Monica Jung de Andrade, The University of Texas at Dallas
Maria Perez Barthaburu, University de la Republica
Yin Ting Teng, Republic Polytechnic
Babak Anasori, Drexel University
Bio-Logic USA, LLC
Materials Today ǀ Elsevier
National Science Foundation
The University of Texas at Dallas, Alan G. MacDiarmid NanoTech Institute
The University of Texas at Dallas, School of Natural Sciences and Mathematics
NM04.01: Synthesis and Nanomanufacturing I
Monica Jung de Andrade
Maia Mombrú Frutos
Monday AM, November 26, 2018
Sheraton, 2nd Floor, Back Bay C
8:30 AM - NM04.01.01
Molten-Salt Synthesis of Iridium Oxide Nanorods for Oxygen and Hydrogen Evolution Reactions
Yuanbing Mao1,Jahangeer Ahmed1,Swati Mohan1
The University of Texas at Rio Grande Valley1Show Abstract
Electrocatalytic water splitting has been considered as a viable strategy to convert and store energy renewably, but has been hampered by the slow kinetics of the oxygen evolution reaction (OER). Hence there is an urgent need to improve the performance of currently used materials and/or develop new materials. Iridium oxide is an effective stable electrocatalyst with low over-potential and high current for efficient fuel generation technologies. To further improve its activity, we developed a facile one-step molten salt synthesis process to generate ultrafine iridium oxide nanorods (IrO2 NRs). The electrocatalytic performance of these IrO2 NCs for OER in acidic media was compared with that of commercial IrO2 nanoparticles (NPs) in terms of specific capacitance, total charge, most accessible charge, electrochemically active surface area, and roughness factor. Our IrO2 NRs demonstrated enhanced electrocatalytic OER activity in 0.5 M H2SO4 compared to the commercial IrO2 NPs. Moreover, compared to commercial IrO2 NPs and previous reports, our IrO2 NRs showed enhanced electrocatalytic activity for both OER and HER after passing either N2 or O2 gas in a 0.5 M KOH electrolyte, as confirmed by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. Our results are comparable with, and in most cases, higher than reported data in the literature. Therefore, the current study reported a type of highly electrocatalytic efficient IrO2 nanostructures, but also a simplistic, reliable and scalable synthetic process for them. It is expected that these IrO2 NRs can serve as a benchmark in the development of active OER and HER (photo)electrocatalysts for various applications in the near future.
8:45 AM -
9:15 AM - NM04.01.03
Gamma-Radiation-Induced Synthesis of Metal and Metal Oxide Nanoparticles
The Royal Institute of Technology1Show Abstract
Gamma-radiation-induced synthesis of metal and metal oxide nanoparticles involves reactions of dissolved precursor metal salts with products of water radiolysis. When exposed to ionizing radiation water decomposes to form chemically reactive radicals and molecular species. The products of water radiolysis range from highly oxidizing, e.g. hydroxyl radicals to highly reducing, e.g. hydrogen radicals and solvated electrons. The oxidants and reductants produced upon radiolysis react then with solutes and change their oxidation state. These chemical changes lead to the formation and subsequent precipitation of insoluble species, since the solubility and reactivity of metal ions depend on their oxidation states. Synthesis of nanomaterials can be done by using either reductive or oxidative routes. To reach the controlled redox conditions and avoid the unwanted reactions one can add other organic or inorganic compounds which act as scavengers of the radicals. The amount of material obtained by gamma- radiation-induced synthesis can be controlled by the yield of reductive/oxidative radiolysis products formed in solution. Radiation induced synthesis is a powerful tool to produce the materials of complex shape and compositions. It has the following advantages as compared to the other methods: The nanoparticles with very narrow size distribution and uniform shape can be synthesized; there are possibilities to synthesize the nanostructure in confined media, such as porous materials, nanotubes etc. The formation of radicals stops immediately when the solution is removed from the radioactive source. Therefore the amount of reacting radicals and thus the amount of obtained precipitate is controlled by the total radiation dose with a high accuracy. Moreover, the radiation induced method is cost-effective processing, since it implies direct energy transfer without intervening media. It has low energy consumptions, since the radiation source does not require external energy supply. It requires minimal use of potentially harmful chemicals (initiators, crosslinking agents, acids etc.). Thus, radiation-induced synthesis can be considered as a green method.
