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Articles 1 - 30 of 464

Full-Text Articles in Nanoscience and Nanotechnology

Synthesis And Optical Properties Of Ordered-Vacancy Perovskite Cesium Bismuth Halide Nanocrystals, Rainie D. Nelson, Kalyan Santra, Y. Wang, Atefe Hadi, Jacob W. Petrich, Matthew G. Panthani Aug 2019

Synthesis And Optical Properties Of Ordered-Vacancy Perovskite Cesium Bismuth Halide Nanocrystals, Rainie D. Nelson, Kalyan Santra, Y. Wang, Atefe Hadi, Jacob W. Petrich, Matthew G. Panthani

Matthew Panthani

Perovskite-phase cesium bismuth halide (Cs3Bi2X9; X = Cl, Br, I) nanocrystals were synthesized using a hot-injection approach. These nanocrystals adopted ordered-vacancy perovskite crystal structures and demonstrated composition-tunable optical properties. Growth occurred by initial formation of Bi0 seeds, and morphology was controlled by precursor and seed concentration. The Cs3Bi2I9 nanocrystals demonstrated excellent stability under ambient conditions for several months. Contrary to previous reports, we find that photoluminescence originates from the precursor material as opposed to the Cs3Bi2X9 nanocrystals.


Ambient Synthesis Of Nanomaterials By In Situ Heterogeneous Metal/Ligand Reactions, Boyce S. Chang, Brijith Thomas, Jiahao Chen, Ian D. Tevis, Paul Karanja, Simge Çınar, Amrit Venkatesh, Aaron Rossini, Martin M. Thuo Aug 2019

Ambient Synthesis Of Nanomaterials By In Situ Heterogeneous Metal/Ligand Reactions, Boyce S. Chang, Brijith Thomas, Jiahao Chen, Ian D. Tevis, Paul Karanja, Simge Çınar, Amrit Venkatesh, Aaron Rossini, Martin M. Thuo

Martin M. Thuo

Coordination polymers are ideal synthons in creating high aspect ratio nanostructures, however, conventional synthetic methods are often restricted to batch-wise and costly processes. Herein, we demonstrate a non-traditional, frugal approach to synthesize 1D coordination polymers by in situ etching of zerovalent metal particle precursors. This procedure is denoted as the heterogeneous metal/ligand reaction and was demonstrated on Group 13 metals as a proof of concept. Simple carboxylic acids supply the etchant protons and ligands for metal ions (conjugate base) in a 1 : 1 ratio. This scalable reaction produces a 1D polymer that assembles into high-aspect ratio ‘nanobeams’. We demonstrate ...


Ambient Synthesis Of Nanomaterials By In Situ Heterogeneous Metal/Ligand Reactions, Boyce S. Chang, Brijith Thomas, Jiahao Chen, Ian D. Tevis, Paul Karanja, Simge Çınar, Amrit Venkatesh, Aaron Rossini, Martin M. Thuo Aug 2019

Ambient Synthesis Of Nanomaterials By In Situ Heterogeneous Metal/Ligand Reactions, Boyce S. Chang, Brijith Thomas, Jiahao Chen, Ian D. Tevis, Paul Karanja, Simge Çınar, Amrit Venkatesh, Aaron Rossini, Martin M. Thuo

Aaron Rossini

Coordination polymers are ideal synthons in creating high aspect ratio nanostructures, however, conventional synthetic methods are often restricted to batch-wise and costly processes. Herein, we demonstrate a non-traditional, frugal approach to synthesize 1D coordination polymers by in situ etching of zerovalent metal particle precursors. This procedure is denoted as the heterogeneous metal/ligand reaction and was demonstrated on Group 13 metals as a proof of concept. Simple carboxylic acids supply the etchant protons and ligands for metal ions (conjugate base) in a 1 : 1 ratio. This scalable reaction produces a 1D polymer that assembles into high-aspect ratio ‘nanobeams’. We demonstrate ...


Fabrication Of High-Resolution Graphene-Based Flexible Electronics Via Polymer Casting, Metin Uz, Kyle Jackson, Maxsam S. Donta, Juhyung Jung, Matthew T. Lentner, John A. Hondred, Jonathan C. Claussen, Surya K. Mallapragada Jul 2019

Fabrication Of High-Resolution Graphene-Based Flexible Electronics Via Polymer Casting, Metin Uz, Kyle Jackson, Maxsam S. Donta, Juhyung Jung, Matthew T. Lentner, John A. Hondred, Jonathan C. Claussen, Surya K. Mallapragada

Jonathan C. Claussen

In this study, a novel method based on the transfer of graphene patterns from a rigid or flexible substrate onto a polymeric film surface via solvent casting was developed. The method involves the creation of predetermined graphene patterns on the substrate, casting a polymer solution, and directly transferring the graphene patterns from the substrate to the surface of the target polymer film via a peeling-off method. The feature sizes of the graphene patterns on the final film can vary from a few micrometers (as low as 5 µm) to few millimeters range. This process, applied at room temperature, eliminates the ...


