Symposium CE
Frontiers in Nanostructured, Nanocomposite and Hybrid Functional Materials for Energy and Sustainability

Session CE-1 - Innovative Processing of Nano- and Heterostructures and Films of Functional Materials

CE-1:IL01  Low Cost Solution Processing of Nanowires for Flexible Devices
YOUNG-JEI OH, B.-W. WANG, Opto/Electronic Materials & Devices Research Center, Korea Institute of Science and Technology (KIST), Seoul, South Korea; Department of Nanomaterials Science and Engineering, University of Science and Technology (UST), Dae-Jeon, South Korea

Solution printing that is simplified process at lower temperature compared to existing electronic printing process offers a great advantage of inexpensive and large area application even on bendable, stretchable and wearable substrates. While ITO has been widely used as outstanding electrode, there are some drawbacks cannot escape. Ion-ink of Cu++, as a functional electronic ink for flexible electronics, which is environmentally friendly, low cost and can be sintered even at low temperature, was prepared. Photonic heating of ion-ink patterns were successfully achieved by IPL irradiation. Low cost ink of silver or copper nanowire and an over-coated layer of graphene oxide on the nanowires were fabricated. Large area transparent electrodes coated by silver nanowires were manufactured by continuous R2R slot-die processing, spray and bar coatings at room temperature, respectively. Long-term mechanical stability was enhanced by the GO coating on mesh-type AgNWs/PET film. PCE enhancement in solar cell are closely correlated with increased light absorption in active layer due to a light scattering and trapping effect induced by Ag nanowires. It was confirmed by a finite difference time domain simulation. The findings are expected to lead to innovative changes in flexible electronics.


CE-1:IL02  2D Oxide Nanosheets as Single-crystal Templates to Control Growth and Properties of Functional Oxides
A. TEN ELSHOF, MESA+ Institute for Nanotechnology, University of Twente, AE Enschede, The Netherlands

Metal oxide nanosheets are the oxide equivalents of graphene. They have thicknesses of 0.5-2.5 nm and lateral sizes up to tens of micrometers. Oxide nanosheets are made by delamination of layered metal oxides in water using a combination of acid-base & ion exchange reactions. Since nanosheets are 2D single crystallites with only one type of surface termination, they are versatile seed layers for growth of oriented and epitaxial functional metal oxides. Oriented perovskite-type thin films of SrRuO3, (La,Sr)MnO3, Pb(Zr,Ti)O3 and BiFeO3 have been grown on Ca2Nb3O10 and Ti0.87O2 nanosheets using pulsed laser deposition. Depending on the nature of the seed layer, either [001] or [110] oriented perovskite films were formed, and the ferromagnetic and piezoelectric properties were shown to depend on the preferential orientation of the as-grown films. The lateral sizes of the nanosheets offered another independent parameter to modulate the properties of these films further. Also anatase has been grown from aqueous solution onto different nanosheet templates, resulting in high aspect ratio anatase crystals with different external facets. The photocatalytic activity of these systems for hydrogen formation from methanol solutions was shown to depend on the nature of the exposed facets.


CE-1:IL04  Complex Composition and Structure Materials by Solution Chemistry
G. WESTIN¹, S.N. KATEA¹, M. LEIDEBORG^{1, 3}, K. LASHGARI^{1, 3}, K. JANSSON², ¹Chemistry-Angstroem, Angstroem Laboratory, Uppsala University, Uppsala, Sweden; ²Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm, Sweden; ³S-Solar, Finspang, Sweden

The development in the renewable energy areas require complex multi-functional materials of high elemental and structural complexity in sizes down to a few nano-meters, placed in optimised hierarchical architectures. These advanced structures have to be of high quality and low cost, which most probably means few and fast processing steps. Thus, it is anticipated that molecular based solution processes will be a key manufacturing technique, but for its successful utilisation there is required a detailed knowledge about the whole process from the precursor molecules, via the solution processing and heat-treatment, to the target complex materials, which is rare and hard to obtain. Using low temperature built structures and proper molecules there are great possibilities to achieve far from thermodynamically stable materials built with connection to the molecular precursor entities. Here we will describe solution processes to; complex oxide, metal and metal-ceramic composite thin- and ultra-thin films, nano-particles and sponges, and connect the final structures to the precursors and steps in-between. A wide range of techniques were used including; XRD, IR and Raman spectroscopy, SEM, TEM, XPS and TG/DSC. Some examples showing scalability of the processes will also be given.


