451 results on '"Ralph G. Nuzzo"'
Search Results
2. Refractive index sensing and surface-enhanced Raman spectroscopy using silver–gold layered bimetallic plasmonic crystals
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Somi Kang, Sean E. Lehman, Matthew V. Schulmerich, An-Phong Le, Tae-woo Lee, Stephen K. Gray, Rohit Bhargava, and Ralph G. Nuzzo
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finite-difference time-domain ,nanoimprint soft lithography ,plasmonics ,surface plasmon resonance ,Technology ,Chemical technology ,TP1-1185 ,Science ,Physics ,QC1-999 - Abstract
Herein we describe the fabrication and characterization of Ag and Au bimetallic plasmonic crystals as a system that exhibits improved capabilities for quantitative, bulk refractive index (RI) sensing and surface-enhanced Raman spectroscopy (SERS) as compared to monometallic plasmonic crystals of similar form. The sensing optics, which are bimetallic plasmonic crystals consisting of sequential nanoscale layers of Ag coated by Au, are chemically stable and useful for quantitative, multispectral, refractive index and spectroscopic chemical sensing. Compared to previously reported homometallic devices, the results presented herein illustrate improvements in performance that stem from the distinctive plasmonic features and strong localized electric fields produced by the Ag and Au layers, which are optimized in terms of metal thickness and geometric features. Finite-difference time-domain (FDTD) simulations theoretically verify the nature of the multimode plasmonic resonances generated by the devices and allow for a better understanding of the enhancements in multispectral refractive index and SERS-based sensing. Taken together, these results demonstrate a robust and potentially useful new platform for chemical/spectroscopic sensing.
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- 2017
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3. Inorganic Materials and Assembly Techniques for Flexible and Stretchable Electronics.
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Junwen He, Ralph G. Nuzzo, and John A. Rogers
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- 2015
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4. Aliovalent Doping of CeO2 Improves the Stability of Atomically Dispersed Pt
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Haodong Wang, Ralph G. Nuzzo, Matthew Kottwitz, Nebojsa Marinkovic, Yuanyuan Li, Sanjaya D. Senanayake, Anatoly I. Frenkel, and Ning Rui
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Materials science ,Chemical engineering ,Dopant ,Atom ,Doping ,Infrared spectroscopy ,General Materials Science ,Thermal stability ,Absorption (chemistry) ,Oxygen vacancy ,Catalysis - Abstract
Atomically dispersed supported catalysts hold considerable promise as catalytic materials. The ability to employ and stabilize them against aggregation in complex process environments remains a key challenge to the elusive goal of 100% atom utilization in catalysis. Herein, using a Gd-doped ceria support for atomically dispersed surface Pt atoms, we establish how the combined effects of aliovalent doping and oxygen vacancy generation provide dynamic mechanisms that serve to enhance the stability of supported single-atom configurations. Using correlated, in situ X-ray absorption, photoelectron, and vibrational spectroscopy methods for the analysis of samples on the two types of support (with and without Gd doping), we establish that the Pt atoms are located proximal to Gd dopants, forming a speciation that serves to enhance the thermal stability of Pt atoms against aggregation.
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- 2021
5. Single Atom Catalysts: A Review of Characterization Methods
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Matthew Kottwitz, Yuanyuan Li, Anatoly I. Frenkel, Haodong Wang, and Ralph G. Nuzzo
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Crystallography ,Materials science ,Characterization methods ,Atom (order theory) ,Structure property ,General Medicine ,Characterization (materials science) ,Catalysis - Published
- 2021
6. Photovoltaic Thermal Management in Luminescent Solar Concentrators
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Megan E. Phelan, David R. Needell, Maggie M. Potter, Haley C. Bauser, Catherine N. Ryczek, Ralph G. Nuzzo, and Harry A. Atwater
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- 2022
7. Nanoclusters
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Yuanyuan Li, John J. Rehr, Ralph G. Nuzzo, and Anatoly I. Frenkel
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- 2022
8. Energy Storage Mechanisms in High-Capacity Graphitic C3N4 Cathodes for Al-Ion Batteries
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Ralph G. Nuzzo, Andrew A. Gewirth, Matthew Kottwitz, Chengsi Pan, Deyu Liu, Ruixian Zhang, and Minjeong Shin
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Materials science ,High capacity ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Cathode ,Energy storage ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Anode ,law.invention ,Ion ,General Energy ,law ,Physical and Theoretical Chemistry ,0210 nano-technology - Abstract
Al-ion batteries are a promising alternative to lithium-ion batteries because of the unique advantages of the Al anode, such as low cost and high specific capacities. Cathodes developed for these b...
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- 2020
9. Biomimetic and Biologically Compliant Soft Architectures via 3D and 4D Assembly Methods: A Perspective
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Jay M. Taylor, Haiwen Luan, Jennifer A. Lewis, John A. Rogers, Ralph G. Nuzzo, and Paul V. Braun
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Mechanics of Materials ,Biomimetics ,Mechanical Engineering ,Printing, Three-Dimensional ,General Materials Science - Abstract
Recent progress in soft material chemistry and enabling methods of 3D and 4D fabrication-emerging programmable material designs and associated assembly methods for the construction of complex functional structures-is highlighted. The underlying advances in this science allow the creation of soft material architectures with properties and shapes that programmably vary with time. The ability to control composition from the molecular to the macroscale is highlighted-most notably through examples that focus on biomimetic and biologically compliant soft materials. Such advances, when coupled with the ability to program material structure and properties across multiple scales via microfabrication, 3D printing, or other assembly techniques, give rise to responsive (4D) architectures. The challenges and prospects for progress in this emerging field in terms of its capacities for integrating chemistry, form, and function are described in the context of exemplary soft material systems demonstrating important but heretofore difficult-to-realize biomimetic and biologically compliant behaviors.
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- 2022
10. Silicon Heterojunction Microcells
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Megan Phelan, David R. Needell, Cora M. Went, Pradeep Balaji, Harry A. Atwater, Maggie M. Potter, Rebecca Glaudell, Andre Augusto, Michael J. Enright, Ralph G. Nuzzo, Haley Bauser, and Phillip Jahelka
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Materials science ,Fabrication ,Passivation ,Laser cutting ,business.industry ,Optoelectronics ,Microcell ,General Materials Science ,Wafer ,Dry etching ,business ,Microscale chemistry ,Microfabrication - Abstract
We report the design, fabrication, and characterization of silicon heterojunction microcells, a new type of photovoltaic cell that leverages high-efficiency bulk wafers in a microscale form factor, while also addressing the challenge of passivating microcell sidewalls to mitigate carrier recombination. We present synthesis methods exploiting either dry etching or laser cutting to realize microcells with native oxide-based edge passivation. Measured microcell performance for both fabrication processes is compared to that in simulations. We characterize the dependence of microcell open-circuit voltage (V_(oc)) on the cell area–perimeter ratio and examine synthesis processes that affect edge passivation quality, such as sidewall damage removal, the passivation material, and the deposition technique. We report the highest Si microcell V_(oc) to date (588 mV, for a 400 μm × 400 μm × 80 μm device), demonstrate V_(oc) improvements with deposited edge passivation of up to 55 mV, and outline a pathway to achieve microcell efficiencies surpassing 15% for such device sizes.
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- 2021
11. Fabrication techniques for high-performance Si heterojunction (SHJ) microcells
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Megan Phelan, Rebecca Glaudell, Maggie M. Potter, Michael J. Enright, Pradeep Balaji, Ralph G. Nuzzo, Phil R. Jahelka, Andre Augusto, Haley Bauser, David R. Needell, and Harry A. Atwater
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Fabrication ,Materials science ,business.industry ,Photovoltaic system ,Semiconductor device modeling ,Deep reactive-ion etching ,Optoelectronics ,Microcell ,Heterojunction ,Wafer ,Wafer dicing ,business - Abstract
Silicon heterojunction (SHJ) microcells offer a promising photovoltaic (PV) device for a wide range of micro-electronic applications due to their high performance potential. We examine two separate techniques for dicing SHJ microcells from bulk wafers: deep reactive ion etching (DRIE) and micro-laser cutting. We present the challenges and optimizations for each technique, as well as microcell performance for a 400µm x 400µm x 80µm microcell. Given the thickness of silicon wafers and the low face-to-edge area ratio for SHJ microcells of these dimensions, we consider varied illumination conditions for this structure. SHJ microcells are able to absorb photons along all surfaces; as such, we study microcell performance at each edge interface. We examine both modeled and experimental data of microcells across various lighting conditions and present high-performances for both sets of measurements.