Fabrication Of High-Resolution Graphene-Based Flexible Electronics Via Polymer Casting, Metin Uz, Kyle Jackson, Maxsam S. Donta, Juhyung Jung, Matthew T. Lentner, John A. Hondred, Jonathan C. Claussen, Surya K. Mallapragada Jul 2019

Fabrication Of High-Resolution Graphene-Based Flexible Electronics Via Polymer Casting, Metin Uz, Kyle Jackson, Maxsam S. Donta, Juhyung Jung, Matthew T. Lentner, John A. Hondred, Jonathan C. Claussen, Surya K. Mallapragada

Surya K. Mallapragada

In this study, a novel method based on the transfer of graphene patterns from a rigid or flexible substrate onto a polymeric film surface via solvent casting was developed. The method involves the creation of predetermined graphene patterns on the substrate, casting a polymer solution, and directly transferring the graphene patterns from the substrate to the surface of the target polymer film via a peeling-off method. The feature sizes of the graphene patterns on the final film can vary from a few micrometers (as low as 5 µm) to few millimeters range. This process, applied at room temperature, eliminates the ...


Stamped Multilayer Graphene Laminates For Disposable In-Field Electrodes: Application To Electrochemical Sensing Of Hydrogen Peroxide And Glucose, Loreen R. Stromberg, John A. Hondred, Delaney Sanborn, Deyny Mendivelso-Perez, Srikanthan Ramesh, Iris V. Rivero, Josh Kogot, Emily Smith, Carmen Gomes, Jonathan C. Claussen Jul 2019

Stamped Multilayer Graphene Laminates For Disposable In-Field Electrodes: Application To Electrochemical Sensing Of Hydrogen Peroxide And Glucose, Loreen R. Stromberg, John A. Hondred, Delaney Sanborn, Deyny Mendivelso-Perez, Srikanthan Ramesh, Iris V. Rivero, Josh Kogot, Emily Smith, Carmen Gomes, Jonathan C. Claussen

Carmen Gomes

A multi-step approach is described for the fabrication of multi-layer graphene-based electrodes without the need for ink binders or post-print annealing. Graphite and nanoplatelet graphene were chemically exfoliated using a modified Hummers’ method and the dried material was thermally expanded. Expanded materials were used in a 3D printed mold and stamp to create laminate electrodes on various substrates. The laminates were examined for potential sensing applications using model systems of peroxide (H2O2) and enzymatic glucose detection. Within the context of these two assay systems, platinum nanoparticle electrodeposition and oxygen plasma treatment were examined as methods for improving sensitivity. Electrodes made ...


Stamped Multilayer Graphene Laminates For Disposable In-Field Electrodes: Application To Electrochemical Sensing Of Hydrogen Peroxide And Glucose, Loreen R. Stromberg, John A. Hondred, Delaney Sanborn, Deyny Mendivelso-Perez, Srikanthan Ramesh, Iris V. Rivero, Josh Kogot, Emily Smith, Carmen Gomes, Jonathan C. Claussen Jul 2019

Stamped Multilayer Graphene Laminates For Disposable In-Field Electrodes: Application To Electrochemical Sensing Of Hydrogen Peroxide And Glucose, Loreen R. Stromberg, John A. Hondred, Delaney Sanborn, Deyny Mendivelso-Perez, Srikanthan Ramesh, Iris V. Rivero, Josh Kogot, Emily Smith, Carmen Gomes, Jonathan C. Claussen

Jonathan C. Claussen

A multi-step approach is described for the fabrication of multi-layer graphene-based electrodes without the need for ink binders or post-print annealing. Graphite and nanoplatelet graphene were chemically exfoliated using a modified Hummers’ method and the dried material was thermally expanded. Expanded materials were used in a 3D printed mold and stamp to create laminate electrodes on various substrates. The laminates were examined for potential sensing applications using model systems of peroxide (H2O2) and enzymatic glucose detection. Within the context of these two assay systems, platinum nanoparticle electrodeposition and oxygen plasma treatment were examined as methods for improving sensitivity. Electrodes made ...


Stamped Multilayer Graphene Laminates For Disposable In-Field Electrodes: Application To Electrochemical Sensing Of Hydrogen Peroxide And Glucose, Loreen R. Stromberg, John A. Hondred, Delaney Sanborn, Deyny Mendivelso-Perez, Srikanthan Ramesh, Iris V. Rivero, Josh Kogot, Emily Smith, Carmen Gomes, Jonathan C. Claussen Jul 2019

Stamped Multilayer Graphene Laminates For Disposable In-Field Electrodes: Application To Electrochemical Sensing Of Hydrogen Peroxide And Glucose, Loreen R. Stromberg, John A. Hondred, Delaney Sanborn, Deyny Mendivelso-Perez, Srikanthan Ramesh, Iris V. Rivero, Josh Kogot, Emily Smith, Carmen Gomes, Jonathan C. Claussen

Emily Smith

A multi-step approach is described for the fabrication of multi-layer graphene-based electrodes without the need for ink binders or post-print annealing. Graphite and nanoplatelet graphene were chemically exfoliated using a modified Hummers’ method and the dried material was thermally expanded. Expanded materials were used in a 3D printed mold and stamp to create laminate electrodes on various substrates. The laminates were examined for potential sensing applications using model systems of peroxide (H2O2) and enzymatic glucose detection. Within the context of these two assay systems, platinum nanoparticle electrodeposition and oxygen plasma treatment were examined as methods for improving sensitivity. Electrodes made ...