CE-1:IL05  Low-temperature Synthesis of Metastable Materials with Anisotropic Morphology
S. BARTH, TU Wien, Institute of Materials Chemistry, Vienna, Austria

This talk will be highlighting the low temperature growth of highly crystalline, Ge1-xSnx (x=0.17 and x=0.28) as well as hyperdoped Ge with anisotropic morphology (nanowires and nanorods). All growth processes are realized at low temperatures in the temperature range 140-230 °C leading to unusually high metal incorporation in the Ge semiconductor and the formation of metastable compositions. The anisotropic structures grow either via the solution-liquid-solid (SLS) or the vapor-liquid-solid (VLS) mechanism depending on the growth conditions. Limiting factors such as precursor decomposition temperature as well as precursor composition will be discussed. The results demonstrate the incorporation of large amount of Sn in Ge1-xSnx alters the optical properties of the resulting material. In addition, a deterioration of the material in presence of metallic Sn will be also discussed. Moreover, the hyperdoping with Ga will be discussed and tremendous effects on the electrical properties of Ge nanowires can be observed. Hyperdoping results in a metallic-like behavior of the material that can withstand huge critical current densities.
These studies have been supported by the Austrian Science Fund FWF (P 28524).


CE-1:IL06  Focused-ion-beam-enabled Electroless Metal Deposition on Silicon and Fabrication of Probes for Tip-enhanced Raman Spectroscopy
MASAYUKI NISHI, Kyoto University, Kyoto, Japan

Tip-enhanced Raman spectroscopy (TERS) is an option for scanning probe microscopy. TERS provides chemical information at nanoscale spatial resolutions by using extremely enhanced electric fields of light at the metal tip apex of the probes. We recently reported a new method to form metal nanostructures area-selectively on a silicon substrate, and applies it to fabrication of TERS probes. It is a resist-free and electroless method, and does not use any of silane-coupling agents, external reducing agents for metal ions, and hydrofluoric acid. In the actual procedure for gold deposition, local areas of a silicon substrate is irradiated with a focused ion beam (FIB). Then, the FIB-irradiated substrate is exposed to a pure aqueous solution of chloroauric acid. Gold grows as follows. Silicon dangling bonds formed by FIB irradiation reduce gold ions and initiate the nucleation of gold. The nucleation of gold forms silicon/gold interfaces, and then electrons in the crystalline silicon near the interfaces reduce gold ions through the interfaces and the growing gold. We successfully grew gold nanostructures, which are responsible for localized surface plasmon resonance, at the apex of commercially available silicon AFM probes, and demonstrated TERS imaging of carbon nanotubes.


CE-1:IL07  Flexibility of Core-shell Nanostructures for Clean Energy Work
D. HC CHUA, National University of Singapore, Singapore

Carbon is highly unique in its ability to form different allotrobes, ranging from 0D, 1D to 2D materials within the same element. This gives them a wide range of unique material properties, ranging from low dimensional effects, good structural integrity, high electrical and thermal conductivity, and chemical stability. Currently, these materials are widely used as anode/cathode/conductive layers in various applications. In this talk, we will show that we can engineer various core-shell nanostructures utilising 1D and 2D carbon-based materials as the core. This leads to enhanced electrochemical performance, which can be observed in supercapacitors, HER and PEM fuel cells. A series of in-situ tests are also performed which includes accelerated degradation test and electrochemical impedance spectroscopy to validate the effectiveness and robustness of these materials. Furthermore, we will also discuss on the latest progress in finding non-noble metal electrocatalyst, such as CoP, CoSe and other materials.


CE-1:IL08  Recent Advances in the MOVPE Growth and Nano-Scale Characterization of III-V Nanowires for Photonics and Photovoltaics
N. LOVERGINE, Università del Salento, Lecce, Italy; P. PRETE, IMM-CNR, Lecce, Italy

III-V compounds nanowires (NWs) gather considerable research interests, in reason of their potential applications to novel nano-scale photonic and photovoltaic devices. Radial modulation of NW composition in the form of core-(multi)shell heterostructures promises to impact such nano-devices, but requires strict control over epitaxial self-assembly and understanding of their nano-scale electronic/radiative properties. We report on the MOVPE growth and nano-structural/spectroscopic properties of GaAs-AlGaAs core-shell and core-multishell NWs. Combination of advanced nano-characterization tools and shell growth modelling allowed us to evidence the occurrence of novel Al segregation/incorporation phenomena within the NWs and their effect on both the materials axial and radial growth. Present results will be discussed in the light of current NW self-assembly models. Besides, we present a detailed study of the NW radiative (excitonic) emission, evidencing the combined effect of strain-induced band-shift and impurity-induced electric fields. Further, high spatial resolution spectroscopic studies performed on single GaAs-AlGaAs quantum well tube (QWT) structures allowed to evidence large-scale spatial inhomogeneities (along the NW trunk) and nano-scale fluctuations of the QWT emissions.
 