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- 2021
12. Outdoor performance of a tandem InGaP/Si photovoltaic luminescent solar concentrator
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Paul Stradins, Hanxiao Su, David R. Needell, A. Paul Alivisatos, Zach Nett, Megan Phelan, Ognjen Ilic, Colton R. Bukowsky, San Theingi, John F. Geisz, Haley Bauser, Ralph G. Nuzzo, Michael G. Deceglie, Harry A. Atwater, and Brent A. Koscher
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Fabrication ,Materials science ,Tandem ,Renewable Energy, Sustainability and the Environment ,business.industry ,Photovoltaic system ,Luminescent solar concentrator ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Thermal diffusivity ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,law.invention ,Quantum dot ,law ,Optoelectronics ,sense organs ,Thin film ,0210 nano-technology ,business ,Waveguide - Abstract
We report the design, fabrication and outdoor characterization of a tandem luminescent solar concentrator/Si multi-junction photovoltaic module. Our tandem LSC/Si device consists of an InGaP LSC functioning as a top cell and a passivated contact Si bottom cell. The LSC comprises of an InGaP microcell array coupled to a polymer waveguide, loaded with CdSe/CdS core-shell quantum dot luminophores. The light trapping efficiency of the LSC waveguide is enhanced by encapsulation with photoluminescence trapping mirrors consisting of dielectric multilayer thin films. We demonstrate the performance of the LSC/Si device through a series of outdoor tests under various irradiance conditions conducted at the National Renewable Energy Laboratory. We report the first outdoor testing data of an LSC/Si tandem module, displaying maintained performance across varied diffusivity conditions for the LSC component. Finally, we model the tandem module performance using a ray optic simulation-based multiphysics model and forecast a pathway for high efficiency tandem LSC/Si module performance.
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- 2021
13. Local Structure and Electronic State of Atomically Dispersed Pt Supported on Nanosized CeO2
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Janis Timoshenko, Mahalingam Balasubramanian, Ralph G. Nuzzo, Guangjin Wang, Sanjaya D. Senanayake, Robert M. Palomino, Qin Wu, Anatoly I. Frenkel, Zongyuan Liu, Yuanyuan Li, Jiahao Huang, Matthew Kottwitz, and Deyu Lu
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inorganic chemicals ,Materials science ,010405 organic chemistry ,chemistry.chemical_element ,Nanotechnology ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Chemical reaction ,Electron spectroscopy ,Local structure ,Catalysis ,0104 chemical sciences ,chemistry ,Atom ,Selectivity ,Platinum ,Sol-gel - Abstract
Single atom catalysts (SACs) have shown high activity and selectivity in a growing number of chemical reactions. Many efforts aimed at unveiling the structure-property relationships underpinning th ...
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- 2019
14. CoS2 as a Sulfur Redox-Active Cathode Material for High-Capacity Nonaqueous Zn Batteries
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Ralph G. Nuzzo, Andrew A. Gewirth, Chengsi Pan, and Ruixian Zhang
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Materials science ,chemistry.chemical_element ,High capacity ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Sulfur ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,General Energy ,chemistry ,Chemical engineering ,Cathode material ,Redox active ,Physical and Theoretical Chemistry ,0210 nano-technology - Abstract
Nonaqueous Zn-ion batteries are a promising candidate for a high-energy storage system to replace Li-ion batteries. Here, we report on CoS2 as a cathode material for Zn-ion batteries using nonaqueo...
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- 2019
15. High capacity 3D structured tin-based electroplated Li-ion battery anodes
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Sanghyeon Kim, Jerome Davis, Hailong Ning, Zhelong Jiang, Pengcheng Sun, Ralph G. Nuzzo, Paul V. Braun, Feifei Fan, Luoxia Cao, Jinyun Liu, and John B. Cook
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Battery (electricity) ,Materials science ,Renewable Energy, Sustainability and the Environment ,Energy Engineering and Power Technology ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Cathode ,Lithium-ion battery ,0104 chemical sciences ,law.invention ,Ion ,Anode ,chemistry ,law ,Electrode ,General Materials Science ,Composite material ,0210 nano-technology ,Electroplating ,Tin - Abstract
3D structured porous electrodes have been considered as a possible solution for accommodating the volume change of alloying lithium ion battery anode materials during cycling. However, lab-scale porous electrodes tend to be thin, and the loading of the activity materials is also small, the combination of which results in electrodes with impractically low areal and volumetric capacities. Here, we develop a high areal and volumetric capacity 3D-structured Sn/C anode by using a two steps electroplating process. An electrode with a 20%v/v Sn loading exhibits a high volumetric/areal capacity of ∼879 mA h/cm3/6.59 mA h/cm2 after 100 cycles at 0.5 C and a good rate performance of about 750 mA h/cm3 and 5.5 mA h/cm2 (delithiation) at 10 C in a half-cell configuration. The 3D Sn/C anode also shows good compatibility with a commercial LCO cathode in a full cell configuration.
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- 2019
16. Understanding the Effect of Interlayers at the Thiophosphate Solid Electrolyte/Lithium Interface for All-Solid-State Li Batteries
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Kimberly L. Bassett, Matthias J. Young, Jeffrey W. Elam, Lingzi Sang, Vinayak P. Dravid, Fernando C. Castro, Andrew A. Gewirth, Richard T. Haasch, Ralph G. Nuzzo, and Lin X. Chen
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Battery (electricity) ,Materials science ,General Chemical Engineering ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,Electrolyte ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,01 natural sciences ,Decomposition ,0104 chemical sciences ,Thiophosphate ,chemistry.chemical_compound ,Dendrite (crystal) ,chemistry ,Chemical engineering ,Materials Chemistry ,Lithium ,0210 nano-technology ,Electrical impedance - Abstract
All-solid-state Li-ion batteries afford possibilities to enhance battery safety while improving their energy and power densities. Current challenges for achieving high-performance all-solid-state batteries with long cycle life include shorting resulting predominantly from Li dendrite formation and infiltration through the solid electrolyte (SE) and increases in cell impedance induced by SE decomposition at the SE/electrode interface. In this work, we evaluate the electrochemical properties of two interlayer materials, Si and LixAl(2–x/3)O3 (LiAlO), at the Li7P3S11 (LPS)/Li interface. Compared to the Li/LPS/Li symmetric cells in absence of interlayers, the presence of Si and LiAlO both significantly enhance the cycle number and total charge passing through the interface before failures resulting from cell shorting. In both cases, the noted improvements were accompanied by cell impedances that had increased substantially. The data reveal that both interlayers prevent the direct exposure of LPS to the metall...
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- 2018
17. Dynamic structure of active sites in ceria-supported Pt catalysts for the water gas shift reaction
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Anatoly I. Frenkel, Matthew Kottwitz, Joshua L. Vincent, Michael J. Enright, Lihua Zhang, Wei-Chang Yang, Ralph G. Nuzzo, Peter A. Crozier, Yuanyuan Li, Jiahao Huang, Zongyuan Liu, and Sanjaya D. Senanayake
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Catalytic transformation ,Active structure ,Hydrogen ,Science ,General Physics and Astronomy ,chemistry.chemical_element ,engineering.material ,010402 general chemistry ,01 natural sciences ,General Biochemistry, Genetics and Molecular Biology ,Water-gas shift reaction ,Article ,Catalysis ,Chemical engineering ,High activity ,Heterogeneous catalysis ,Multidisciplinary ,010405 organic chemistry ,General Chemistry ,0104 chemical sciences ,chemistry ,Chemical physics ,engineering ,Nanoparticles ,Noble metal ,Selectivity - Abstract
Oxide-supported noble metal catalysts have been extensively studied for decades for the water gas shift (WGS) reaction, a catalytic transformation central to a host of large volume processes that variously utilize or produce hydrogen. There remains considerable uncertainty as to how the specific features of the active metal-support interfacial bonding—perhaps most importantly the temporal dynamic changes occurring therein—serve to enable high activity and selectivity. Here we report the dynamic characteristics of a Pt/CeO2 system at the atomic level for the WGS reaction and specifically reveal the synergistic effects of metal-support bonding at the perimeter region. We find that the perimeter Pt0 − O vacancy−Ce3+ sites are formed in the active structure, transformed at working temperatures and their appearance regulates the adsorbate behaviors. We find that the dynamic nature of this site is a key mechanistic step for the WGS reaction., Revealing the structure and dynamics of active sites is essential to understand catalytic mechanisms. Here the authors demonstrate the dynamic nature of perimeter Pt0−O vacancy−Ce3+ sites in Pt/CeO2 and the key effects of their dynamics on the mechanism of the water gas shift reaction.