Thin Biobased Transparent Uv-Blocking Coating Enabled By Nanoparticle Self-Assembly, Emily Olson, Yifan Li, Fang-Yi Lin, Ana Miller, Fei Liu, Ayuna Tsyrenova, Devin Palm, Greg W. Curtzwiler, Keith L. Vorst, Eric W. Cochran, Shan Jiang Jun 2019

Thin Biobased Transparent Uv-Blocking Coating Enabled By Nanoparticle Self-Assembly, Emily Olson, Yifan Li, Fang-Yi Lin, Ana Miller, Fei Liu, Ayuna Tsyrenova, Devin Palm, Greg W. Curtzwiler, Keith L. Vorst, Eric W. Cochran, Shan Jiang

Eric W. Cochran

A waterborne, UV-blocking, and visually transparent nanocomposite coating was formulated with ZnO nanoparticles and 2-hydroxyethyl cellulose (HEC). The coating is highly effective (< 5% UV and ~ 65% visible transmittance) and the film thickness (0.2 – 2.5 μm) is ~100 times thinner than the conventional coatings of similar UV-blocking performance. The superior properties are due to the fractal structures of ZnO nanoparticles assembled within the HEC matrix, revealed by scanning electron microscopy (SEM) and small-angle x-ray scattering (SAXS). Changing the binder to 2-hydroxyethyl starch (HES) diminishes the UV-blocking performance, as ZnO nanoparticles form dense globular aggregates, with an aggregation number measured by SAXS three orders of magnitude larger than the HEC coating. Since HEC and HES share the same same chemical compositionrepeating glucose unit in the polymer backbone, it suggests that the conformational characteristics of the binder polymer have a strong influence on the nanoparticle aggregation, which plays a key role in determining the optical performance. Similar structures were achieved with TiO2 nanoparticles. This study not only offers a cost-effective and readily scalable method to fabricate transparent UV-blocking coating, but also demonstrates that the unique fractal aggregation structures in a nanocomposite material can provide high performance and functionality without fully dispersing the nanoparticles.


Porous Wood Monoliths Decorated With Platinum Nano-Urchins As Catalysts For Underwater Micro-Vehicle Propulsion Via H2o2 Decomposition, Bolin Chen, Ahmed Gsalla, Anand Gaur, Yu Hui Lui, Xiaohui Tang, Jason Geder, Marius Pruessner, Brian J. Melde, Igor L. Medintz, Behrouz Shafei, Shan Hu, Jonathan C. Claussen Jun 2019

Porous Wood Monoliths Decorated With Platinum Nano-Urchins As Catalysts For Underwater Micro-Vehicle Propulsion Via H2o2 Decomposition, Bolin Chen, Ahmed Gsalla, Anand Gaur, Yu Hui Lui, Xiaohui Tang, Jason Geder, Marius Pruessner, Brian J. Melde, Igor L. Medintz, Behrouz Shafei, Shan Hu, Jonathan C. Claussen

Jonathan C. Claussen

Porous carbon is becoming an important and promising high-surface area scaffold material for various energy-based applications including catalysis. Here we demonstrate the growth of urchin-like platinum nanoparticles (PtNPs) on carbon monoliths derived from basswood that work as catalysts for micro underwater vehicle (MUV) propulsion via H2O2 decomposition. The carbon monoliths were constructed of natural basswood that was carbonized in argon (Ar) and subjected to a subsequent CO2 activation process that rendered the material into a hardened 3D porous activated carbonized wood (ACW) with inner channel voids measuring 10-70 μm in diameter. The PtNP nanourchins (500 nm or less in total ...


Porous Wood Monoliths Decorated With Platinum Nano-Urchins As Catalysts For Underwater Micro-Vehicle Propulsion Via H2o2 Decomposition, Bolin Chen, Ahmed Gsalla, Anand Gaur, Yu Hui Lui, Xiaohui Tang, Jason Geder, Marius Pruessner, Brian J. Melde, Igor L. Medintz, Behrouz Shafei, Shan Hu, Jonathan C. Claussen Jun 2019

Porous Wood Monoliths Decorated With Platinum Nano-Urchins As Catalysts For Underwater Micro-Vehicle Propulsion Via H2o2 Decomposition, Bolin Chen, Ahmed Gsalla, Anand Gaur, Yu Hui Lui, Xiaohui Tang, Jason Geder, Marius Pruessner, Brian J. Melde, Igor L. Medintz, Behrouz Shafei, Shan Hu, Jonathan C. Claussen

Shan Hu

Porous carbon is becoming an important and promising high-surface area scaffold material for various energy-based applications including catalysis. Here we demonstrate the growth of urchin-like platinum nanoparticles (PtNPs) on carbon monoliths derived from basswood that work as catalysts for micro underwater vehicle (MUV) propulsion via H2O2 decomposition. The carbon monoliths were constructed of natural basswood that was carbonized in argon (Ar) and subjected to a subsequent CO2 activation process that rendered the material into a hardened 3D porous activated carbonized wood (ACW) with inner channel voids measuring 10-70 μm in diameter. The PtNP nanourchins (500 nm or less in total ...