CE-1:L09  Particle Sintering and Buildup of Solid-electrolyte Interfaces in APorous TiO2 Nanocrystal Electrodes
K. RETTENMAIER, J. MIGUEL JIMÉNEZ, T. BERGER, Department of Chemistry and Physics of Materials, University of Salzburg, Salzburg, Austria

Sintered nanocrystal electrodes are interface-determined materials [1]. The control and systematic manipulation of their interfacial properties therefore constitute a way toward more active materials in applications ranging from sensing to energy conversion and storage [2]. We prepared anatase TiO2 powders consisting of isolated nanocrystals by metal organic chemical vapor synthesis. After particle immobilization particle-particle interfaces were formed by carefully controlling the sintering temperature (100 °C < T < 450 °C). We characterized the structure and the morphology of the resulting nanocrystal films and studied the impact of sintering temperature on the electrical conductivity and on the electrochemical properties (charge storage capacity, charge separation efficiency) of the electrodes. Sintered nanoparticle films were processed at high vacuum conditions (p < 10-5 mbar) and contacted with aqueous electrolyte solutions via a vapor phase transfer technique. This bottom up approach allows for a controlled buildup of semiconductor/electrolyte interfaces and for studying the impact of interface composition on the photoelectrochemical properties of the electrodes.
[1] J. Bisquert Phys. Chem. Chem. Phys. 2008, 10, 49. [2] J.M. Jiménez et al. J. Am. Chem. Soc. 2016, 138, 1.


CE-1:IL10  Low Temperature Growth of Graphene with In-situ TEM Observations
MASAKI TANEMURA¹, M.I. ARABY¹, R. VISHWAKARMA¹, M.S. ROSMI², S. SHARMA¹, Y. WAKAMATSU¹, K. TAKAHASHI¹, G. KALITA¹, M. KITAZAWA³, Y. YAAKOB⁴, M.Z.M. YUSOP⁵, ¹Dept. of Frontier Materials, Nagoya Inst. of Tech., Showa-ku, Nagoya, Japan; ²Dept. of Chemistry, Faculty of Science and Mathematics, Universiti Pendidikan Sultan Idris, Tanjong Malim, Perak, Malaysia; ³Olympus Co. Ltd., Nagano, Japan; ⁴Dept. of Physics, Univ. Putra Malaysia, UPM Serdang, Selangor, Malaysia; ⁵Dept. of Materials, Univ. Tech. Malaysia, Skudai, Johor, Malaysia

Graphitized nanocarbon, such as graphene and carbon nanotube (CNT), is one of the hottest materials in nanotechnology and nanomaterials science, thus myriads of applications are expected. The subjects to be solved for realizing those applications include their controllable synthesis, namely, controllability in crystallinity, size, growth position, growth temperature and so on. In order to achieve the growth controllability, understanding of their growth process by its detailed observation in atomic dimension will be indispensable. In this talk, in situ dynamic transmission electron microscopy (TEM) observation of the synthesis of graphene and CNTs with various catalysts by solid phase reaction will be dealt with [1-4]. A challenge based on the findings in those in situ TEM observations to the graphene growth at temperatures as low as 150-250 C using novel catalysts, which are rarely used for the conventional chemical vapor deposition, will be also demonstrated [5,6].
[1] M. Z. Yusop, et al., ACS Nano 6 (2012) 9567. [2] C. Takahashi, et al., Carbon 75 (2014) 277. [3] M. Rosmi, et al., Scientific Rep., 4 (2014) 7563. [4] M. Rosmi, et al., RSC Adv., 6 (2016) 82459. [5] R. Vishwakarma, et al., Scientific Rep., 7 (2017) 43756. [6] M. I. Araby, et al., RSC Adv., 7 (2017) 47353.


