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Silicon Quantum Dots Metal Enhanced Photoluminescence by Gold Nanoparticles in Colloidal Ensembles: Effect of Surface Coating
摘要： In the present study we report the photophysical properties of colloidal ensembles of silicon quantum dots (SiD) and gold nanoparticles (AuNP), particularly focused on investigating metal-enhanced photoluminescence effects. AuNP with different sizes, (27 ± 10) and (88 ± 12) nm, and ca. 3.4 nm size SiD with different surface groups, either covered with an oxidized surface film bearing Si-OH surface groups or grafted with propylamine leading to Si-(CH2)2-CH2-NH2 terminal functionalities, were tested to evaluate gold enhancement of SiD photoluminescence. Nanoparticles were characterized by HRTEM, FTIR, XPS, ICP-AES, and gel electrophoresis, while photophysical properties of nanoparticles alone and in colloidal ensembles at different concentrations were investigated by absorption and steady-state and time-resolved photoluminescence studies, including quantum yield determinations. Enhanced absorption and photoluminescence of SiD in the presence of AuNP was evidenced, leading in the most favorable cases to ca. 10-times increase in SiD brightness. This effect depends strongly on the SiD surface coating and its interaction with citrate-capped gold surfaces, where these interactions govern particles aggregation and relative distance distributions among SiD and AuNP in the ensembles. The nature of these interactions and how they affect metal-enhanced luminescence is thoroughly discussed. The present study provides significant information on the effect of SiD surface groups and surface charge on the metal-enhanced luminescence phenomenon in colloidal aqueous suspensions.
关键词： gold nanoparticles,colloidal ensembles,metal-enhanced photoluminescence,silicon quantum dots,surface coating
更新于2025-09-23 15:21:01
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Silver Electroless Finishing of Selective Laser Melting 3D-Printed AlSi10Mg Artifacts
摘要： Additive manufactured selective laser melting (AM-SLM) parts often need post-printing coatings. The current research presents a method for surface finishing of AM-SLM AlSi10Mg parts coated by electroless silver plating. Such coating can be applied as a decorative film on printed replicas of antique artifacts. For this purpose, silver was deposited for the first time on AlSi10Mg printed disk-shaped specimens and coins, making their appearance close to the original artifact. The silver was plated with and without adhesion-promoting silane self-assembled monolayers. Dimensions and mass measurements, pilling test, light microscopy, optical profilometer, SEM–EDS examination, XRD analysis, and FIB-SEM technique were applied to characterize the coated samples. The results displayed good silver quality with a satisfactory appearance. The roughness of the plated samples was slightly reduced as the thickness of the silver layer was increased. The developed coating can be adapted for different applications, including printed replicas of coins in museum exhibitions.
关键词： Surface coating,Selective laser melting,Additive manufacturing,AlSi10Mg alloy,Macro and microstructure,Electroless silver plating
更新于2025-09-16 10:30:52