Transparent Ohmic Contacts For Solution-Processed, Ultrathin Cdte Solar Cells, J. Matthew Kurley, Matthew G. Panthani, Ryan W. Crisp, Sanjini U. Nanayakkara, Gregory F. Pach, Matthew O. Reese, Margaret H. Hudson, Dmitriy S. Dolzhnikov, Vadim Tanygin, Joseph M. Luther, Dmitri V. Talapin Jun 2019

Transparent Ohmic Contacts For Solution-Processed, Ultrathin Cdte Solar Cells, J. Matthew Kurley, Matthew G. Panthani, Ryan W. Crisp, Sanjini U. Nanayakkara, Gregory F. Pach, Matthew O. Reese, Margaret H. Hudson, Dmitriy S. Dolzhnikov, Vadim Tanygin, Joseph M. Luther, Dmitri V. Talapin

Matthew Panthani

Recently, solution-processing became a viable route for depositing CdTe for use in photovoltaics. Ultrathin (∼500 nm) solar cells have been made using colloidal CdTe nanocrystals with efficiencies exceeding 12% power conversion efficiency (PCE) demonstrated by using very simple device stacks. Further progress requires an effective method for extracting charge carriers generated during light harvesting. Here, we explored solution-based methods for creating transparent Ohmic contacts to the solution-deposited CdTe absorber layer and demonstrated molecular and nanocrystal approaches to Ohmic hole-extracting contacts at the ITO/CdTe interface. We used scanning Kelvin probe microscopy to further show how the above approaches improved carrier ...


Synthesis Of Germanium Nanocrystals From Solid-State Disproportionation Of A Chloride-Derived Germania Glass, Yujie Wang, Utkarsh Ramesh, Charles K. A. Nyamekye, Bradley J. Ryan, Rainie D. Nelson, Abdulla M. Alebri, Umar H. Hamdeh, Atefe Hadi, Emily A. Smith, Matthew G. Panthani Jun 2019

Synthesis Of Germanium Nanocrystals From Solid-State Disproportionation Of A Chloride-Derived Germania Glass, Yujie Wang, Utkarsh Ramesh, Charles K. A. Nyamekye, Bradley J. Ryan, Rainie D. Nelson, Abdulla M. Alebri, Umar H. Hamdeh, Atefe Hadi, Emily A. Smith, Matthew G. Panthani

Matthew Panthani

Germanium nanocrystals (Ge NCs) have potential to be used in several optoelectronic applications such as photodetectors and light-emitting diodes. Here, we report a solid-state route to synthesizing Ge NCs through thermal disproportionation of a germania (GeOX) glass, which was synthesized by hydrolyzing a GeCl2·dioxane complex. The GeOX glass synthesized in this manner was found to have residual Cl content. The process of nanocrystal nucleation and growth was monitored using powder X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. Compared to existing solid-state routes for synthesizing colloidal Ge NCs, this approach requires fewer steps and is amenable ...


Synthesis Of Germanium Nanocrystals From Solid-State Disproportionation Of A Chloride-Derived Germania Glass, Yujie Wang, Utkarsh Ramesh, Charles K. A. Nyamekye, Bradley J. Ryan, Rainie D. Nelson, Abdulla M. Alebri, Umar H. Hamdeh, Atefe Hadi, Emily A. Smith, Matthew G. Panthani Jun 2019

Synthesis Of Germanium Nanocrystals From Solid-State Disproportionation Of A Chloride-Derived Germania Glass, Yujie Wang, Utkarsh Ramesh, Charles K. A. Nyamekye, Bradley J. Ryan, Rainie D. Nelson, Abdulla M. Alebri, Umar H. Hamdeh, Atefe Hadi, Emily A. Smith, Matthew G. Panthani

Emily Smith

Germanium nanocrystals (Ge NCs) have potential to be used in several optoelectronic applications such as photodetectors and light-emitting diodes. Here, we report a solid-state route to synthesizing Ge NCs through thermal disproportionation of a germania (GeOX) glass, which was synthesized by hydrolyzing a GeCl2·dioxane complex. The GeOX glass synthesized in this manner was found to have residual Cl content. The process of nanocrystal nucleation and growth was monitored using powder X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. Compared to existing solid-state routes for synthesizing colloidal Ge NCs, this approach requires fewer steps and is amenable ...