CE-1:L11  Hybrid Down-converting Nano-structures for Solid State Lighting
H. MENKARA, PhosphorTech, Kennesaw, GA, USA

Achieving higher luminous efficacy in phosphor converted light emitting diodes (pcLED) requires breakthroughs in down-converting materials that provide high conversion efficiency, tunable narrow bandwidth emission, and temperature/chemical stability. While conventional bulk phosphors are currently the dominant down-converters used in high power solid-state lighting (SSL) applications, their performance is limited by intrinsic properties such as high scattering cross-sections and large emission bandwidth. On the other hand, conventional luminescent nanocrystals (e.g, quantum dots or QDs) have high self-absorption and poor thermal and chemical stability for HB LEDs. We recently demonstrated the feasibility of high brightness and stable hybrid inorganic down-converting (HID) material systems applied to blue LEDs. This was achieved by synthesizing various nano-tetrapods (NRs) that exhibit narrow-band emissions and improved optical stability. Ultimately, these materials and structures will enable a new generation of solid state lighting devices with high luminous efficacies, high color and thermal stability, and with spectral efficiency near the theoretical maximum luminous efficacy of radiation (LER), as a result of their color tunability and narrow bandwidths (FWHM < 30nm).


CE-1:IL12  Novel Routes to Non-oxide Metal-containing Nanoparticles (phosphides, carbides, oxysulfides)
S. CARENCO, Sorbonne Universités, UPMC Univ Paris 06, CNRS, Collège de France, Lab. de Chimie de la Matière Condensée de Paris, Paris, France

As bulk compounds, metal phosphide and metal carbides have been studied for decades, as they combine hardness and resistivity of ceramics with electronic and optical properties of metals and find therefore widespread application for their mechanical and magnetic properties, and more recently as catalytic materials. Metal oxysulfides were also prepared and used as pigments in the industry. Obtaining at the nanoscale the phases listed above cannot be achieved through the traditional solid-state route: synthesis performed in lower temperature range and in solution allow a much better control of the nanoparticles phase, composition and morphology. This presentation will show that the selection of the precursors, the reducing agent and the reaction medium is crucial to the success of the synthesis. Moreover, nanoparticles of small size (below 50 nm) present a high surface-to-ratio volume. As a consequence, understanding the surface state is critical in order to move forward to applications (eg. catalysis). This will be discussed using in situ spectroscopy and microscopy.
Refs: [1] S. Carenco et al., Adv. Mater. 2014, 26, 371. [2] D. Ressnig et al., Chem. Commun. 2016, 52, 9546. [3] C. Larquet et al., Inorg. Chem., 2017, 2, in press. [4] S. Carenco et al., Small 2015, 11, 3045.

 
Session CE-2 - Functional Metal Oxide Nano- and Heterostructures

CE-2:IL01  Designing Catalysts for Water-Splitting Reactions: Oxide-Oxide Bilayers as High Efficiency Photoelectrocatalysts
S. MATHUR, Inorganic and Materials Chemistry University of Cologne, Cologne, Germany

Metal oxide nanostructures with hetero-contacts and phase boundaries offer unique platform for designing materials architectures for energy harvesting applications. As viable alternative to water electrolysis, photoelectrochemical (PEC) water splitting has emerged as a competitive technology being capable of converting solar energy directly into chemical energy using stable and efficient photocatalysts for solar hydrogen production. Nanostructured metal oxides and composite materials are promising candidates for effective photoanodes, which are fabricated using CVD, PE-CVD and ALD techniques for producing multilayered electrodes as oxygen evolution reaction catalysts. Besides the size and surface effects, the modulation of electronic behaviour due to junction properties leads to modified surface states that promote selective decomposition of analytes and adsorbates. The growing possibilities of engineering nanostructures in various compositions (pure, doped, composites, heterostructures) and forms has intensified the research on the integration of different functional material units in a single architecture to obtain new photocatalytic materials. In addition, new concepts of enhancing charge transduction by surface functionalization are promising strategies to promote specific chemical interactions, however the challenge related to reproducible synthesis and device integration of nanomaterials persist. This talk will present how chemically grown and designed thin films and bilayers of different metal oxides unfold new material properties, which can be transformed into advanced material technologies.


CE-2:IL02  ZnO Particles with Hierarchical Structures and Gas Sensing Application
NORIKO SAITO, H. HANEDA, I. SAKAGUCHI; K. WATANABE, K. SHIMANOE, National Institute for Materials Science, Tsukuba, Japan; Kyushu University, Fukuoka, Japan

Zinc oxide is an n-type metal oxide semiconductor with wide-bandgap and used in electronic applications. Control of the ZnO nanostructures attracts attentions and a wide variety of ZnO morphology are observed for precipitates and thin films made by solution-based processing. We have investigated solvothermal processes to synthesize ZnO particles in a water-ethylene glycol mix solvent. We obtained ZnO spherical particles with hierarchal nanostructure. The spheres were made up of small triangular pyramid-like crystallites, which were radially aligned along the c-axis. Convergent-beam electron diffraction revealed that the surface of the spherical particles was the c(+)-plane. When the solvothermal procedure was carried out under agitation, dispersed ZnO particles were precipitated instead of spheres. The obtained particles were about 20 nm and have pyramidal shape. The particles showed an ultra-high sensor response to ethanol gas. The response value, the resistance ratio in the air and in the ethanol gas, measured at 320ºC was about 10000 to 50-ppm ethanol gas, which was the best result reported for ZnO ethanol sensors. The high gas sensing property is probably due to the unique crystal planes as well as pore structure for the pyramidal shaped ZnO particles.