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- 2021
18. Biocompliant Composite Au/pHEMA Plasmonic Scaffolds for 3D Cell Culture and Noninvasive Sensing of Cellular Metabolites
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Sean E. Lehman, Sanjaya Jayalath, Joselle M. McCracken, Ralph G. Nuzzo, and Lou Ann Miller
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Scaffold ,Molecular diffusion ,Materials science ,Composite number ,Biomedical Engineering ,Cell Culture Techniques ,Pharmaceutical Science ,Metal Nanoparticles ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Spectrum Analysis, Raman ,01 natural sciences ,0104 chemical sciences ,Biomaterials ,3D cell culture ,Colloidal gold ,Gold ,Biomimetics ,0210 nano-technology ,Biosensor ,Plasmon ,Polyhydroxyethyl Methacrylate - Abstract
The field of 3D printing is an area of active research, with a substantial focus given to the design and construction of customized tools for applications in technology. There exists a particular need in these developing areas of opportunity for new multi-functional soft materials that are biologically compatible for the growth and directed culturing of cells. Herein, a composite material consisting of gold nanoparticles with useful plasmonic properties embedded within a highly hydrophilic poly-2-hydroxyethylmethacrylate matrix is described and characterized. This composite material serves dual functions as both host framework scaffold for cell lines such as pre-osteoblasts as well as a plasmonic biosensor for in situ measurements of living cells. The plasmonic properties of this system are characterized as a function of the material properties and related to compositional features of the material through a proposed light-directed mechanism. This chemistry provides a tunable, 3D printable plasmonic composite material of encapsulated gold nanoparticles in a biologically-compliant, acrylate-based hydrogel matrix. Surface-enhanced Raman scattering studies of 3D-microcultures supported by the scaffolds are carried out and the strong influence of perm-selective molecular diffusion in its analytical responses is established. Most notably, specific, largely hydrophilic, cellular metabolites are detected within the supported live cultures.
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- 2020
19. Autonomous Light Management in Flexible Photoelectrochromic Films Integrating High Performance Silicon Solar Microcells
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Bruno G. Nicolau, Sean E. Lehman, Aaron Petronico, Maggie M. Potter, Mikayla A. Yoder, Junwen He, Ralph G. Nuzzo, Harry A. Atwater, Michael J. Enright, and Megan Phelan
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Silicon ,Computer science ,business.industry ,Automotive industry ,Energy Engineering and Power Technology ,chemistry.chemical_element ,Electrochromic devices ,External source ,Engineering physics ,chemistry ,Electrochromism ,Photovoltaics ,Light management ,Materials Chemistry ,Electrochemistry ,Chemical Engineering (miscellaneous) ,Electrical and Electronic Engineering ,business ,Heat management - Abstract
Commercial smart window technologies for dynamic light and heat management in building and automotive environments traditionally rely on electrochromic (EC) materials powered by an external source. This design complicates building-scale installation requirements and substantially increases costs for applications in retrofit construction. Self-powered photoelectrochromic (PEC) windows are an intuitive alternative wherein a photovoltaic (PV) material is used to power the electrochromic device, which modulates the transmission of the incident solar flux. The PV component in this application must be sufficiently transparent and produce enough power to efficiently modulate the EC device transmission. Here, we propose Si solar microcells (μ-cells) that are i) small enough to be visually transparent to the eye, and ii) thin enough to enable flexible PEC devices. Visual transparency is achieved when Si μ-cells are arranged in high pitch (i.e. low-integration density) form factors while maintaining the advantages of a single-crystalline PV material (i.e., long lifetime and high performance). Additionally, the thin dimensions of these Si μ-cells enable fabrication on flexible substrates to realize these flexible PEC devices. The current work demonstrates this concept using WO₃ as the EC material and V₂O₅ as the ion storage layer, where each component is fabricated via sol-gel methods that afford improved prospects for scalability and tunability in comparison to thermal evaporation methods. The EC devices display fast switching times, as low as 8 seconds, with a modulation in transmission as high as 33%. Integration with two Si μ-cells in series (affording a 1.12 V output) demonstrates an integrated PEC module design with switching times of less than 3 minutes, and a modulation in transmission of 32% with an unprecedented EC:PV areal ratio.
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- 2020
20. Semiconductor Nanomembrane Materials for High-Performance Soft Electronic Devices
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Ralph G. Nuzzo, Mikayla A. Yoder, John A. Rogers, Zheng Yan, and Mengdi Han
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Flexibility (engineering) ,Chemistry ,business.industry ,Semiconductor materials ,Nanotechnology ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Biochemistry ,Catalysis ,0104 chemical sciences ,Phosphorene ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,Semiconductor ,Nano ,Electronics ,0210 nano-technology ,business - Abstract
The development of methods to synthesize and physically manipulate extremely thin, single-crystalline inorganic semiconductor materials, so-called nanomembranes, has led to an almost explosive growth of research worldwide into uniquely enabled opportunities for their use in new "soft" and other unconventional form factors for high-performance electronics. The unique properties that nanomembranes afford, such as their flexibility and lightweight characteristics, allow them to be integrated into electronic and optoelectronic devices that, in turn, adopt these unique attributes. For example, nanomembrane devices are able to make conformal contact to curvilinear surfaces and manipulate strain to induce the self-assembly of various 3D nano/micro device architectures. Further, thin semiconductor materials (e.g., Si-nanomembranes, transition metal dichalcogenides, and phosphorene) are subject to the impacts of quantum and other size-dependent effects that in turn enable the manipulation of their bandgaps and the properties of electronic and optoelectronic devices fabricated from them. In this Perspective, nanomembrane synthesis techniques and exemplary applications of their use are examined. We specifically describe nanomembrane chemistry exploiting high-performance materials, along with precise/high-throughput techniques for their manipulation that exemplify their growing capacities to shape outcomes in technology. Prominent challenges in the chemistry of these materials are presented along with future directions that might guide the development of next generation nanomembrane-based devices.
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- 2018
21. Solid–Liquid Lithium Electrolyte Nanocomposites Derived from Porous Molecular Cages
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Bruno G. Nicolau, Jeffrey S. Moore, Ralph G. Nuzzo, Andrew A. Gewirth, Aaron Petronico, and Timothy P. Moneypenny
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Solid-state chemistry ,Nanocomposite ,Chemistry ,Composite number ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,Electrolyte ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Biochemistry ,Catalysis ,0104 chemical sciences ,Ion ,Colloid and Surface Chemistry ,Chemical engineering ,Ionic conductivity ,Lithium ,0210 nano-technology ,Porosity - Abstract
We demonstrate that solid–liquid nanocomposites derived from porous organic cages are effective lithium ion electrolytes at room temperature. A solid–liquid electrolyte nanocomposite (SLEN) fabricated from a LiTFSI/DME electrolyte system and a porous organic cage exhibits ionic conductivity on the order of 1 × 10–3 S cm–1. With an experimentally measured activation barrier of 0.16 eV, this composite is characterized as a superionic conductor. Furthermore, the SLEN displays excellent oxidative stability up to 4.7 V vs Li/Li+. This simple three-component system enables the rational design of electrolytes from tunable discrete molecular architectures.
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- 2018
22. Identifying Dynamic Structural Changes of Active Sites in Pt–Ni Bimetallic Catalysts Using Multimodal Approaches
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Olga V. Safonova, Daniel Grolimund, Ralph G. Nuzzo, Yuanyuan Li, Anatoly I. Frenkel, Binhang Yan, Deyu Liu, Siyu Yao, Eric A. Stach, Andrew D. Gamalski, Maarten Nachtegaal, Jingguang G. Chen, and Matthew Kottwitz
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X-ray absorption spectroscopy ,Materials science ,Diffuse reflectance infrared fourier transform ,Absorption spectroscopy ,02 engineering and technology ,General Chemistry ,Mesoporous silica ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Chemical reaction ,Catalysis ,0104 chemical sciences ,Chemical engineering ,Scanning transmission electron microscopy ,0210 nano-technology ,Bimetallic strip - Abstract
Alloy nanoparticle catalysts are known to afford unique activities that can differ markedly from their parent metals, but there remains a generally limited understanding of the nature of their atomic (and likely dynamic) structures as exist in heterogeneously supported forms under reaction conditions. Notably unclear is the nature of their active sites and the details of the varying oxidation states and atomic arrangements of the catalytic components during chemical reactions. In this work, we describe multimodal methods that provide a quantitative characterization of the complex heterogeneity present in the chemical and electronic speciations of Pt–Ni bimetallic catalysts supported on mesoporous silica during the reverse water gas shift reaction. The analytical protocols involved a correlated use of in situ X-ray Absorption Spectroscopy (XAS) and Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS), complimented by ex-situ aberration corrected Scanning Transmission Electron Microscopy (ST...