Reshaping, Intermixing, And Coarsening For Metallic Nanocrystals: Nonequilibrium Statistical Mechanical And Coarse-Grained Modeling, King C. Lai, Yong Han, Peter M. Spurgeon, Wenyu Huang, Patricia A. Thiel, Da-Jiang Liu, James W. Evans Jun 2019

Reshaping, Intermixing, And Coarsening For Metallic Nanocrystals: Nonequilibrium Statistical Mechanical And Coarse-Grained Modeling, King C. Lai, Yong Han, Peter M. Spurgeon, Wenyu Huang, Patricia A. Thiel, Da-Jiang Liu, James W. Evans

James W. Evans

Self-assembly of supported 2D or 3D nanocrystals (NCs) by vacuum deposition and of 3D NCs by solution-phase synthesis (with possible subsequent transfer to a support) produces intrinsically nonequilibrium systems. Individual NCs can have far-from-equilibrium shapes and composition profiles. The free energy of NC ensembles is lowered by coarsening which can involve Ostwald ripening or Smoluchowski ripening (NC diffusion and coalescence). Preservation of individual NC structure and inhibition of coarsening are key, e.g., for avoiding catalyst degradation. This review focuses on postsynthesis evolution of metallic NCs. Atomistic-level modeling typically utilizes stochastic lattice-gas models to access appropriate time and length scales ...


Reshaping, Intermixing, And Coarsening For Metallic Nanocrystals: Nonequilibrium Statistical Mechanical And Coarse-Grained Modeling, King C. Lai, Yong Han, Peter M. Spurgeon, Wenyu Huang, Patricia A. Thiel, Da-Jiang Liu, James W. Evans Jun 2019

Reshaping, Intermixing, And Coarsening For Metallic Nanocrystals: Nonequilibrium Statistical Mechanical And Coarse-Grained Modeling, King C. Lai, Yong Han, Peter M. Spurgeon, Wenyu Huang, Patricia A. Thiel, Da-Jiang Liu, James W. Evans

Wenyu Huang

Self-assembly of supported 2D or 3D nanocrystals (NCs) by vacuum deposition and of 3D NCs by solution-phase synthesis (with possible subsequent transfer to a support) produces intrinsically nonequilibrium systems. Individual NCs can have far-from-equilibrium shapes and composition profiles. The free energy of NC ensembles is lowered by coarsening which can involve Ostwald ripening or Smoluchowski ripening (NC diffusion and coalescence). Preservation of individual NC structure and inhibition of coarsening are key, e.g., for avoiding catalyst degradation. This review focuses on postsynthesis evolution of metallic NCs. Atomistic-level modeling typically utilizes stochastic lattice-gas models to access appropriate time and length scales ...


Reshaping, Intermixing, And Coarsening For Metallic Nanocrystals: Nonequilibrium Statistical Mechanical And Coarse-Grained Modeling, King C. Lai, Yong Han, Peter M. Spurgeon, Wenyu Huang, Patricia A. Thiel, Da-Jiang Liu, James W. Evans Jun 2019

Reshaping, Intermixing, And Coarsening For Metallic Nanocrystals: Nonequilibrium Statistical Mechanical And Coarse-Grained Modeling, King C. Lai, Yong Han, Peter M. Spurgeon, Wenyu Huang, Patricia A. Thiel, Da-Jiang Liu, James W. Evans

Patricia A. Thiel

Self-assembly of supported 2D or 3D nanocrystals (NCs) by vacuum deposition and of 3D NCs by solution-phase synthesis (with possible subsequent transfer to a support) produces intrinsically nonequilibrium systems. Individual NCs can have far-from-equilibrium shapes and composition profiles. The free energy of NC ensembles is lowered by coarsening which can involve Ostwald ripening or Smoluchowski ripening (NC diffusion and coalescence). Preservation of individual NC structure and inhibition of coarsening are key, e.g., for avoiding catalyst degradation. This review focuses on postsynthesis evolution of metallic NCs. Atomistic-level modeling typically utilizes stochastic lattice-gas models to access appropriate time and length scales ...


Structure And High Performance Of Lead-Free (K0.5na0.5)Nbo3 Piezoelectric Nanofibers With Surface-Induced Crystallization At Lowered Temperature, Yasmin Mohamed Yousry, Kui Tao, Xiaoli Tan, Ayman Mahmoud Mohamed, Yumei Wang, Shuting Chen, Seeram Ramakrishna Jun 2019

Structure And High Performance Of Lead-Free (K0.5na0.5)Nbo3 Piezoelectric Nanofibers With Surface-Induced Crystallization At Lowered Temperature, Yasmin Mohamed Yousry, Kui Tao, Xiaoli Tan, Ayman Mahmoud Mohamed, Yumei Wang, Shuting Chen, Seeram Ramakrishna

Xiaoli Tan

Lead-free potassium and sodium niobate (KNN) nanofiber webs with random and aligned configurations were prepared by electrospinning process from polymer-modified chemical solution. The crystallization process, structure, composition, dielectric, ferroelectric and piezoelectric properties of the nanofibers and nanofiber webs were investigated. Theoretical analysis and experimental results showed that the surface-induced heterogeneous nucleation resulted in the remarkable lower crystallization temperature for the KNN nanofibers with {100} orientation of the perovskite phase in contrast to the bulk KNN gel, and thus well-controlled chemical stoichiometry. Low dielectric loss, large electric polarization, and high piezoelectric performance were obtained in the nanofiber webs. In particular, the ...