In the current work we demonstrate how gamma radiation induced synthesis can be implemented to produce metal (Ag, Cu, Ni) and metal oxide (Cu2O, Co3O4, CeO2) nanoparticles having narrow size distribution for different applications. The nanomaterials are produced both free standing and on solid supports. Metal nanoparticles are synthesized using the reductive route while metal oxide particles are produced using both oxidative and reductive routes [1, 2].
1. C. Dispenza, N. Grimaldi, M. A. Sabatino, I. L. Soroka and M. Jonsson, J. Nanoscale and Nanotechnol., 2015, 15, 3445-3467.
2. I. L. Soroka, N. V. Tarakina, A. Hermansson, L. Bigum, R. Widerberg, M. S. Andersson, R. Mathieu, A. R. Paulraj, Y. Kiros. Dalton Trans. 2017, 46, 9995-10002.
9:30 AM - NM04.01.04
Photoelectron Spectroscopy Investigation of GaN/Si Heterostructures for Photoelectrochemical Water Splitting
Srinivas Vanka1,2,Elisabetta Arca3,Glenn Teeter3,Zetian Mi2
McGill University1,University of Michigan2,National Renewable Energy Laboratory3Show Abstract
Surface, interface, and bandgap engineering play a pivotal role for designing tandem photoelectrodes for photoelectrochemical water splitting to potentially realize solar-to-hydrogen efficiencies >20%. III-nitride semiconductors, e.g. GaInN, have emerged as one of the most promising materials to realize high efficiency photoelectrodes: their fundamental bandgap can be varied across nearly the entire solar spectrum by changing the alloy compositions and the band edge positions straddle water oxidation and reduction potentials under visible light irradiation. In this context, we have performed, both theoretically and experimentally, a detailed investigation of the structural, electronic, and photoelectrochemical properties of Ga(In)N/Si heterostructures. Detailed X-ray photoelectron spectroscopy (XPS) measurements reveal that the conduction band edge of GaN and Si are near-perfectly aligned, which enables efficient extraction of photo-generated electrons from the underlying Si wafer to GaN nanowires. Band diagrams were constructed from the measured valence band minimum (VBM) and the observed core-level shifts between different thickness GaN/Si samples. Deposition of 2-3 nm of GaN evidently passivates the Si surface and induces a small amount of upward band bending (BB). The interfacial valence-band offset calculated from measured VBMs and core-level shifts was 2.52±0.1 eV. This value, in combination with the individual band gaps of Si and GaN, leads to a conduction band offset of -0.22±0.1 eV, where the negative sign indicates that the CBM of GaN is lower than that of Si. It is to be noted that n+-(In)GaN acts like a hole blocking layer which helps in charge carrier separation and thereby reduce the surface recombination of the photo-generated carriers. With the incorporation of Pt co-catalyst nanoparticles on Ga(In)N surface, we have demonstrated solar water splitting on Ga(In)N/Si photocathode with a maximum current density of >35 mA/cm2 and an applied bias photon-to-current efficiency >10% in 0.5 M H2SO4 under AM1.5G one-sun illumination. This work shows the use of GaN nanowires as a multi-functional protection layer as well as excellent charge extraction of the photogenerated electrons from the underlying Si wafer.