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- 2018
23. In situ surface stress measurement and computational analysis examining the oxygen reduction reaction on Pt and Pd
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Yair Cohen, Jeffrey Greeley, Thao T. H. Hoang, Ralph G. Nuzzo, Zhenhua Zeng, Yeyoung Ha, Andrew A. Gewirth, David J. Wetzel, and Justin Oberst
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Bulk modulus ,Materials science ,Bond strength ,General Chemical Engineering ,Surface stress ,Analytical chemistry ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrocatalyst ,01 natural sciences ,0104 chemical sciences ,Compressive strength ,Adsorption ,chemistry ,Ultimate tensile strength ,Electrochemistry ,0210 nano-technology ,Platinum - Abstract
Dynamic electrochemical surface stress response during the oxygen reduction reaction (ORR) on Pt and Pd cantilever electrodes in HClO 4 and KOH was examined to elucidate surface binding configurations during O 2 reduction electrocatalysis. Upon reduction of O 2 , the surface of Pt exhibits a compressive surface stress response, ΔStress, in both acid and base electrolytes due to adsorption of the ORR reactant and intermediates (O 2 , O, and OH). The magnitude of compressive ΔStress on Pt is greater in acid relative to base. On the other hand, the surface of Pd exhibits a negligible ΔStress in acid and a slight compressive ΔStress in base. Thus, magnitudes of the compressive ΔStress (surface expansion) during the ORR follow the order of Pt (acid) > Pt (base) > Pd (base) > Pd (acid) ∼ 0. Density functional theory (DFT) calculations of adsorbate-induced excess surface stress on Pt(111) and Pd(111) surfaces imply a greater compressive surface stress induced on Pt(111) for nearly all adsorbate geometries examined. This trend, which agrees with the experimental observations, can be correlated to a greater tensile intrinsic surface stress of Pt(111) relative to Pd(111) resulting from difference in bond strength and bulk modulus of two metals. On stepped Pt(221) and Pd(221) surfaces, both the intrinsic tensile stress of the clean surface and the adsorbate-induced excess compressive stress are significantly reduced due to the presence of less coordinated, flexible step sites. Moreover, this difference between surface stress at terrace and step sites is more pronounced on Pt, which exhibits a greater intrinsic surface stress.
- Published
- 2018
24. ZnAlxCo2–xO4 Spinels as Cathode Materials for Non-Aqueous Zn Batteries with an Open Circuit Voltage of ≤2 V
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Ralph G. Nuzzo, Andrew A. Gewirth, and Chengsi Pan
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Materials science ,Open-circuit voltage ,General Chemical Engineering ,Nanotechnology ,02 engineering and technology ,General Chemistry ,Electrolyte ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Environmentally friendly ,Energy storage ,Cathode ,0104 chemical sciences ,Anode ,law.invention ,law ,Materials Chemistry ,Forensic engineering ,0210 nano-technology ,Electrochemical potential ,Voltage - Abstract
Rechargeable Zn batteries are promising energy storage alternatives for Li-ion batteries in part because of the high specific and volumetric capacities of Zn anodes, as well as their low cost, improved prospects for safety, and the fact that they are environmentally friendly. Development efforts, however, have focused mostly on aqueous electrolyte systems, which are intrinsically limited by the narrow electrochemical potential window of water. As a consequence, the use of alternative non-aqueous electrolytes has attracted a growing level of interest with the hope that they may provide higher operational voltages, which potentially could provide viable pathways to high-energy and high-power density Zn batteries. With regard to the latter, the considerable progress made in developing useful non-aqueous electrolyte chemistries for Zn anodes has not been matched by correlated progress regarding the development of useful cathode materials. In this work, a new series of spinels, ZnAlxCo2–xO4, are reported and t...
- Published
- 2017
25. Refractive index sensing and surface-enhanced Raman spectroscopy using silver–gold layered bimetallic plasmonic crystals
- Author
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Tae-Woo Lee, An Phong Le, Somi Kang, Rohit Bhargava, Matthew V. Schulmerich, Stephen Gray, Sean E. Lehman, and Ralph G. Nuzzo
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finite-difference time-domain ,Materials science ,Fabrication ,General Physics and Astronomy ,Physics::Optics ,02 engineering and technology ,lcsh:Chemical technology ,lcsh:Technology ,01 natural sciences ,Full Research Paper ,plasmonics ,symbols.namesake ,nanoimprint soft lithography ,0103 physical sciences ,Nanotechnology ,lcsh:TP1-1185 ,General Materials Science ,Electrical and Electronic Engineering ,Surface plasmon resonance ,lcsh:Science ,010306 general physics ,Bimetallic strip ,Nanoscopic scale ,Plasmon ,lcsh:T ,business.industry ,Surface-enhanced Raman spectroscopy ,021001 nanoscience & nanotechnology ,lcsh:QC1-999 ,Nanoscience ,symbols ,Optoelectronics ,lcsh:Q ,0210 nano-technology ,business ,Raman spectroscopy ,Refractive index ,lcsh:Physics ,surface plasmon resonance - Abstract
Herein we describe the fabrication and characterization of Ag and Au bimetallic plasmonic crystals as a system that exhibits improved capabilities for quantitative, bulk refractive index (RI) sensing and surface-enhanced Raman spectroscopy (SERS) as compared to monometallic plasmonic crystals of similar form. The sensing optics, which are bimetallic plasmonic crystals consisting of sequential nanoscale layers of Ag coated by Au, are chemically stable and useful for quantitative, multispectral, refractive index and spectroscopic chemical sensing. Compared to previously reported homometallic devices, the results presented herein illustrate improvements in performance that stem from the distinctive plasmonic features and strong localized electric fields produced by the Ag and Au layers, which are optimized in terms of metal thickness and geometric features. Finite-difference time-domain (FDTD) simulations theoretically verify the nature of the multimode plasmonic resonances generated by the devices and allow for a better understanding of the enhancements in multispectral refractive index and SERS-based sensing. Taken together, these results demonstrate a robust and potentially useful new platform for chemical/spectroscopic sensing.
- Published
- 2017
26. 3D Printing High‐Resolution Conductive Elastomeric Structures with a Solid Particle‐Free Emulsion Ink
- Author
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Ralph G. Nuzzo, Chen Wang, Gaurav Chaudhary, and Randy H. Ewoldt
- Subjects
Materials science ,Solid particle ,Inkwell ,business.industry ,Emulsion ,3D printing ,High resolution ,General Materials Science ,Composite material ,Condensed Matter Physics ,business ,Elastomer ,Electrical conductor - Published
- 2021
27. Multimodal Study of the Speciations and Activities of Supported Pd Catalysts During the Hydrogenation of Ethylene
- Author
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Yuanyuan Li, Jing Liu, Alexander Orlov, Eric A. Stach, Andrew A. Gewirth, Shen Zhao, Anatoly I. Frenkel, Qiyuan Wu, Ralph G. Nuzzo, Deyu Liu, Dmitri N. Zakharov, and Yao Min Liu
- Subjects
Ethylene ,Hydride ,Inorganic chemistry ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,X-ray absorption fine structure ,Carbide ,Catalysis ,Chemical state ,chemistry.chemical_compound ,General Energy ,chemistry ,Physical and Theoretical Chemistry ,Microreactor ,0210 nano-technology ,Palladium - Abstract
In this work we describe a multimodal exploration of the atomic structure and chemical state of silica-supported palladium nanocluster catalysts during the hydrogenation of ethylene in operando conditions that variously transform the metallic phases between hydride and carbide speciations. The work exploits a microreactor that allows combined multiprobe investigations by high-resolution transmission electron microscopy (HR-TEM), X-ray absorption fine structure (XAFS), and microbeam IR (μ-IR) analyses on the catalyst under operando conditions. The work specifically explores the reaction processes that mediate the interconversion of hydride and carbide phases of the Pd clusters in consequence to changes made in the composition of the gas-phase reactant feeds, their stability against coarsening, the reversibility of structural/compositional transformations, and the role that oligomeric/waxy byproducts (here forming under hydrogen-limited reactant compositions) might play in modifying activity. The results pr...
- Published
- 2017
28. Evolution at the Solid Electrolyte/Gold Electrode Interface during Lithium Deposition and Stripping
- Author
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Lingzi Sang, Andrew A. Gewirth, Ralph G. Nuzzo, and Richard T. Haasch
- Subjects
Stripping (chemistry) ,Scanning electron microscope ,General Chemical Engineering ,Inorganic chemistry ,Analytical chemistry ,Ionic bonding ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,Electrolyte ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,X-ray photoelectron spectroscopy ,chemistry ,Materials Chemistry ,Fast ion conductor ,Deposition (phase transition) ,Lithium ,0210 nano-technology - Abstract
Quasi-binary thiophosphate-based solid electrolytes (SEs) are attracting substantial interest for lithium batteries due to their outstanding room temperature ionic conductivities. This work describes reactions occurring at the solid electrolyte (SE)/Au interface during Li deposition and stripping for two exemplary SE materials: β-Li3PS4 (β-LPS) and Li10GeP2S12 (LGPS). We used in situ Raman spectroscopy, along with X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) to evaluate potential-dependent changes in the chemistry of these materials at active electrode interfaces. For β-LPS, a partially reversible conversion of PS43– to P2S64– was found along with the formation of Li2S during Li deposition and stripping. In contrast, LGPS exhibited only irreversible changes at potentials below 0.7 V vs Li+/Li. The different behaviors likely relate to differences in the structures of the two SE materials and the availability of easily bridged anion components in close proximity. The work sh...