CE-2:IL04  Chemical Synthesis of TiO2 and Complex Nanocrystals by Means of Colloidal Approaches
M. EPIFANI, CNR-IMM, Lecce, Italy

Titanium dioxide has become a very popular material displaying a plethora of different properties and applications. The synthesis of TiO2 nanocrystals with controlled shape, size and phase is now well established by a variety of techniques. Nevertheless, still pure TiO2 is amenable to further modifications with the aim of tailoring the properties and reactivity. In this work first the basic physico-chemical principles will be illustrated, underlying the synthesis of pure titanium dioxide nanocrystals. It will be shown that sol-gel and solvothermal processing can be suitably coupled to provide organic-dispersable titania nanocrystals in the anatase crystallographic phase. Then, the problem of tailoring the surface reactivity of titania nanocrystals will be addressed, by suitable cross-talk with heterogeneous catalysis. The resulting materials design will be introduced, consisting in titania core carrying surface deposition of V2O5, WO3 and MoO3-like layers. The chemical principles and their experimental implementation will be discussed, based on the ideas developed in the synthesis of pure TiO2 nanocrystals. The critical issue of the effective determination of structure and composition will be detailed. Finally, functional properties of the resulting materials will be discussed.


CE-2:L06  Functionalization of Oxide Banocrystals with Transition Metal Ions
M. NIEDERMAIER, University of Salzburg, Salzburg, Austria; A. GHEISI, Friedrich-Alexander-University Erlangen, Bavaria, Erlangen, Germany; J. BERNARDI, Vienna University of Technology, Vienna, Austria; O. DIWALD, University of Salzburg, Salzburg, Austria

Structure and functional properties of composite metal oxide nanoparticle systems are subject to stability and composition of related surfaces and interfaces. For vapor phase grown non-equilibrium solids, annealing induced ion diffusion provides efficient means to adjust surface composition and thus, functional properties of the material. Insights into such transformation processes are essential for both nanomaterial design and material applications at elevated temperatures. In the present contribution we will discuss properties and transformation behavior of metal oxide composites, such as Fe-Mg-O and Co-Mg-O nanoparticles, which were prepared by a hybrid chemical vapor synthesis approach using organic transition metal compounds as precursors. We used an integrated characterization approach to study structure and morphology of characteristic local structures as well as local surroundings of admixed transition metal ions. The complex evolution of the composite nanostructures as a result of annealing induced segregation and phase separation was characterized for samples with different thermal processing histories. These can give rise to a variety of material types in the range between nanostructures with bulk and surface admixed transition metal oxides to phase separated systems.


CE-2:IL08  Back Interface Random Texturing for Enhanced Light Harvesting to Achieve High-efficiency Perovskite Solar Cells
J. TOUDERT, M. KRAMARENKO, H. ZHANG, J. OSMOND, J. MARTORELL*, ICFO - Institut de Cienciès Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, Barcelona, Spain; *Departament de Física, Universitat Politècnica de Catalunya, Terrassa, Spain

Organic–inorganic hybrid perovskites are emerging as highly attractive materials to be used as active medium in solar cells. Power conversion efficiencies near 20% have already been reported in single junction planar perovskite solar cells. However, getting closer from the theoretical efficiency limit for such cells requires light management architectures to maximize the harvesting of light in the perovskite material, which is not optimal in the red-to-near infrared spectral region. Implementing such architectures without degrading the electrical properties of the cell is a challenging, yet mandatory, requirement for an effective improvement of its photovoltaic performance. Here, we demonstrate that a random texturing of the back metal/hole transport layer interface in high-efficiency planar perovskite solar cells enables plasmonic and light backscattering effects that enhance light harvesting. Such texturing, which is achieved by transfer of the natural perovskite roughness, does not affect the cell’s electrical properties. Therefore, it yields a significant increase in the short circuit current while the other photovoltaic parameters are not affected. Upon texturing, a photovoltaic conversion efficiency enhancement from 19.3% to 19.8% is demonstrated.