Squeezed Nanocrystals: Equilibrium Configuration Of Metal Clusters Embedded Beneath The Surface Of A Layered Material, Scott E. Julien, Ann Lii-Rosales, Kai-Tak Wan, Yong Han, Michael C. Tringides, James W. Evans, Patricia A. Thiel Mar 2019

Squeezed Nanocrystals: Equilibrium Configuration Of Metal Clusters Embedded Beneath The Surface Of A Layered Material, Scott E. Julien, Ann Lii-Rosales, Kai-Tak Wan, Yong Han, Michael C. Tringides, James W. Evans, Patricia A. Thiel

Patricia A. Thiel

Shapes of functional metallic nanocrystals, typically synthesized either free in solution or supported on surfaces, are key for controlling properties. Here, we consider a novel new class of metallic nanocrystals, copper islands embedded near the surface of graphite, which can be considered a model system for metals embedded beneath surfaces of layered materials, or beneath supported membranes. We develop a continuum elasticity (CE) model for the equilibrium shape of these islands, and compare its predictions with experimental data. The CE model incorporates appropriate surface energy, adhesion energies, and strain energy. The agreement between the CE model and the data is ...


Quantifying Thermal Boundary Conductance Of 2d–3d Interfaces, Zlatan Aksamija, Cameron J. Foss Feb 2019

Quantifying Thermal Boundary Conductance Of 2d–3d Interfaces, Zlatan Aksamija, Cameron J. Foss

Zlatan Aksamija

Heat dissipation in next-generation electronics based on two-dimensional (2D) materials is a
critical issue in their development and implementation. A potential bottleneck for heat removal in
2D-based devices is the thermal pathway from the 2D layer into its supporting substrate. The choice
of substrate, its composition and structure, can strongly impact the thermal boundary conductance
(TBC). Here we investigate the temperature-dependent TBC of 42 interfaces formed between a
group of six 2D materials and seven crystalline and amorphous substrates. We use first-principles
density functional perturbation theory to calculate the full phonon dispersion of the 2D layers and
substrates and then ...


Enhanced Electrochemical Biosensor And Supercapacitor With 3d Porous Architectured Graphene Via Salt Impregnated Inkjet Maskless Lithography, John A. Hondred, Igor L. Medintz, Jonathan C. Claussen Feb 2019

Enhanced Electrochemical Biosensor And Supercapacitor With 3d Porous Architectured Graphene Via Salt Impregnated Inkjet Maskless Lithography, John A. Hondred, Igor L. Medintz, Jonathan C. Claussen

Jonathan C. Claussen

Advances in solution-phase graphene patterning has provided a facile route for rapid, low-cost and scalable manufacturing of electrochemical devices, even on flexible substrates. While graphene possesses advantageous electrochemical properties of high surface area and fast heterogenous charge transport, these properties are attributed to the edge planes and defect sites, not the basal plane. Herein, we demonstrate enhancement of the electroactive nature of patterned solution-phase graphene by increasing the porosity and edge planes through the construction of a multidimensional architecture via salt impregnated inkjet maskless lithography (SIIML) and CO2 laser annealing. Various sized macroscale pores (<25 to ∼250 μm) are patterned directly in the graphene surface by incorporating porogens (i.e., salt crystals) in the ...


Application Of Scanning Angle Raman Spectroscopy For Determining The Location Of Buried Polymer Interfaces With Tens Of Nanometer Precision, Craig A. Damin, Vy H.T. Nguyen, Auguste S. Niyibizi, Emily A. Smith Dec 2018

Application Of Scanning Angle Raman Spectroscopy For Determining The Location Of Buried Polymer Interfaces With Tens Of Nanometer Precision, Craig A. Damin, Vy H.T. Nguyen, Auguste S. Niyibizi, Emily A. Smith

Emily Smith

Near-infrared scanning angle (SA) Raman spectroscopy was utilized to determine the interface location in bilayer films (a stack of two polymer layers) of polystyrene (PS) and polycarbonate (PC). Finite-difference-time-domain (FDTD) calculations of the sum square electric field (SSEF) for films with total bilayer thicknesses of 1200–3600 nm were used to construct models for simultaneously measuring the film thickness and the location of the buried interface between the PS and PC layers. Samples with total thicknesses of 1320, 1890, 2300, and 2750 nm and varying PS/PC interface locations were analyzed using SA Raman spectroscopy. Comparing SA Raman spectroscopy and ...


