Construction And Chatacterization Of Plasmonic Nanoarchitectured Hybrid System Towards Photocatalysis Applications

Surface plasmons are the collective oscillation of free electrons relative to ionic metal nuclei in metal nanostructures driven by the incident light,which induce many novel optical properties,including selective absorption and scattering of visible light,local field enhancement and subwavelength confinement of electromagnetic wave.Plasmonic photocatalysis makes use of plasmonic nanomaterials dispersed into semiconductor photocatalysts and possesses significant optical properties,which highly promotes the utilization of solar energy and enhances the efficiency of semiconductor photocatalysts.Plasmonic photocatalysis has recently facilitated the rapid progress in enhancing photocatalytic efficiency under visible light irradiation,increasing the prospect of using sunlight for environmental and energy applications such as wastewater treatment,air purification,water splitting and carbon dioxide reduction.However,there is still plenty of room for further physical,material and applied studies of plasmonic photocatalysis.In our opinion,several directions are worth further pursuing,including:a)new alternative plasmonic photocatalyst materials.Traditional plasmonic photocatalysts mostly involve noble metal as plasmonic component such as Au and Ag,which are highly cost and response only to visible region in common.b)efficient harvesting of solar light.The plasmonic photocatalysts can significantly improve the utilization of solar energy for semiconductor,while the absorption band ranges in hundreds nanometer limited by the dielctric function and nanostructure of plasmonic mateirials.In order to maximize the plasmonic effects in the semiconductor photocatalytic performance,the plasmonic materials are expected to provide good overlap between the LSPR absorption band and incident light.c)practical applications.Besides of the photocatalytic applications as mentioned above,more efficient applications on environment and energy issues are needed to be developed,such as surface self-cleaning and fixation of nitrogen(N₂)to ammonia(NH₃).On this account,our study is outlined as follows:1.Aiming at lowering the cost of photocatalysts materials and extend the absorption to near infrared(NIR),which accounts for 50% of solar energy,an alternative doped oxide plasmonic material,indium tin oxide(ITO)is firstly studied for its application in enhancing TiO₂ photocatalytic efficiency.It is verified of better performance in photocatalytic degradation.We also make full use of the good controllability of TiO₂ nanoarrays to modify the plasmonic property of ITO for photocatalysis by adjusting the thickness and size of ITO membrane.2.The materials are prepared by introducing ITO nanoparticles on a bundled nanowire array(BNWA)using a bottom-up self-assembly approach that combines anodization and electric-field-directed electrochemical etching.The ITO-BNWA plasmonic photocatalyst has broadband absorption with average absorption of 84% in the wavelength range between 400 and 2,500 nm and promoted the photocatalytic efficiency of degradation.3.We explore the application in recyclably surface-enhanced Raman scattering(SERS)substrates.We present a simple nanotechnique to fabricate gold-capped TiO₂ nanocomposites as robust,cost-efficient and recyclable SERS substrates.This technique has three distinct advantages.Three kinds of nanostructures(nanotube / nanolace / nanopore)can be prepared by adjusting TiO₂ anodization parameters,the substrate performance can be optimized by tailoring the plasmonic geometries and the Au-TiO₂ nanocomposites prove to be recyclable for SERS detection.4.The fixation of atmospheric N₂ to NH₃ is one of the most essential processes for sustaining life.Since the N?N bond in N₂ is one of the strongest bonds in chemistry,it remains a grand challenge to develop efficient catalysts for fixation of N₂ under ambient conditions.Plasmonic photocatalysis offers a great opportunity to improve the utilization of solar energy for N₂ fixation.Visible-light-assisted photocatalytic N₂ fixation is achieved by ligands functionalization which extend the light harvesting of the MOF to visible region.Furthermore,we construct Au/MOF plasmonic photocatalysts of N₂ fixation and the perfomance is highly improved.