CE-2:IL09  Low-loss Rutile TiO2 Films for Nanophotonic Applications
S. KUPRENAITE¹, S. GRIESSE-NASCIMENTO², S. MARGUERON³, C. MILLON¹, D. RADDENZATI¹, E. MAZUR², A. BARTASYTE¹, ¹FEMTO-ST institute, Université Bourgogne Franche-Comté, ENSMM, Besançon, France; ²School of Engineering and Applied Sciences, Harvard University, Cambridge, USA; ³LMOPS Laboratory, Université de Lorraine et CentraleSupélec, Metz, France

Titanium dioxide is a promising material for integrated photonics that is considered to be ideal for applications in nonlinear optics due to its high nonlinear refractive index (30 times that of silica) matched with large transparency (for λ > 400 nm). Its high linear refractive index (2.4–2.8) enables dense on-chip integration of nanophotonic waveguides and high confinement, that produces effective nonlinearities (100,000 times that of standard silica fiber). Integrated photonic devices require high-quality films to reduce optical losses. Therefore, the structural and compositional defect concentrations were optimized to ameliorate optical quality of TiO2 films and the films with low losses were attained. Using 3D high-temperature masks and deep UV/e-beam lithography, the films were structured to fabricate waveguides with micron size features. Compact optical circuits were fabricated in the thin film/substrate heterostructures with very high refraction index contrast.


CE-2:L10  Enhancement of Oxygen Reduction Reaction (ORR) Catalytic Activity on the Modified Surface of La0.6Sr0.4Co0.2Fe0.8O3-δ by Palladium Nanoparticles
MI YOUNG OH, HAN BIT KIM, TAE HO SHIN, Korea Institute of Ceramic Engineering and Technology, Jinju-si, Gyeongsangnam-do, South Korea

Perovskite La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) have been considered as a promising electrocatalyst because of their favorable physical/chemical properties including high electronic/ionic conductivity, electrochemical activity and enhanced catalytic properties. Although LSCF exhibits relatively good catalytic activity for oxygen evolution reaction (OER), it is still low in the catalytic activity of oxygen reduction reaction (ORR) when using as electrocatalyst. So it is necessary to improve the ORR activity along with OER and bring out the bifunctional electrocatalytic activity. Among the various ORR electrocatalysts, palladium (Pd) appears to be the better substitute for Pt since they share many similar properties in addition to lower cost and abundance. In our study, Pd nanoparticles were deposited over the LSCF surface to improve the ORR activity. The electrocatalytic effect of Pd nanoparticles deposited perovskite LSCF (Pd/LSCF) was examined by various structural and electrochemical test. Increasing the weight percentage of Pd, surface area and ORR activity of the Pd/LSCF samples increases. It was concluded that the decoration of Pd over perovskite LSCF is more effective to increase the ORR activity, resulting in increasing the performance as bifunctional electrocatalyst.

 
Session CE-3 - Functional Materials and Sustainability

CE-3:IL02  Organic-inorganic Hybrid Aerogels and Xerogels with High Strength and Flexibility
KAZUYOSHI KANAMORI, Department of Chemistry, Graduate School of Science, Kyoto University, Japan

Polyorganosiloxanes, or silicones, are a traditional class of organic-inorganic hybrid materials, showing unique properties such as mechanical flexibility. In recent years, we have developed designing strategies in hydrolysis and polycondensation of organo-substituted alkoxysilanes to obtain polyorganosiloxane gels, and found that the resultant wet gels can be transformed into highly porous aerogels via supercritical drying, and moreover, into aerogel-like xerogels via ambient pressure drying due to their high mechanical strength and flexibility. In our first case, a polymethylsilsesquioxane (PMSQ, CH3SiO3/2) gel has been developed to yield a highly porous, transparent xerogel, which would offer a cost-effective process for massive industrialization of aerogel(xerogel)-based thermal superinsulators. Several other aerogels and xerogels based on polyorganosiloxane, such as polyvinylsilsesquioxane and ethylene- and ethenylene-bridged polymethylsiloxane, have been developed to further improve the mechanical properties.


CE-3:IL03  Li-ion Conductor for Future Energy Storage
LI LU, National University of Singapore National University of Singapore Suzhou Research Institute, Singapore

Current Li-ion batteries suffer from two major drawbacks although they have widely been used in many applications, one of which is low energy density about 150 to 180 Wh/kg and the second one is safety concerns. The two drawbacks are caused by format of current batteries in which organic electrolytes are used. Since organic electrolytes can be easily contaminated by moisture, and are highly flammable, they must be well sealed to avoid to contact with air. In addition, since organic electrolytes have a narrow potential window, some of high potential cathode materials are unable to be used. Therefore, nonflammable and stable electrolytes should be developed. This work reports successful development of solid oxide electrolytes with high ionic conductivity and at the same time the solid electrolyte has been used for all-solid-state batteries and Li-air batteries.