Building Materials From Colloidal Nanocrystal Assemblies: Molecular Control Of Solid/Solid Interfaces In Nanostructured Tetragonal Zro2, Santosh Shaw, Tiago F. Silva, Jonathan M. Bobbitt, Fabian Naab, Cleber L. Rodrigues, Bin Yuan, Julia J. Chang, Xinchun Tian, Emily A. Smith, Ludovico Cademartiri Dec 2018

Building Materials From Colloidal Nanocrystal Assemblies: Molecular Control Of Solid/Solid Interfaces In Nanostructured Tetragonal Zro2, Santosh Shaw, Tiago F. Silva, Jonathan M. Bobbitt, Fabian Naab, Cleber L. Rodrigues, Bin Yuan, Julia J. Chang, Xinchun Tian, Emily A. Smith, Ludovico Cademartiri

Emily Smith

We here describe a bottom-up approach to control the composition of solid/solid interfaces in nanostructured materials, and we test its effectiveness on tetragonal ZrO2, an inorganic phase of great technological significance. Colloidal nanocrystals capped with trioctylphosphine oxide (TOPO) or oleic acid (OA) are deposited, and the organic fraction of the ligands is selectively etched with O2 plasma. The interfaces in the resulting all-inorganic colloidal nanocrystal assemblies are either nearly bare (for OA-capped nanocrystals) or terminated with phosphate groups (for TOPO-capped nanocrystals) resulting from the reaction of phosphine oxide groups with plasma species. The chemical modification of the interfaces has ...


Impact Of Substrate And Process On The Electrical Performance Of Screen-Printed Nickel Electrodes: Fundamental Mechanism Of Ink Film Roughness, Bilge N. Altay, Jerome Jourdan, Vikram S. Turkani, Hervé Dietsch, Dinesh Maddipatla, Alexandra Pekarovicova, Paul D. Fleming, Massood Atashbar Nov 2018

Impact Of Substrate And Process On The Electrical Performance Of Screen-Printed Nickel Electrodes: Fundamental Mechanism Of Ink Film Roughness, Bilge N. Altay, Jerome Jourdan, Vikram S. Turkani, Hervé Dietsch, Dinesh Maddipatla, Alexandra Pekarovicova, Paul D. Fleming, Massood Atashbar

Bilge Nazli Altay

In recent years, traditional printing methods have been integrated to print flexible electronic devices and circuits. Since process requirements for electronics diff er from those for graphic printing, the fundamentals require rediscovery mainly to optimize manufacturing techniques and to find cost reduction methods without compromising functional performance. In addition, alternative inks need to be formulated to increase the variety of functional inks and to pioneer new product developments. In this report, we investigate a thermoplastic-based nickel ink prototype to print electrodes using a screen-printing process. Process fundamentals are explored, and cost reduction methods are addressed by studying ...


Synthesis Of Graphene Nanosheets Through Spontaneous Sodiation Process, Deepak-George Thomas, Emrah Kavak, Niloofar Hashemi, Reza Montazami, Nicole N. Hashemi Nov 2018

Synthesis Of Graphene Nanosheets Through Spontaneous Sodiation Process, Deepak-George Thomas, Emrah Kavak, Niloofar Hashemi, Reza Montazami, Nicole N. Hashemi

Nicole N. Hashemi

Graphene is one of the emerging materials in the nanotechnology industry due to its potential applications in diverse areas. We report the fabrication of graphene nanosheets by spontaneous electrochemical reaction using solvated ion intercalation into graphite. The current literature focuses on the fabrication of graphene using lithium metal. Our procedure uses sodium metal, which results in a reduction of costs. Using various characterization techniques, we confirmed the fabrication of graphene nanosheets. We obtained an intensity ratio (ID/IG) of 0.32 using Raman spectroscopy, interlayer spacing of 0.39 nm and our XPS results indicate that our fabricated compound is ...


Flexible Laser-Induced Graphene For Nitrogen Sensing In Soil, Nate T. Garland, Eric S. Mclamore, Nicholas D. Cavallaro, Deyny Mendivelso-Perez, Emily A. Smith, Dapeng Jing, Jonathan C. Claussen Oct 2018

Flexible Laser-Induced Graphene For Nitrogen Sensing In Soil, Nate T. Garland, Eric S. Mclamore, Nicholas D. Cavallaro, Deyny Mendivelso-Perez, Emily A. Smith, Dapeng Jing, Jonathan C. Claussen

Jonathan C. Claussen

Flexible graphene electronics are rapidly gaining interest, but their widespread implementation has been impeded by challenges with ink preparation, ink printing, and post-print annealing processes. Laser-induced graphene (LIG) promises a facile alternative by creating flexible graphene electronics on polyimide substrates through a one-step laser writing fabrication method. Herein we demonstrate the use of LIG, created through a low-cost UV laser, for electrochemical ion selective sensing of plant-available nitrogen (i.e., both ammonium and nitrate ions: NH4+ and NO3-) in soil samples. The laser used to create the LIG was operated at distinct pulse rates (10, 20, 30, 40, and 50 ...