- Published
- 2017
29. Quantitative Reflection Imaging for the Morphology and Dynamics of Live Aplysia californica Pedal Ganglion Neurons Cultured on Nanostructured Plasmonic Crystals
- Author
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Jonathan V. Sweedler, John A. Rogers, Somi Kang, Stanislav S. Rubakhin, Adina Badea, and Ralph G. Nuzzo
- Subjects
0301 basic medicine ,Nanostructure ,Materials science ,Nanotechnology ,02 engineering and technology ,Article ,Crystal ,03 medical and health sciences ,Aplysia ,Electrochemistry ,Animals ,General Materials Science ,Surface plasmon resonance ,Thin film ,Spectroscopy ,Plasmon ,Neurons ,Finite-difference time-domain method ,Optical Devices ,Surfaces and Interfaces ,Surface Plasmon Resonance ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Polyelectrolyte ,Nanostructures ,030104 developmental biology ,Reflection (physics) ,sense organs ,0210 nano-technology - Abstract
We describe a reflection imaging system that consists of a plasmonic crystal, a common laboratory microscope, and band-pass filters for use in the quantitative imaging and in situ monitoring of live cells and their substrate interactions. Surface plasmon resonance (SPR) provides a highly sensitive method to monitor changes in physicochemical properties occurring at metal-dielectric interfaces. Polyelectrolyte thin films deposited using the layer-by-layer (LBL) self-assembly method provide a reference system for calibrating the reflection contrast changes that occur when the polyelectrolyte film thickness changes and provide insight into the optical responses that originate from the multiple plasmonic features supported by this imaging system. Finite-difference time-domain (FDTD) simulations of the optical responses measured experimentally from the polyelectrolyte reference system are used to provide a calibration of the optical system for subsequent use in quantitative studies investigating live cell dynamics in cultures supported on a plasmonic crystal substrate. Live Aplysia californica pedal ganglion neurons cultured in artificial seawater were used as a model system through which to explore the utility of this plasmonic imaging technique. Here, the morphology of cellular peripheral structures ≲80 nm in thickness were quantitatively analyzed, and the dynamics of their trypsin-induced surface detachment were visualized. These results illustrate the capacities of this system for use in investigations of the dynamics of ultrathin cellular structures within complex bioanalytical environments.
- Published
- 2017
30. Luminescent Solar Concentrator Tandem-on-Silicon with above 700mV Passivated Contact Silicon Bottom Cell
- Author
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Ralph G. Nuzzo, San Theingi, Zach Nett, Brent A. Koscher, Dawn Findley, John F. Geisz, Harry A. Atwater, A. Paul Alivisatos, Colton R. Bukowsky, Megan Phelan, Ognjen Ilic, David R. Needell, Hanxiao Su, Paul Stradins, Haley Bauser, and William Nemeth
- Subjects
Materials science ,Silicon ,Tandem ,business.industry ,Luminescent solar concentrator ,chemistry.chemical_element ,Waveguide (optics) ,Optical coupling ,chemistry ,Area coverage ,Optoelectronics ,sense organs ,business ,Lauryl methacrylate ,Overall efficiency - Abstract
Luminescent solar concentrator (LSC) tandem-on-silicon (Si) provides a route towards achieving higher than 30% overall efficiency which can overcome the theoretical efficiency limit of a single junction Si cell. Here, we present optical coupling and performance of high V oc passivated contact Si bottom cell for LSC tandem-on-Si where the top module consists of highly efficient luminophores and an array of micro InGaP cells embedded in a poly (lauryl methacrylate) waveguide. In this device configuration, InGaP cell area coverage is only ~0.5% of the total LSC area which significantly reduces the high cost III-V material usage. The performance of Si sub-cell is investigated under LSC spectrum and is compared against the measurement done under 1 μm thick InGaP filter which mimics the spectrum seen by Si bottom cell in a conventional III-V/Si tandem. V oc of greater than 700 mV has been observed for the passivated contact Si bottom cell in these tandem applications.
- Published
- 2019
31. Light Material Interactions in Energy Conversion (Final Report)
- Author
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Xiang Zhang, Eli Yablonovitch, Shanhui Fan, John A. Rogers, Nathan S. Lewis, Paul V. Braun, Andrei Faraon, Ralph G. Nuzzo, Austin J. Minnich, Harry A. Atwater, Jennifer A. Dionne, Jennifer A. Lewis, A. Paul Alivisatos, and Mark L. Brongersma
- Subjects
Materials science ,business.industry ,Optoelectronics ,Energy transformation ,business - Published
- 2019
32. Design Criteria for Micro-Optical Tandem Luminescent Solar Concentrators
- Author
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John F. Geisz, Harry A. Atwater, Colton R. Bukowsky, Zach Nett, Junwen He, Ralph G. Nuzzo, Lu Xu, A. Paul Alivisatos, Benjamin G. Lee, Ognjen Ilic, Haley Bauser, and David R. Needell
- Subjects
Materials science ,luminescent devices ,quantum dots ,tandem PV ,02 engineering and technology ,III-V concentrator photovoltaics ,01 natural sciences ,Waveguide (optics) ,010309 optics ,chemistry.chemical_compound ,0103 physical sciences ,Electrical and Electronic Engineering ,Quantum Physics ,Tandem ,Cadmium selenide ,business.industry ,Photovoltaic system ,Energy conversion efficiency ,Monte Carlo methods ,Materials Engineering ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,chemistry ,Quantum dot ,Luminophore ,Optoelectronics ,Photonics ,0210 nano-technology ,business - Abstract
© 2018 IEEE. Luminescent solar concentrators (LSCs) harness light generated by luminophores embedded in a light-trapping waveguide to concentrate onto smaller cells. LSCs can absorb both direct and diffuse sunlight, and thus can operate as flat plate receivers at a fixed tilt and with a conventional module form factor. However, current LSCs experience significant power loss through parasitic luminophore absorption and incomplete light trapping by the optical waveguide. Here, we introduce a tandem LSC device architecture that overcomes both of these limitations, consisting of a poly(lauryl methacrylate) polymer layer with embedded cadmium selenide core, cadmium sulfide shell (CdSe/CdS) quantum dot (QD) luminophores and an InGaP microcell array, which serves as high bandgap absorbers on the top of a conventional Si photovoltaic. We investigate the design space for a tandem LSC, using experimentally measured performance parameters for key components, including the InGaP microcell array, CdSe/CdS QDs, and spectrally selective waveguide filters. Using a Monte Carlo ray-tracing model, we compute the power conversion efficiency for a tandem LSC module with these components to be 29.4% under partially diffuse illumination conditions. These results indicate that a tandem LSC-on-Si architecture could significantly improve upon the efficiency of a conventional Si photovoltaic cell.
- Published
- 2018
33. High Energy Density and Stable Three‐Dimensionally Structured Se‐Loaded Bicontinuous Porous Carbon Battery Electrodes
- Author
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Ke Yang, Paul V. Braun, Shiyan Zhang, Subing Qu, Runyu Zhang, Jagjit Nanda, Ralph G. Nuzzo, and Junjie Wang
- Subjects
Battery (electricity) ,General Energy ,Porous carbon ,Materials science ,chemistry ,Vinylene carbonate ,Chemical engineering ,Electrode ,Energy density ,chemistry.chemical_element ,Selenium - Published
- 2021
34. Bio‐Compliant Composites: Biocompliant Composite Au/pHEMA Plasmonic Scaffolds for 3D Cell Culture and Noninvasive Sensing of Cellular Metabolites (Adv. Healthcare Mater. 4/2021)
- Author
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Lou Ann Miller, Sanjaya Jayalath, Ralph G. Nuzzo, Sean E. Lehman, and Joselle M. McCracken
- Subjects
Biomaterials ,3D cell culture ,Materials science ,Composite number ,Biomedical Engineering ,Pharmaceutical Science ,Nanotechnology ,Plasmon - Published
- 2021
35. 3D Particle‐Free Printing of Biocompatible Conductive Hydrogel Platforms for Neuron Growth and Electrophysiological Recording
- Author
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Jonathan V. Sweedler, Michael J. Enright, Ralph G. Nuzzo, Stanislav S. Rubakhin, and Chen Wang
- Subjects
Materials science ,Neurite ,biology ,Biocompatibility ,technology, industry, and agriculture ,Condensed Matter Physics ,Methacrylate ,biology.organism_classification ,Article ,Electronic, Optical and Magnetic Materials ,Biomaterials ,Electrophysiology ,Aplysia ,Self-healing hydrogels ,Conductive ink ,Electrochemistry ,In situ polymerization ,Biomedical engineering - Abstract
Electrically conductive 3D periodic microscaffolds are fabricated using a particle-free direct ink writing approach for use as neuronal growth and electrophysiological recording platforms. A poly (2-hydroxyethyl methacrylate) (pHEMA)/pyrrole ink, followed by chemical in situ polymerization of pyrrole, enables hydrogel printing through nozzles as small as 1 μm. These conductive hydrogels can pattern complex 2D and 3D structures and have good biocompatibility with test cell cultures (~94.5% viability after 7 days). Hydrogel arrays promote extensive neurite outgrowth of cultured Aplysia californica pedal ganglion neurons. This platform allows extracellular electrophysiological recording of steady-state and stimulated electrical neuronal activities. In summation, this 3D conductive ink printing process enables preparation of biocompatible and micron-sized structures to create customized in vitro electrophysiological recording platforms.