CE-3:IL04  High Conversion Efficiency Materials for Thermoelectric Applications
W. WONG-NG, C. BROWN, J. MARTIN, Q. HUANG, National Institute of Standards and Technology, Gaithersburg, MD, USA; Y. YAN, Wuhan University of Technology, Wuhan, China; Y.C. LAN, Morgan State University, Baltimore, MD, USA; Z.F. REN, University of Houston, Houston, TX, USA

In recent years, there has been a surging demand for high efficiency and environmentally friendly thermoelectric materials for energy conversion applications, including both waste heat conversion and refrigeration. The search for high efficiency materials materials has led to the development of a variety of nano-structured materials. Nano thermoelectric materials provide many advantages as compared to the bulk materials, including reduction of thermal conductivity due to grain boundary scattering. In this talk, I will give an overview about the recent advances of thermoelectric nano-research, followed by a discussion of our recent research activities in high conversion efficiency nano-structured materials, including the half-Heusler, silicon germanium, and bismuth telluride materials.


CE-3:L05  Nano-catalyst Infiltration Enhancement of Porous Solid Oxide Fuel Cell Electrodes Using Catechol Surfactants
O. OZMEN, K. SABOLSKY, J.W. ZONDLO, E.M. SABOLSKY, West Virginia University, Morgantown, WV, USA; S. LEE, G. HACKETT, H. ABERNATHY, US Department of Energy, National Energy Technology Laboratory, Morgantown, WV, USA

The objective of this work was to investigate an aqueous-based infiltration process to efficiently insert nano-catalyst within the anode of solid oxide fuel cells (SOFC). The presentation will discuss the use of catechol-based surface modifiers, such as poly-dopamine, poly-epinephrine and poly-caffeic acid. In this work, these bio-adhesive surfactants were used to reduce surface tension, and also to control the chelation and deposition kinetics. The formation kinetics of the adhered surfactant and chelated nano-CeO2 electrocatalyst layers were initially studied using atomic force microscopy (AFM) on planar electrode and electrolyte substrates; this was completed before the method was applied to the porous SOFC electrodes. Experiments showed that tuning immersion time and solid loading induces nano-catalyst decoration from discrete particles to film formation onto the planar substrates. The optimal protocols were applied to impregnate anode-supported SOFC button cells. The electrochemical performance and the stability of the infiltrated anode-supported SOFCs were measured over 300 h and the performance was correlated to the decoration of the nano-catalyst impregnated electrodes. The developed impregnation protocol resulted in >20% increase in power density at 750 °C.


CE-3:L08  CO2/H2O Thermochemical Splitting on Porous SiOC Nanocomposites Decorated with 1D Catalytic Nanostructures
AITANA TAMAYO¹, B. GARCIA²; E. CASADO³, ¹Ceramics and Glass Institute, CSIC, Madrid, Spain; ²Universidad Rey Juan Carlos, Madrid, Spain; ³Universidad Politecnica Madrid, Madrid, Spain

The growing demand on sustainable fuels has motivated the re-emergence of the thermochemical splitting of gasses at high temperature. CO2 and H2O splitting occur in a two-stage process that involve catalyzed redox reactions at temperatures beyond 1400 0C. Up to now, only CeO2 and perovskite-derived materials have been reported to be candidate materials for a large scale implementation of thermochemical catalysts for syngas production. We have produced mesoporous ceramic nanocomposites whose surface has been decorated with 1D nanostructures of the thermocatalyst. The support was composed by a SiOC matrix synthesized either through the conventional polymer-derived ceramic route whereas the thermocatalysts oxides were added at different stages during the synthesis. Raman, FTIR and 29SiNMR spectroscopies have been used for the structural characterization whereas textural, energetics and surface characteristics have been analyzed by SEM, TEM and N2 adsorption techniques. The evolution of CO and H2 during the thermochemical as well as the enthalpy changes occurring during reaction were inferred from the analysis of the gases emitted at the outlet of a thermobalance feeded with CO2 and H2O(v).


