Periodic noble metal nanoparticles offer a wide spectrum of applications including chemical and biological sensors,optical devices,and model catalysts due to their extraordinary properties.For sensing purposes and cat...Periodic noble metal nanoparticles offer a wide spectrum of applications including chemical and biological sensors,optical devices,and model catalysts due to their extraordinary properties.For sensing purposes and catalytic studies,substrates made of glass or fused-silica are normally required as supports,without the use of metallic adhesion layers.However,precise patterning of such uniform arrays of silica-supported noble metal nanoparticles,especially at sub-100 nm in diameter,is challenging without adhesion layers.In this paper,we report a robust method to large-scale fabricate highly ordered sub-20 nm noble metal nanoparticles,i.e.,gold and platinum,supported on silica substrates without adhesion layers,combining displacement Talbot lithography(DTL)with dry-etching techniques.Periodic photoresist nanocolumns at diameters of~110 nm are patterned on metal-coated oxidized silicon wafers using DTL,and subsequently transferred at a 1:1 ratio into anti-reflection layer coating(BARC)nanocolumns with the formation of nano-sharp tips,using nitrogen plasma etching.These BARC nanocolumns are then used as a mask for etching the deposited metal layer using inclined argon ion-beam etching.We find that increasing the etching time results in coneshaped silica features with metal nanoparticles on the tips at diameters ranging from 100 nm to sub-30 nm,over large areas of 3×3 cm^(2).Moreover,subsequent annealing these sub-30 nm metal nanoparticle arrays at high-temperature results in sub-20 nm metal nanoparticle arrays with~10^(10) uniform particles.展开更多
The particles of heterogeneous catalysts differ greatly in size,morphology,and most importantly,in activity.Studying these catalyst particles in batch typically results in ensemble averages,without any information at ...The particles of heterogeneous catalysts differ greatly in size,morphology,and most importantly,in activity.Studying these catalyst particles in batch typically results in ensemble averages,without any information at the level of individual catalyst particles.To date,the study of individual catalyst particles has been rewarding but is stll rather slow and often cumbersomel.Furthermore,these valuable in-depth studies at the single particle level lack statistical relevance.Here,we report the development of a droplet microreactor for high-throughput fluorescence-based measurements of the acidities of individual particles in fluid catalytic cracking(FCC)equilibrium catalysts(ECAT).This method combines systematic screening of single catalyst particles with statistical relevance.An oligomerization reaction of 4-methoxystyrene,catalyzed by the Bronsted acid sites inside the zeolite domains of the ECAT particles,Was performed on-chip at 95 ℃.The fluorescence signal generated by the reaction products inside the ECAT particles was detected near the outlet of the microreactor.The high-throughput acidity screening platform was capable of detecting~1000 catalyst particles at a rate of 1 catalyst particle every 2.4 s.The number of detected catalyst particles was representative of the overall catalyst particle population with a confidence level of 95%.The measured fluorescence intensities showed a clear acidity distribution among the catalyst particles,with the majority(96.1%)showing acidity levels belonging to old,deactivated catalyst particles and a minority(3.9%)exhibiting high acidity levels.The latter are potentially of high interest,as they reveal interesting new physicochemical properties indicating why the particles were still highly acidic and reactive.展开更多
The current progress of system miniaturization relies extensively on the development of 3D machining techniques to increase the areal structure density.In this work,a wafer-scale out-of-plane 3D silicon(Si)shaping tec...The current progress of system miniaturization relies extensively on the development of 3D machining techniques to increase the areal structure density.In this work,a wafer-scale out-of-plane 3D silicon(Si)shaping technology is reported,which combines a multistep plasma etching process with corner lithography.The multistep plasma etching procedure results in high aspect ratio structures with stacked semicircles etched deep into the sidewall and thereby introduces corners with a proper geometry for the subsequent corner lithography.Due to the geometrical contrast between the gaps and sidewall,residues are left only inside the gaps and form an inversion mask inside the semicircles.Using this mask,octahedra and donuts can be etched in a repeated manner into Si over the full wafer area,which demonstrates the potential of this technology for constructing high-density 3D structures with good dimensional control in the bulk of Si wafers.展开更多