9:45 AM - NM04.01.05
Structure and Reactivity of Zinc Oxide Nanoparticles—A DFT Study
Takat Rawal1,2,Loukas Petridis1,2
University of Tennessee1,Oak Ridge National Laboratory2Show Abstract
Zinc oxide (ZnO) nanoparticle, an active ingredient of bactericides, has potential applications in treating citrus greening disease owing to its unique properties. Here, employing density functional theory we study the structures and reactivity of sub-nanometer-sized ZnO nanoparticles. Examination on the propensity of binding of water, urea, salicylic acid and citric acid molecules to the surface of ZnO nanoparticle (diameter ~14Å), indicates that the molecules bind strongly at Zn atoms at the nanoparticle edges. Strikingly, the binding of urea, salicylic acid and citric acid through their O (O=C) atoms at the Zn sites can be traced to the electronic structures. We also investigate the solvation effects on the binding characteristics of these molecules. Finally, we compare the structures and energetics of molecules adsorbed on the nanoparticle with those on extended ZnO(10-10) surface, and find that the edge Zn sites of the nanoparticles are more active than the surface Zn sites of the extended surface. Overall, our results provide insights into the reactivity of ZnO nanoparticle in different local environments, and may offer guidelines to design the ZnO-nanoparticle-based material as an antibacterial agent for agricultural applications.
*This work is supported by USDA NIFA under grant FLAW-2014-10120.
10:30 AM - NM04.01.06
Hybrid Nanomaterials and Their Applications in Energy and Water Areas
Pei Dong1,Yongjie Zhan2,Jun Lou3
George Mason University1,Northwest University2,Rice University3Show Abstract
Water and energy are two of the world’s most valuable resources. In the near future, as the industrial sector expands, demand for water and energy will be even greater than it is today. Recently, advanced materials have been widely implemented in energy and water areas. Here, hybrid nanostructures composing of graphene-like film and bamboo-like carbon nanotubes have been synthesized in a simple, one-pot, catalyst-free chemical vapor deposition process. Pre-sputtered carbon coating on a copper substrate is considered as the key factor contributing to the final morphology. Furthermore, this hybrid nanostructure product has been shown to be a potential alternative material in solar cell and water desalination applications for sustainability.
10:45 AM - *NM04.01.07
Smart Gel-Based Materials from Design to Application via Organic-Inorganic Hybrid Technology
Meifang Zhu1,Kai Hou1,Peiling Wei1,Tao Chen1,Mengge Xia1,Zhouqi Meng1
State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University1Show Abstract
Smart gels-based materials can response external stimulus, such as temperature, pH value, light, electric, magnetic etc., via significant volume phase transition, have attracted a great amount of attentions.1 Recently, organic/inorganic hybrids have been developed as a novel platform for design of gels-based materials with diverse scales and dimensions, showing multi-functions to broad their applications in smart sensing and biomedical fields. Here, combing our long-term research, series of organic-inorganic hybrid gels-based materials with diverse dimensions to meet practical applications requirements have been designed and prepared. In details, we prepared zero-dimensional (0D) nanogels, functionalizing with photothermal agents and anti-cancer drugs to deal with cancer.2-4 As for 1D fiber, we obtained hydrogel fibers continuously with high efficiency based on a novel dynamic-crosslinking-spinning technology, the hydrogel fiber could be functionalized with conductive agents using a subtle coaxial spinneret, provide promising candidate for artificial nerves.5 Furthermore, several 3D smart bulk hydrogels were synthesized by in-situ introduction of functional nanoparticles into hydrogels, which could be used in fields of sensors including micro-channel valves and temperature switches.6-9
Acknowledgement: This work is financially supported by National Key Research and Development Program of China (2016YFA0201700/2016YFA0201702), Project of Shanghai International Science and Technology Cooperation Fund (14520710200) and Program for Changjiang Scholars and Innovative Research Team in University (T2011079, IRT_16R13), and the Program of Talents of Discipline to University (111-2-04), and Innovation Program of Shanghai Municipal Education Commission (2017-01-07-00-03-E00055).