- Published
- 2021
36. Design, fabrication, and characterization of a proposed microchannel water electrolyzer
- Author
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Ralph G. Nuzzo, Amit V. Desai, Muhammed Enes Oruc, and Paul J. A. Kenis
- Subjects
Engineering ,Hydrogen ,High-pressure electrolysis ,Mechanical engineering ,chemistry.chemical_element ,Energy Engineering and Power Technology ,02 engineering and technology ,law.invention ,law ,Waste heat ,0502 economics and business ,050207 economics ,Physical and Theoretical Chemistry ,Electrical and Electronic Engineering ,Electrolysis ,Microchannel ,Electrolysis of water ,business.industry ,Renewable Energy, Sustainability and the Environment ,05 social sciences ,Photovoltaic system ,021001 nanoscience & nanotechnology ,Electrochemical energy conversion ,chemistry ,Optoelectronics ,0210 nano-technology ,business - Abstract
Solar energy-powered water electrolysis is a cost-effective and scalable method to produce hydrogen, an environment-friendly and potentially sustainable energy carrier. To this end, we report a microchannel water electrolyzer with a planar design that can be integrated with a photovoltaic cell, where the electrolyzer utilizes the waste heat generated during the photoelectric process to enhance the production of hydrogen (and oxygen) via the electrochemical splitting of water. We performed a systematic parametric investigation to study the effect of the channel dimensions, electrolyte temperature and flow rate, and the mode of operation (pulsed vs. continuous) on the electrolyzer's performance. The balance between mass, heat and ion/charge transport limitations acts to determine an optimal geometry and specific operating conditions for the device. The highest hydrogen production rate was observed for pulsed operation (15 s pulses) at a temperature of 60 °C, and a potential of 2.0 V, for a 400-μm tall electrolyzer chamber. We also show that tuning of the geometry and operating conditions can yield an almost 7-fold increase in the hydrogen production rate. This study not only reports a new and improved approach over existing photovoltaic thermal systems but also presents design and operational considerations for microfluidic-based electrochemical energy devices.
- Published
- 2016
- Full Text
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37. Programming Mechanical and Physicochemical Properties of 3D Hydrogel Cellular Microcultures via Direct Ink Writing
- Author
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Adina Badea, Joselle M. McCracken, Ralph G. Nuzzo, A. Sydney Gladman, Gabriel Popescu, David J. Wetzel, Mikhail E. Kandel, and Jennifer A. Lewis
- Subjects
Materials science ,Biocompatibility ,Confocal ,Biomedical Engineering ,Pharmaceutical Science ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Biomaterials ,Mice ,Tissue engineering ,Live cell imaging ,Microscopy ,Fluorescence microscope ,Animals ,Polylysine ,Polyhydroxyethyl Methacrylate ,Tissue Scaffolds ,Substrate (chemistry) ,Hydrogels ,Fibroblasts ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Self-healing hydrogels ,NIH 3T3 Cells ,0210 nano-technology ,Biomedical engineering - Abstract
3D hydrogel scaffolds are widely used in cellular microcultures and tissue engineering. Using direct ink writing, microperiodic poly(2-hydroxyethyl-methacrylate) (pHEMA) scaffolds are created that are then printed, cured, and modified by absorbing 30 kDa protein poly-l-lysine (PLL) to render them biocompliant in model NIH/3T3 fibroblast and MC3T3-E1 preosteoblast cell cultures. Spatial light interference microscopy (SLIM) live cell imaging studies are carried out to quantify cellular motilities for each cell type, substrate, and surface treatment of interest. 3D scaffold mechanics is investigated using atomic force microscopy (AFM), while their absorption kinetics are determined by confocal fluorescence microscopy (CFM) for a series of hydrated hydrogel films prepared from prepolymers with different homopolymer-to-monomer (Mr ) ratios. The observations reveal that the inks with higher Mr values yield relatively more open-mesh gels due to a lower degree of entanglement. The biocompatibility of printed hydrogel scaffolds can be controlled by both PLL content and hydrogel mesh properties.
- Published
- 2016
38. Comprehensive energy analysis of a photovoltaic thermal water electrolyzer
- Author
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Amit V. Desai, Ralph G. Nuzzo, Paul J. A. Kenis, and Muhammed Enes Oruc
- Subjects
Engineering ,Waste management ,business.industry ,020209 energy ,Mechanical Engineering ,Photovoltaic system ,02 engineering and technology ,Building and Construction ,Management, Monitoring, Policy and Law ,021001 nanoscience & nanotechnology ,Renewable energy ,Photovoltaic thermal hybrid solar collector ,General Energy ,High-temperature electrolysis ,Waste heat ,Active cooling ,0202 electrical engineering, electronic engineering, information engineering ,0210 nano-technology ,Process engineering ,business ,Electrical efficiency ,Hydrogen production - Abstract
The use of photovoltaic thermal (PVT) technologies enables improvement in the electrical efficiency of a photovoltaic (PV) module by reducing the temperature of the PV module via active waste heat removal. In current PVT systems, the removed heat is mainly used for specific applications, such as water and/or room heating, but their need is intermittent and seasonal. For a more efficient and versatile use of the removed waste heat, we propose a new architecture where the PV module is integrated with a dual-functional electrolyzer that removes the waste heat by active cooling and produces hydrogen via electrolysis. The excess heat from the PV cell is utilized to enhance the reaction kinetics of the electrolysis process (due to an increase in temperature) inside an electrolyzer, which is located below the PV module. In this paper, we used finite-element analysis (FEA) simulations to optimize the geometry and operating conditions of an electrolyzer to maximize overall energetic efficiency and hydrogen production. To evaluate the practical feasibility of the approach, we performed a comprehensive energy analysis of the PVTE system using data from Phoenix, AZ. The energetic efficiency of the proposed PVTE system was calculated to be 56–59%, which is comparable to those of current PVT systems. Additionally, the integration of the electrolyzer with the PV module led to an almost 2.5-fold increase in hydrogen production compared to a stand-alone electrolyzer operated at ambient temperature. The analyzed hybrid approach potentially represents a viable and useful alternative for utilization of waste heat energy from PV cells. This approach may further increase the use of photovoltaic technologies as a renewable energy source.
- Published
- 2016
39. Enhanced Photon Collection in Luminescent Solar Concentrators with Distributed Bragg Reflectors
- Author
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Noah D. Bronstein, A. Paul Alivisatos, Yuan Yao, Lu Xu, Ralph G. Nuzzo, and Lanfang Li
- Subjects
Materials science ,Luminescent solar concentrator ,Physics::Optics ,02 engineering and technology ,Stopband ,010402 general chemistry ,01 natural sciences ,symbols.namesake ,chemistry.chemical_compound ,Optics ,Stokes shift ,Refractive index contrast ,Electrical and Electronic Engineering ,Absorption (electromagnetic radiation) ,business.industry ,021001 nanoscience & nanotechnology ,Distributed Bragg reflector ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,chemistry ,symbols ,Luminophore ,Optoelectronics ,Photonics ,0210 nano-technology ,business ,Biotechnology - Abstract
Escape cone loss is one of the primary limiting factors for efficient photon collection in large-area luminescent solar concentrators (LSCs). The Stokes shift of the luminophore, however, opens up an opportunity to recycle the escaped luminescence at the LSC front surface by utilizing a photonic band-stop filter that reflects photons in the luminophore’s emission range while transmitting those in its absorption range. In this study, we examine the functional attributes of such photonic filter designs, ones realized here in the form of a distributed Bragg reflector (DBR) fabricated by spin-coating alternating layers of SiO2 and SnO2 nanoparticle suspensions onto a supportive glass substrate. The central wavelength and the width of the photonic stopband were programmatically tuned by changing the layer thickness and the refractive index contrast between the two dielectric materials. We explore the design sensitivities for a DBR with an optimized stopband frequency that can effectively act as a top angle-res...