基金This work was supported by the Netherlands Center for Multiscale Catalytic Energy Conversion(MCEC)。
文摘Periodic noble metal nanoparticles offer a wide spectrum of applications including chemical and biological sensors,optical devices,and model catalysts due to their extraordinary properties.For sensing purposes and catalytic studies,substrates made of glass or fused-silica are normally required as supports,without the use of metallic adhesion layers.However,precise patterning of such uniform arrays of silica-supported noble metal nanoparticles,especially at sub-100 nm in diameter,is challenging without adhesion layers.In this paper,we report a robust method to large-scale fabricate highly ordered sub-20 nm noble metal nanoparticles,i.e.,gold and platinum,supported on silica substrates without adhesion layers,combining displacement Talbot lithography(DTL)with dry-etching techniques.Periodic photoresist nanocolumns at diameters of~110 nm are patterned on metal-coated oxidized silicon wafers using DTL,and subsequently transferred at a 1:1 ratio into anti-reflection layer coating(BARC)nanocolumns with the formation of nano-sharp tips,using nitrogen plasma etching.These BARC nanocolumns are then used as a mask for etching the deposited metal layer using inclined argon ion-beam etching.We find that increasing the etching time results in coneshaped silica features with metal nanoparticles on the tips at diameters ranging from 100 nm to sub-30 nm,over large areas of 3×3 cm^(2).Moreover,subsequent annealing these sub-30 nm metal nanoparticle arrays at high-temperature results in sub-20 nm metal nanoparticle arrays with~10^(10) uniform particles.
基金supported by the Netherlands Center for Multiscale Catalytic Energy Conversion(MCEC),an NWO gravitation program funded by the Ministry of Education,Culture and Science of the government of the Netherlands.The authors would like to acknowledge Jan van Nieuwkasteele(University of Twente)for his invaluable help in setting up the Hamamatsu camera and attached computer,which enabled fast data processing for fluorescencedetection.
文摘The particles of heterogeneous catalysts differ greatly in size,morphology,and most importantly,in activity.Studying these catalyst particles in batch typically results in ensemble averages,without any information at the level of individual catalyst particles.To date,the study of individual catalyst particles has been rewarding but is stll rather slow and often cumbersomel.Furthermore,these valuable in-depth studies at the single particle level lack statistical relevance.Here,we report the development of a droplet microreactor for high-throughput fluorescence-based measurements of the acidities of individual particles in fluid catalytic cracking(FCC)equilibrium catalysts(ECAT).This method combines systematic screening of single catalyst particles with statistical relevance.An oligomerization reaction of 4-methoxystyrene,catalyzed by the Bronsted acid sites inside the zeolite domains of the ECAT particles,Was performed on-chip at 95 ℃.The fluorescence signal generated by the reaction products inside the ECAT particles was detected near the outlet of the microreactor.The high-throughput acidity screening platform was capable of detecting~1000 catalyst particles at a rate of 1 catalyst particle every 2.4 s.The number of detected catalyst particles was representative of the overall catalyst particle population with a confidence level of 95%.The measured fluorescence intensities showed a clear acidity distribution among the catalyst particles,with the majority(96.1%)showing acidity levels belonging to old,deactivated catalyst particles and a minority(3.9%)exhibiting high acidity levels.The latter are potentially of high interest,as they reveal interesting new physicochemical properties indicating why the particles were still highly acidic and reactive.
基金Financial support for this project was provided by the Foundation for Fundamental Research on Matter(FOM,Project 13CO12-1)which is part of The Netherlands Organization for Scientific Research(NWO).
文摘The current progress of system miniaturization relies extensively on the development of 3D machining techniques to increase the areal structure density.In this work,a wafer-scale out-of-plane 3D silicon(Si)shaping technology is reported,which combines a multistep plasma etching process with corner lithography.The multistep plasma etching procedure results in high aspect ratio structures with stacked semicircles etched deep into the sidewall and thereby introduces corners with a proper geometry for the subsequent corner lithography.Due to the geometrical contrast between the gaps and sidewall,residues are left only inside the gaps and form an inversion mask inside the semicircles.Using this mask,octahedra and donuts can be etched in a repeated manner into Si over the full wafer area,which demonstrates the potential of this technology for constructing high-density 3D structures with good dimensional control in the bulk of Si wafers.
