| Owing to their unique physical,chemical,optical,and electrical properties,Au and Ag nano materials have aroused the extensive interest of do mestic and foreign researchers.The macroscopic 2-dimensional（2D）Au/Ag nanofilms,fabricated using low dimensional Au and Ag nanomaterials as basic units,not only inherit the unique properties of low dimensional Au and Ag nanomaterials,such as high specific surface area,small size effect and quantum size effect,but also create so me co mprehensive properties,such as adjustable surface plasmon resonance coupling effect,electro magnetic field enhancement,photons capture capabilit y,electron transport capabilit y,and good stabilit y.Therefore,the 2D Au/Ag nano film bridges low dimensional Au and Ag nanomaterials and their macroscopic applications,widely used in the fields of energy catalysis,bio medicine,materials science,microelectronic devices and so on.The key factors that can tune the properties o f nano materials mainly include particle size,shape,co mposition,and surface atomic arrangement.Based on these understandings,this thesis mainly focused on the research of Au/Ag 2D nanofilms.By adjust ing the size,surface crystalline orientation,and co mposition,this thesis prepared nanoporous gold film（NPGFs）,Ag Nanowires（NWs）transparent conductor,and Ag@Au allo y ho llow NWs film and further explore their physicochemical properties and applications in energy devices.The main results achieved are out lined as follow:1.Light welding interfacially self-assembled Au nanoparticle（NP）film to fabricate large-area,high-purit y,and filament size-tunable NPGFs.This bottom-up method o f the thin film preparation allows tune the ligament and pore sizes,conduct ivit y,electrochemical surface area,and the number of exposed active sites of the resultant NPGFs just by changing the size of the start ing Au NPs,thereby optimizing the electrocatalyt ic activit y of the NPGFs.In the NPGFs,their cont inuous network provides efficient electron transport pathways,and meanwhile,the hyperbo lo id-like ligament structure formed during the light welding process makes the surface of NPGFs contain a large number o f high-energy active sites.The optimized 16 nm-NPGF shows excellent electrochemical act ivit y for methano l oxidat ion reaction（MOR）and H2O2 enzyme-free electrochemical sensing detect ion.2.Plasmon-enhanced MOR on NPGFs.This thesis used MOR as a model reaction and systemat ically studied the enhanced electrochemical catalysis fro m plasmon o f NPGFs.Upon plasmon excitation,its decay generates high-energy hot carriers in NPGFs.With the applying o f appropriate bias vo ltage,high-energy hot electrons are driven to the external circuit,generating observable photocurrent and effectively inhibit ing the recombination of hot electrons and hot ho les.The accumulat ion of hot ho les on the NPGFs surface downward removes the Fermi level relat ive to the equilibrium position,reducing the overpotential and activat ion energy of MOR and thus effect ively improving the oxidat ion capacit y of NPGFs to CH3OH.At the same t ime,the hot electrons could convert into heat through lattice co lliding,which enhances the transfer kinet ics o f the electrons during reaction with reduced overpotent ial.Therefore,the MOR activit y can be accelerated upon excitation o f the plasmon o f the NPGFs.As a result,the cyclic vo ltammogram curve showed a peak current densit y of 0.328 m A cm-2 at（0.2 V vs.SCE）for plasmon-enhanced MOR on NPGFs,which was 2.1 times o f that of normal MOR electrocatalysis with plasmon assistance.After po larizat ion at 0.2V for 3600 s,the steady current densit y o f plasmon-accelerated MOR is 4.9 times that of normal MOR.These results suggest that NPGFs show excellent photo-electrochemical act ivit y and stabilit y.3.Ligh welding enables the tuning of the surface crystalline orientat ion of NPGFs and in turn their electrochemical act ivit y.Citrate-stabilized Au NPs were used as the building blocks to prepare mono layer closely-packed Au NP thin films via the liquid/liquid interface self-assembly method.By controlling the duration of the light welding,this thesis prepared NPGFs with different ratios of crystalline facets and thus tunable electrocatalyt ic activit y.Upon light welding for 35 min and 80 min,the surface of NPGFs enriched a high proportion of{111}and{110}facets,respectively.In them,the NPGFs enriched with a high proportion o f{111}facets show higher electrocatalyt ic performance for MOR,while the NPGFs enriched with a high proportion of{110}facets show a better electrochemical sensing performance for glucose.4.Developing a new method for the synthesis of high-qualit y Ag NWs using mixed PVP（including linear chain PVP and branched chain PVP）hydrogel instead of commercial PVP as capping agent and stabilizer.The improved synthesis method is highly adaptable to the product ion process and equipment of the tradit ional po lyo l reduction method,and can produce high-quality Ag NWs with high aspect ratio（～1200）,negligible byproducts（Ag NPs）,and ultrathin capping layer（～1 nm）.The resultant Ag NWs can be direct ly processed into high-quality Ag NW conductor without addit ional separation and posttreatment processes,thereby greatly reducing the fabricat ion t ime and coat.Compared with the single-carrier device constructed fro m Ag NW thin film prepared from tradit ionally PVP-wrapped Ag NWs,the counter device constructed fro m the Ag NW thin film prepared fro m current ly synthesized Ag NWs show a better current collect ion performance,with its current collection efficiency improved by 7.7 times.5.Synthesizing plasmonic blackbody of Ag@Au allo y nanostructures for efficient so lar evaporation of water.Ag and Au nanostructures have high chemical stabilit y,and their SPR peak location could be extended from visible to near-infrared region via adjust ing its structure and composit ion,thereby enabling efficient broadband light absorption.Based on this theory,this thesis constructed a plasmonic blackbody o f Ag@Au allo y hollow porous nanostructure using Ag NWs as a template,fo llowed by deposition of Au NPs on the template via galvanic replacement reaction.The Ag@Au allo y nano material with hollow porous nanostructure can efficiently capture light because multiple light scatterings greatly extend the path length of incident light.In addition,the strong plasmon coupling among surface Au NPs themselves and between Au NPs and hollow porous allo y nanowires results in broadband and efficient absorption from visible to near-infrared region.The as-prepared Ag@Au allo y ho llow porous nanowires were deposited on a po lypropylene film using vacuum filtration,forming a plasmonic blackbody film which can float on water as an interfacial photothermal convertor for high-performance solar steam generation. |