CE-3:IL09  Composite Nanostructures for High-efficiency Sunlight Harvesting
A. VOMIERO, Department of Engineering Science and Mathematics, Lulea University of Technology, Lulea, Sweden

Charge dynamics (i.e. charge generation, dissociation and collection) plays a critical role in several advanced applications based on composite nanosystems, including solar energy, water splitting, nanothermometry. In most of them, semiconducting nanocrystals exhibiting quantum confined effects (quantum dots, QDs) act as light absorbing materials, which are able to generate excitons as a consequence of photon absorption. Managing the photogenerated charges enables the exploitation of different physico-chemical processes, including charge separation and collection in photoelectrochemical systems for energy conversion or tuning photoluminescence properties in luminescent nanoprobes. Key element for driving the processes to targeted applications is the modulation of composition and size of the nanomaterials, which determines the final electronic band structure of the composite systems and its functional properties. We will illustrate different examples of composite systems, targeted for specific applications. (i) “Giant” composite core-shell QDs, (ii) Near-infrared QDs with increased Stokes shift, (iii) Composite TiO2 mesoporous film sensitized by “giant” QDs. We will discuss possible strategies to tailor the optical features of the different systems toward targeted applications.


CE-3:IL10  3D SEM Analysis of Nanostructured Materials prior to Morphological Characterization of Adipose Tissue
R. SKAUDZIUS, E. GARSKAITE, A. KAREIVA, Institute of Chemistry, Vilnius University, Vilnius, Lithuania

The aim of this study is to extrapolate, measure and interpret 3-dimensional sample data out of the SEM images, taken from different angles. The silver orthophosphate nanoparticles synthesized by solution-based synthesis were selected as model materials for the spatial 3D surface reconstruction. Ag3PO4 tetrapod crystals were synthesized via the precipitation method at room temperature mixing aqueous solutions of NH4H2PO4 and AgNO3. Obtained yellow crystals were mixed with a magnetic stirrer for 5 min. After decantation crystals were three times washed with distilled water and then left for 48 h in the dark to dry. The developed methodology of 3D surface reconstruction was used for 3D characterization of adipose tissue samples taken from volunteer obese patients. The obtained results provided information about structural composition of adipose tissue layers in human body, as well as main microstructural features. It was demonstrated that such characterization of adipose tissue is an essential step for the possible prediction of appearance of symptoms of different diseases.
This work was supported by a grant SEMAT (Registration No. SEN-16014) from the Research Council of Lithuania.


CE-3:IL11  Flux Crystal Growth Concept as New Approaches to Material Synthesis and Design: A Challenge for All-solid-state Lithium Ion Batteries
KATSUYA TESHIMA, NOBUYUKI ZETTSU, Center for Energy and Environmental Science, Shinshu University, Nagano, Japan

All-solid-state lithium ion rechargeable batteries (LIBs) with higher energy density are indispensable for next-generation energy storage devices. Now, we have tried to control and design the interface and prepare materials for all-solid-state LIBs basing on flux growth technique. Flux growth is a kind of liquid phase crystal growth technique, in which molten metals and molten metal salts are used as solvents. Characteristic features of flux-grown crystals are high-quality without thermal strain, idiomorphic shape with specific crystal plains, and controlled shape and size. Various kinds of active materials (for positive and negative electrodes) and solid electrolytes for all-solid-state LIBs have been successfully grown by common flux method. In addition, we have developed a flux method to fabricate crystal layers and crystal interfaces (i.e., multilayers) with good interfaces, which is named "flux coating method". Herein, we will present the fabrication of crystal particles and layers by our flux innovation method and their electrochemical properties.
Our research is financially supported by JST-CREST, JST-ALCA and KAKENHI (25249089).


CE-3:L12  Ultra-long Vertically Aligned Lead Titanate Nanowire Arrays for Energy Harvesting in Extreme Environments
A. NAFARI¹, C.C. BOWLAND², H.A. SODANO^{1, 3}, ¹Department of Aerospace Engineering, University of Michigan, Ann Arbor, MI, USA; ²Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA; ³Department of Material Science Engineering, University of Michigan, Ann Arbor, MI, USA

Recent research has shown that nanowire arrays can be fabricated into power harvesting devices that convert ambient vibrations to electrical power. These devices, however, are limited to low temperature environments due to material constraints. To solve this problem, this paper offers a route to obtain a nanowire energy harvester that is capable of operating at extreme temperatures. This is achieved by developing a method to synthesize vertically aligned arrays of ultra-long lead titanate nanowires and fabricating them into an energy harvester. Performing power characterization measurements of the device in a temperature-controlled environment illustrates useful power generation at temperatures up to 375 °C. This work offers a new method for the fabrication of extreme temperature device thereby offering a significant advancement in the field of energy harvesting by demonstrating energy production in extreme environments where previous systems would fail.