Photophysical Properties Of Wavelength-Tunable Methylammonium Lead Halide Perovskite Nanocrystals, Daniel J. Freppon, Long Men, Sadie J. Burkhow, Jacob W. Petrich, Javier Vela, Emily A. Smith Jul 2018

Photophysical Properties Of Wavelength-Tunable Methylammonium Lead Halide Perovskite Nanocrystals, Daniel J. Freppon, Long Men, Sadie J. Burkhow, Jacob W. Petrich, Javier Vela, Emily A. Smith

Emily Smith

We present the time-correlated luminescence of isolated nanocrystals of five methylammonium lead mixed-halide perovskite compositions (CH3NH3PbBr3−xIx) that were synthesized with varying iodide and bromide anion loading. All analyzed nanocrystals had a spherical morphology with diameters in the range of 2 to 32 nm. The luminescence maxima of CH3NH3PbBr3−xIx nanocrystals were tuned to wavelengths ranging between 498 and 740 nm by varying the halide loading. Both CH3NH3PbI3 and CH3NH3PbBr3 nanocrystals exhibited no luminescence intermittency for more than 90% of the 250 s analysis time, as defined by a luminescence intensity three standard deviations above the background. The mixed halide ...


Calcination Does Not Remove All Carbon From Colloidal Nanocrystal Assemblies, Pratyasha Mohapatra, Santosh Shaw, Deyny Mendivelso-Perez, Jonathan M. Bobbitt, Tiago F. Silva, Fabian Naab, Bin Yuan, Xinchun Tian, Emily A. Smith, Ludovico Cademartiri Jul 2018

Calcination Does Not Remove All Carbon From Colloidal Nanocrystal Assemblies, Pratyasha Mohapatra, Santosh Shaw, Deyny Mendivelso-Perez, Jonathan M. Bobbitt, Tiago F. Silva, Fabian Naab, Bin Yuan, Xinchun Tian, Emily A. Smith, Ludovico Cademartiri

Emily Smith

Removing organics from hybrid nanostructures is a crucial step in many bottom-up materials fabrication approaches. It is usually assumed that calcination is an effective solution to this problem, especially for thin films. This assumption has led to its application in thousands of papers. We here show that this general assumption is incorrect by using a relevant and highly controlled model system consisting of thin films of ligand-capped ZrO2 nanocrystals. After calcination at 800 °C for 12 h, while Raman spectroscopy fails to detect the ligands after calcination, elastic backscattering spectrometry characterization demonstrates that ~18% of the original carbon atoms are ...


Large-Scale Synthesis Of Colloidal Si Nanocrystals And Their Helium Plasma Processing Into Spin-On, Carbon-Free Nanocrystalline Si Films, Pratyasha Mohapatra, Deyny Mendivelso-Perez, Jonathan M. Bobbitt, Santosh Shaw, Bin Yuan, Xinchun Tian, Emily A. Smith, Ludovico Cademartiri Jul 2018

Large-Scale Synthesis Of Colloidal Si Nanocrystals And Their Helium Plasma Processing Into Spin-On, Carbon-Free Nanocrystalline Si Films, Pratyasha Mohapatra, Deyny Mendivelso-Perez, Jonathan M. Bobbitt, Santosh Shaw, Bin Yuan, Xinchun Tian, Emily A. Smith, Ludovico Cademartiri

Emily Smith

This paper describes a simple approach to the large-scale synthesis of colloidal Si nanocrystals and their processing into spin-on carbon-free nanocrystalline Si films. The synthesized silicon nanoparticles are capped with decene, dispersed in hexane, and deposited on silicon substrates. The deposited films are exposed to nonoxidizing room-temperature He plasma to remove the organic ligands without adversely affecting the silicon nanoparticles to form crack-free thin films. We further show that the reactive ion etching rate in these films is 1.87 times faster than that for single-crystalline Si, consistent with a simple geometric argument that accounts for the nanoscale roughness caused ...


Dynamical Thermal Conductivity Of Suspended Graphene Ribbons In The Hydrodynamic Regime, Zlatan Aksamija, Arnab K. Majee Jul 2018

Dynamical Thermal Conductivity Of Suspended Graphene Ribbons In The Hydrodynamic Regime, Zlatan Aksamija, Arnab K. Majee

Zlatan Aksamija

The steady-state behavior of thermal transport in bulk and nanostructured semiconductors has been widely
studied, both theoretically and experimentally. On the other hand, fast transients and frequency dynamics of
thermal conduction has been given less attention. The frequency response of thermal conductivity has become
more crucial in recent years, especially in light of the constant rise in the clock frequencies in microprocessors
and terahertz sensing applications. Thermal conductivity in response to a time-varying temperature field starts
decaying when the frequency exceeds a cutoff frequency Omega_c, which is related to the inverse of phonon relaxation time τ, on the order of ...