing recuded to 10nm from30nm,and Rhodamine B?RhB?degradation rate improved to 87.3%from70.6%in 30min as well as to 97.9%from 81.4%in 40min under visible light irradiation.?3?Using the coupling effect of Au butterfly wing with incident light improve photocatalytic ability of BiOCl materials.Au butterfly wing could produce surface plasmon resonance and photo-Dember effect which improved the RhB degradation ability of BiOCl from 50.0%to 93.8%in20min and 70.6%to 98.1%in 30min under visible light irradiation.