1 Jones, C. D.; Steed, J. W. Chem. Soc. Rev. 2016, 45, 6546.
2 Chen, Z. G.; Wang, H. P.; Zhu, M. F. Advanced Materials, 2015, 28, 245.
3 Chen, Z. G.; Zhu, M. F. Adv. Mater. 2013, 25, 2095.
4 Chen, Z. G.; Zhu, M. F.; Hu J. Q. Adv. Mater. 2011, 23, 3542.
5 Hou, K.; Zhu, M. F. Macromol. Rapid Commun., 2016, 37, 1795.
6 Zhang, Q.H.; Zhu, M. F. Carbon, 2011, 49, 47.
7 Xia, M.; Zhu, M. F. Aust. J. Chem., 2014, 67, 112.
8 Liu, Y.; Zhu, M.F. Soft Matter, 2012, 8, 3295.
9 Xia, M.; Zhu, M. F. Macromol. Rapid Commun., 2015, 36, 477.
11:15 AM - NM04.01.08
Nanostructured Devices and Catalysts for the Solar-Driven Reduction of CO2 to Fuels
Marcel Schreier1,Michael Graetzel2,Yogesh Surendranath1
Massachusetts Institute of Technology1,Ecole Polytechnique Federale de Lausanne2Show Abstract
CO2-derived fuels present an attractive way towards a sustainable energy system. Mimicking natural photosynthesis by synthesizing carbon-based energy carriers using renewable energy allows for closing the anthropogenic carbon cycle and therefore represents an attractive way to store intermittent power, a challenge that has not yet found a satisfying solution.
Using solar power as the energy source for fuel synthesis will require large surfaces of absorbers and efficient catalysts, which should be fabricated from abundant materials. In this context, we show the application of cheap and scalable Cu2O photocathodes in combination with molecular rhenium catalysts, both in solution and covalently bound to the nanostructured photoelectrode surface. Both systems feature substantial photocurrents and photovoltages, demonstrating protected Cu2O photocathodes as viable candidates for solar-driven CO2 reduction processes.
Moving from organic solvents into aqueous systems, we demonstrate the unassisted and sustainable splitting of CO2 into CO and O2 using perovskite photovoltaics as light absorbers and nanostructured gold and IrO2 as catalysts, reaching an efficiency of 6.5 %. Building up on this work, we show how ALD modification of CuO nanowires can lead to a bifunctional and low-cost catalyst both for CO evolution from CO2 and for the oxygen evolution reaction. By ALD modification, the wide product distribution of Cu-based catalysts could be narrowed to yield predominantly CO. Investigations into the microkinetics on these electrodes indicate that the selectivity change is due to the suppression of H2 evolution, while the rate of CO production remains similar. Together with the use of a bipolar membrane, allowing for separating product gases while maintaining a sustained pH gradient, we used these electrodes demonstrate long-term solar CO production at an efficiency of 13.4 %, driven by a single 3-junction photovoltaic.
Going beyond the production of CO, a novel approach was used to gain insight into the mechanism of hydrocarbon formation at copper electrocatalysts. Studying this process in nonaqueous electrolytes at low temperatures allows for fine-tuned control of the proton donor and the CO binding strength, enabling activation-controlled kinetic studies over an extended parameter range. From these measurements, we are able to show that the rate of methane and hydrogen formation is governed by the competition of CO and H for surface sites while ethylene formation remains weakly impacted by this effect.
The presentation illustrates the pathway to ever more insight and to efficient catalysts and devices for the reduction of CO2, first to CO and subsequently to hydrocarbon fuels such as methane and ethylene.