- Published
- 2016
40. Dynamic Surface Stress Response during Reversible Mg Electrodeposition and Stripping
- Author
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Christopher J. Barile, Jinho Chang, Andrew A. Gewirth, Ralph G. Nuzzo, Jeffrey Greeley, Zhenhua Zeng, and Yeyoung Ha
- Subjects
Materials science ,Renewable Energy, Sustainability and the Environment ,Surface stress ,Inorganic chemistry ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Stripping (fiber) ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Materials Chemistry ,Electrochemistry ,0210 nano-technology - Published
- 2016
41. Solution processes for ultrabroadband and omnidirectional graded-index glass lenses with near-zero reflectivity in high concentration photovoltaics
- Author
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Jeonghyun Kim, Junwen He, Ralph G. Nuzzo, Rabab R. Bahabry, Seungyong Han, Hongwoo Jang, Brent Fisher, John A. Rogers, Jae Hwan Kim, Myeong Namkoong, Jaewon Choi, Nina Hong, Muhammad Mustafa Hussain, Sung Bong Kim, Jung Woo Lee, Scott Burroughs, Kyu-Tae Lee, Sanjay V. Kalidindi, and Yuan Yao
- Subjects
Photocurrent ,Microlens ,Multidisciplinary ,Materials science ,business.industry ,lcsh:R ,lcsh:Medicine ,02 engineering and technology ,Fresnel equations ,021001 nanoscience & nanotechnology ,01 natural sciences ,Article ,010309 optics ,Photovoltaics ,0103 physical sciences ,Optoelectronics ,Energy transformation ,lcsh:Q ,Image sensor ,lcsh:Science ,0210 nano-technology ,Omnidirectional antenna ,business ,Microscale chemistry - Abstract
Concentrator photovoltaic (CPV) systems, where incident direct solar radiation is tightly concentrated onto high-efficiency multi-junction solar cells by geometric optical elements, exhibit the highest efficiencies in converting the sun’s energy into electric power. Their energy conversion efficiencies are greatly limited, however, due to Fresnel reflection losses occurring at three air/optics interfaces in the most sophisticated dual-stage CPV platforms. This paper describes a facile one-step wet-etching process to create a nanoporous surface with a graded-index profile on both flat and curved glasses, with capabilities of achieving ~99% average transmission efficiency in a wide wavelength range from 380 nm to 1.3 µm and for a wide range of incident angles up to ±40° regardless of the polarization state of incident sunlight. The simplicity of the etching process remarkably increases their versatility in various optical elements that require unconventional form factors such as Fresnel lenses and microlens arrays, and/or demanding curvatures along with much reduced dimensions such as ball lenses. Etched glass surfaces on two-stage optical concentrating systems yield enhancements in total optical transmission efficiencies by 13.8% and in the photocurrent by 14.3%, as experimentally determined by measurements on microscale triple-junction solar cells. The presented strategy can be widely adapted in a variety of applications such as image sensors, display systems, and other optoelectronic devices.
- Published
- 2018
42. In Situ Strain Measurement in Solid-State Li-Ion Batteries
- Author
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Lingzi Sang, Behrad Koohbor, Andrew A. Gewirth, Scott R. White, Ralph G. Nuzzo, Ömer Özgür Çapraz, and Nancy R. Sottos
- Subjects
Battery (electricity) ,Digital image correlation ,Materials science ,Electrode ,Fast ion conductor ,Solid-state battery ,Electrolyte ,Fade ,Composite material ,Ion - Abstract
Volumetric changes due to repeated lithiation and delithiation are a significant source of electrode degradation and capacity fade in rechargeable batteries. Measurement of such volumetric changes and their resultant electro-chemo-mechanical strains and stresses have previously been investigated in conventional liquid-electrolyte Li-ion batteries. In the present study, we propose to extend the current knowledge and measurement techniques into the area of all-solid-state Li-ion batteries. Due to the presence of inherent property mismatch as well as confinements imposed at the interfaces between the electrodes and solid electrolyte, solid-state battery components are more prone to interfacial damage and. In this work, novel experimental approaches are designed to facilitate in-situ strain measurements on solid electrolytes (SE), electrodes and SE/electrode interface. Digital image correlation (DIC) is utilized to enable full-field strain measurements.
- Published
- 2018
43. Deterministic Integration of Biological and Soft Materials onto 3D Microscale Cellular Frameworks
- Author
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Zijun Wei, Zheng Yan, Joselle M. McCracken, Stanislav S. Rubakhin, Qing Lin, Jung Woo Lee, Matt Pharr, Ralph G. Nuzzo, Kyung In Jang, Sheng Xu, Jonathan V. Sweedler, David J. Wetzel, Jessica Su, Kewang Nan, John A. Rogers, Mikayla A. Anderson, Adina Badea, Mengdi Han, and Renhan Wang
- Subjects
Materials science ,3D scaffolds ,Biomedical Engineering ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,General Biochemistry, Genetics and Molecular Biology ,Contact guidance ,Article ,Biomaterials ,Leverage (statistics) ,Functional integration ,direct ink writing ,Microscale chemistry ,hydrogels ,Living matter ,Class (computer programming) ,021001 nanoscience & nanotechnology ,compressive-assembly ,Soft materials ,Biological materials ,0104 chemical sciences ,cellular contact guidance ,Generic health relevance ,0210 nano-technology - Abstract
Complex 3D organizations of materials represent ubiquitous structural motifs found in the most sophisticated forms of matter, the most notable of which are in life-sustaining hierarchical structures found in biology, but where simpler examples also exist as dense multilayered constructs in high-performance electronics. Each class of system evinces specific enabling forms of assembly to establish their functional organization at length scales not dissimilar to tissue-level constructs. This study describes materials and means of assembly that extend and join these disparate systems—schemes for the functional integration of soft and biological materials with synthetic 3D microscale, open frameworks that can leverage the most advanced forms of multilayer electronic technologies, including device-grade semiconductors such as monocrystalline silicon. Cellular migration behaviors, temporal dependencies of their growth, and contact guidance cues provided by the nonplanarity of these frameworks illustrate design criteria useful for their functional integration with living matter (e.g., NIH 3T3 fibroblast and primary rat dorsal root ganglion cell cultures).
- Published
- 2018
44. Operando Characterization of Catalysts through use of a Portable Microreactor
- Author
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Yuanyuan Li, Ralph G. Nuzzo, Stephen Crowley, Eli Stavitski, Shen Zhao, Dmitri N. Zakharov, Ryan Tappero, Eric A. Stach, Marco J. Castaldi, and Anatoly I. Frenkel
- Subjects
Inorganic Chemistry ,Elemental composition ,Chemistry ,Organic Chemistry ,Nanotechnology ,Physical and Theoretical Chemistry ,Microreactor ,Heterogeneous catalysis ,Catalysis ,Nanomaterial-based catalyst ,Characterization (materials science) - Abstract
In order to more deeply understand the mechanisms of catalytic reactions, improved methods are needed to monitor changes that occur in the electronic, structural, and chemical properties of catalytic systems under the conditions in which they work. We describe here a microreactor-based approach that integrates the capabilities of advanced X-ray, electron, optical, and gas-phase compositional analysis techniques under operando conditions. For several exemplary catalytic systems, we demonstrate how this approach enables the characterization of three of the major factors that contribute to structure–property correlations in heterogeneous catalysis. Specifically, we describe how this approach can be used to better understand the atomic structure and elemental composition of nanocatalysts, the physiochemical properties of the support and catalyst/support interfaces, and the gas- and surface-phase chemistry that occurs under operando conditions. We highlight the generality of the approach, as well as opportunities for future developments.
- Published
- 2015
45. Improving Electrodeposition of Mg through an Open Circuit Potential Hold
- Author
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Jennifer Esbenshade, Andrew A. Gewirth, Christopher J. Barile, Timothy T. Fister, Paul Fenter, Ralph G. Nuzzo, and Kimberly L. Bassett
- Subjects
Materials science ,Open-circuit voltage ,Analytical chemistry ,Electrolyte ,Electrochemistry ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,General Energy ,X-ray photoelectron spectroscopy ,Chemical engineering ,Electrode ,Crystallite ,Physical and Theoretical Chemistry ,Layer (electronics) ,Deposition (law) - Abstract
We used in situ X-ray diffraction, XPS, SEM, and electrochemical methods to interrogate the mechanism of Mg electrodeposition from PhMgCl/AlCl3 (APC) and EtMgCl electrolytes. An open circuit potential (OCP) pause following Mg deposition led to retained enhancement of Mg deposition and stripping kinetics along with lowered overpotentials for both. In situ X-ray diffraction demonstrated that the OCP pause led to a more polycrystalline deposit relative to that without the pause, while SEM presented micrographs that showed smaller deposits with an OCP hold. The improvement is attributed to an “enhancement layer” that formed on the electrode during the OCP hold. Analysis of XPS data suggests that the “enhancement layer” consists of Mg and Cl retained on the electrode surface, possibly following electrode depassivation.
- Published
- 2015
46. Exploring Salt and Solvent Effects in Chloride-Based Electrolytes for Magnesium Electrodeposition and Dissolution
- Author
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Christopher J. Barile, Andrew A. Gewirth, and Ralph G. Nuzzo
- Subjects
chemistry.chemical_classification ,Magnesium ,Inorganic chemistry ,chemistry.chemical_element ,Salt (chemistry) ,Electrolyte ,Electrochemistry ,Chloride ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Solvent ,General Energy ,chemistry ,medicine ,Physical and Theoretical Chemistry ,Solvent effects ,Dissolution ,medicine.drug - Abstract
We describe in this work Mg electrodeposition and dissolution from a wide range of inorganic ethereal electrolytes consisting of MgCl2 and a second chloride salt. Systematic variations of the cosalt reveal two broad classes of electrolytes, namely, the group 13 electrolytes, which require electrolytic cycling to improve their performance, and electrolytes based on heavy p-block chlorides, which exhibit Mg intermetallic formation. Results from electrospray ionization mass spectrometry demonstrate that Mg deposition and stripping only occur in electrolytes containing Mg multimers. We also explore the role of solvent in determining the electrochemical performance of chloride-based electrolytes. Our analysis establishes thermodynamic parameters that dictate the ability of a solvent to support Mg electrochemistry in the MgCl2–AlCl3 system. In their totality, these results illustrate important electrolyte design guidelines for future Mg-ion batteries.
- Published
- 2015
47. Programming matter through strain
- Author
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Michael J. Motala, Peixi Yuan, Ralph G. Nuzzo, K. Jimmy Hsia, Daniel Perlitz, and Christopher M. Daly
- Subjects
Fabrication ,Materials science ,Polydimethylsiloxane ,business.industry ,Mechanical Engineering ,Bioengineering ,Photoresist ,Light scattering ,Programmable matter ,chemistry.chemical_compound ,Optics ,chemistry ,Mechanics of Materials ,Chemical physics ,Metastability ,Ultraviolet light ,Chemical Engineering (miscellaneous) ,Photomask ,business ,Engineering (miscellaneous) - Abstract
We describe the use of light in a lithographic form of grayscale patterning as a means to program the properties and folding mechanics of flat, thin-film-polymeric materials. In this process, a finely dispersed (phase-separated) mixture of photoresist (SU-8 50) in polydimethylsiloxane (PDMS) is irradiated with ultraviolet light through a photomask. The subsequent photoresist cross-linking in the exposed regions causes changes in the material’s chemo-mechanical properties (notably making it stiffer and more resistant to solvent-induced swelling in the area of exposure). Light scattering due to the dispersed, non-index-matched photoresist domains leads to an intrinsic grayscale profile of the pattern width through the depth of the exposure field, a feature bringing significant and previously unexplored consequences for strain-induced folding dynamics. Solvent induced swelling, where PDMS absorbs a nonpolar solvent, is used to actuate folding mechanics with complex temporal and spatial profiles that explicitly follow the design rules established by the gradient cross-link density, features that elicit a programmable swelling (and therefore, folding) of the two-dimensional sheets. During investigation and optimization of the system, we observed an interesting temporal and biomimetic folding phenomenon that distinguishes the current results from other forms of strain induced folding reported in the literature. Under specific fabrication parameters, an evolution through an intermediate metastable state is observed, one in which the material will fold in one direction, then flatten and fold in the opposite direction. Mechanics modeling and finite element simulations have led to a detailed understanding of the system and the dynamics that allow a temporal evolution of 3-D structure through a double mode of folding. Insights into these mechanisms provide an advanced understanding of strain-induced folding in the field of soft materials.
- Published
- 2015
48. Comparative in Operando Studies in Heterogeneous Catalysis: Atomic and Electronic Structural Features in the Hydrogenation of Ethylene over Supported Pd and Pt Catalysts
- Author
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Matthew W. Small, Annika Elsen, Anatoly I. Frenkel, Ralph G. Nuzzo, Jeremy G. Smith, Yuanyuan Li, Ulrich Jung, and Eric A. Stach
- Subjects
chemistry.chemical_compound ,Olefin fiber ,Ethylene ,Chemistry ,Design elements and principles ,Nanotechnology ,General Chemistry ,Electronic structure ,Experimental methods ,Heterogeneous catalysis ,Catalysis ,Characterization (materials science) - Abstract
There exists an emerging opportunity, engendered by advances made in experimental methods of research, to address long-standing questions about the nature of the molecular mechanisms that are operative in important heterogeneous catalytic processes, as well as the nature of the complex atomic and electronic structural features that mediate them. Of particular interest in this regard is the understanding of the dynamical attributes of catalytic processes—an understanding that might allow design principles to be applied to optimize the atomic and electronic structure of heterogeneous catalysts to sustain their performance in essentially any operating process condition. The current work explores these ideas—highlighting capabilities of in operando methods of spectroscopic characterization as applied to an exemplary heterogeneous catalytic process, olefin hydrogenation. No heterogeneous catalytic process has been studied more intensively than olefin hydrogenation. The extensive literature available establishe...
- Published
- 2015
49. Synergetic Role of Li+ during Mg Electrodeposition/Dissolution in Borohydride Diglyme Electrolyte Solution: Voltammetric Stripping Behaviors on a Pt Microelectrode Indicative of Mg–Li Alloying and Facilitated Dissolution
- Author
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Paul V. Braun, Andrew A. Gewirth, Jinwoo Kim, Jinho Chang, T. Spila, Ralph G. Nuzzo, and Richard T. Haasch
- Subjects
chemistry.chemical_compound ,Materials science ,chemistry ,Stripping (chemistry) ,Inorganic chemistry ,General Materials Science ,Diglyme ,Ultramicroelectrode ,Electrolyte ,Electrochemistry ,Borohydride ,Dissolution ,Redox - Abstract
We describe a voltammetric and spectroscopic study of Mg electrodeposition/dissolution (MgDep/Dis) in borohydride diglyme electrolyte solution containing Li(+) carried out on a Pt ultramicroelectrode (UME, r = 5 μm). The data reveal Li(+) cation facilitation that has not been previously recognized in studies made using macroelectrodes. While a single broad, asymmetric stripping peak is expected following MgDep on a Pt macroelectrode in 0.1 M Mg(BH4)2 + 1.5 M LiBH4 diglyme solution on a Pt UME, the stripping reveals three resolved oxidation peaks, suggesting that MgDep/Dis consists of not only a Mg/Mg(2+) redox reaction but also contributions from Mg-Li alloying/dissolution reaction processes. Detailed XPS, SIMS, ICP, and XRD studies were performed that confirm the importance of Mg-Li alloy formation processes, the nature of which is dependent on the reduction potential used during the MgDep step. Based on the electrochemical and surface analysis data, we propose an electrochemical mechanism for MgDep/Dis in a borohydride diglyme electrolyte solution that, in the presence of 1.5 M Li(+) ions, proceeds as follows: (1) Mg(2+) + 2e(-) ⇌ Mg; (2) (1 - x)Mg(2+) + xLi(+) + (2 - x)e(-) ⇌ Mg(1-x)Lix, 0x ≤ 0.02; and (3) (1 - y)Mg(2+) + yLi(+) + (2 - y)e(-) ⇌ Mg(1-y)Liy, 0.02y ≤ 0.09. Most significantly, we find that the potential-dependent MgDep/Dis kinetics are enhanced as the concentration of the LiBH4 in the diglyme electrolyte is increased, a result reflecting the facilitating influences of reduced uncompensated resistance and the enhanced electro-reduction kinetics of Mg(2+) due to Mg-Li alloy formation.
- Published
- 2015
50. Assembly of micro/nanomaterials into complex, three-dimensional architectures by compressive buckling
- Author
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Zheng Yan, Renhan Wang, Huanyu Cheng, Jeonghyun Kim, Yonggang Huang, Yihui Zhang, Adina Badea, Ungyu Paik, Fu Haoran, Wen Ren, Dongqing Xiao, Jung Woo Lee, Matthew T. Flavin, Ha Uk Chung, John A. Rogers, Sheng Xu, Yuhao Liu, Guoyan Zhou, Joselle M. McCracken, Zijun Wei, Wen Huang, Kyung In Jang, Ralph G. Nuzzo, Xiuling Li, and Anthony Banks
- Subjects
Multidisciplinary ,Cuboid ,Materials science ,Nanostructure ,Buckling ,Geometric transformation ,Nanotechnology ,Conical surface ,Advanced materials ,Nanomaterials - Abstract
Popping materials and devices from 2D into 3D Curved, thin, flexible complex three-dimensional (3D) structures can be very hard to manufacture at small length scales. Xu et al. develop an ingenious design strategy for the microfabrication of complex geometric 3D mesostructures that derive from the out-of-plane buckling of an originally planar structural layout (see the Perspective by Ye and Tsukruk). Finite element analysis of the mechanics makes it possible to design the two 2D patterns, which is then attached to a previously strained substrate at a number of points. Relaxing of the substrate causes the patterned material to bend and buckle, leading to its 3D shape. Science , this issue p. 154 ; see also p. 130
- Published
- 2015
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