11:30 AM -
RAPID FIRE PRESENTATION
NM04.02: Synthesis and Nanomanufacturing II
Maia Mombrú Frutos
Monday PM, November 26, 2018
Sheraton, 2nd Floor, Back Bay C
1:45 PM - NM04.02.02
Etched Metal Superhydrophobic Surfaces for Enhanced Condensation
Soumyadip Sett1,Kalyan Boyina1,Kazi Fazle Rabbi1,Bassel Abu Jabal1,Justin Olson1,Longnan Li1,Nenad Miljkovic1
University of Illinois1Show Abstract
Inspired from natural surfaces such as lotus leaves, water strider legs, the Namib desert beetle, and geckos’ feet, the past few decades have seen significant research and development in the design and manufacturing of water repellent or superhydrophobic surfaces. For superhydrophobicity, surfaces need to be fabricated in two steps, initially creating micro/nanostructures, thereby providing roughness to the primary substrate, followed by the deposition of a low surface energy coating. The low surface energy leads to higher advancing and receding contact angles with water droplets, lower contact angle hysteresis, and hence easy droplet removal, promoting dropwise condensation and enhancing heat transfer. Recent studies have focused on chemical oxidation of metallic surfaces to form conformal micro/nanoscale structured metal oxide layers at the solid-air interface. The process is usually self-limiting, with both the oxide layer thickness and structure length scale ranging from 10 nm to 100 µm. Despite enabling efficient dropwise condensation, the metal oxide layers create a significant conduction parasitic thermal resistance due to their lower thermal conductivities (around 10 W/m.K) when compared to their pure metal counterparts (around 100 W/m.K). Furthermore, the application of metal oxide structures for industrial applications remains a challenge due to their poor durability. Here, we develop micro/nanostructured surfaces via direct electrolytic etching of metals. Different length scale surface structures and roughness are obtained by controlling the etching time and supply voltage of the electrolytic process. The etched metallic structures are made of the base metal, enabling higher thermal conductivity and lower parasitic resistance. Furthermore, the uniform metallic composition of the base metal and etched structures enables greater durability from thermo-mechanical stresses. Linear abrasion tests revealed greater durability of our etched metal structures when compared to metal oxides. After coating the developed surfaces with a low energy self-assembled monolayer using vapor deposition, these surfaces show water droplet contact angles greater than 160°. Our work not only develops metal etched structured surfaces for durable condensation of steam and enhancement of condensation heat transfer coefficient, it enables a scalable manufacturing technique for durable superhydrophobicity.
2:00 PM - NM04.02.03
Periodic Step Nanostructure Evolution at the Thin Film Gold/Substrate Interface
Alex Katsman1,Linfeng Chen1,Maria Koifman Khristosov1,Cecile Saguy1,Boaz Pokroy1
Technion–Israel Institute of Technology1Show Abstract
Nanoscale step structures have attracted recent interest owing to their importance in both fundamental and applied research, for example in adsorption, in catalysis, and in directing nanowire growth. In this in situ study, self-ordered vicinal-like surface structures were obtained by annealing of thin films of gold deposited on ultraflat Si/SiO2 substrate. Annealing at temperatures ≥200 °C efficiently promoted the formation of vicinal-like structures on the inner gold/substrate interface. Gold grains near the inner surface exhibited an orientation with the  direction very close to the substrate normal. Furthermore, the step periodicity depended on the grain/substrate orientation angle. Smaller misorientation resulted in a larger average step periodicity, similar to that seen in regular vicinal surfaces of gold single crystals. Formation of low-index terraces and atomic steps at the inner gold interface (while the silica surface remains ultraflat) can be considered as a kind of solid−solid dewetting. We suggest that the formation of vicinal-like structures could be attributed to the thermally activated surface reconstruction driven by minimization of the total surface energy, which includes the gold/substrate cohesion energy and the GB energies. The process is controlled by diffusion of gold from the inner gold/substrate interface, most probably to the grain boundaries and then to the outer surface of the film. Substantial bulk diffusion across the film during annealing at 400 °C for 4 h can also provide a required mass transport from the inner to the outer surface. This work contributes to the understanding of the atomic step structure formation at the gold/substrate interface, which will be helpful in the use of vicinal-like surfaces as templates for growing of regularly spaced nanostructures. It also offers a method for the in situ investigation of both the grain orientation and the grain interface step periodicity in a given grain, and then can be utilized for further explorations of vicinal-like surfaces.
2:15 PM - *NM04.02.04
Sustainable Hydrogen Solution Enabled Through Hydrolysis with Water-Reactive Nanoporous Metals
Eric Detsi1,John Corsi1,Jintao Fu1
University of Pennsylvania1Show Abstract
Water-reactive nanostructured metals and metalloids such as nano-Mg, nano-Al, nano-Zn and nano-Si with minimum surface oxide coverage have a broad range of potential applications. They can serve as catalysts for combustion