bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrochemical Preparation of Nanostructured Silicon from Rice Husks As a Sustainable Source for High Performance Anode in Secondary Lithium Ion Battery
Authors: Wu Ding Chou , Wu Shu-Chi , Ai Yuanfei , Chueh Yu-Lun 
Published: February 2020

Silicon is one of the most promising anode material candidates for lithium ion batteries because of its high specific capacity (3579 mAh/g), which is ten times higher than existing graphite anodes. One of the most important issues toward commercialization is the high cost of nanostructured silicon related to the complex fabrication amd expansive raw materials. In this work, we demonstrate the recycling of pure silicon nanoporous particles from rice husks (RHs) directly, which is an abundant agricultural byproduct (108 tons/year) in worldwide. Besides, the massive amount of RHs has unique nanoporous structure on the RHs to preform the function as protection and ventilation. In the first step of our experiment, the metal ions in the RHs by HCl leaching were removed and then incinerate the leached RHs to produce silica with nanostructure. Next step, we convert the silica to silicon by electrochemical reduction method, which is a potential process for large scale reduction in a relative low tempareture compared with conventional carbothermal reduction. Owing to the nanoporous nature, these recovered silicon nano-particles show high performance as lithium ion battery anodes, with high reversible capacity and long cycle life. Recycling RHs as the source of silicon, this work presents a process to produce Si based Li-ion battery with cost effective, energy-efficient, green, and potential of large scale synthesis in industry.
Key words: rice husk, electrochemical reduction, Li-ion battery
Oxidation-Reduction Potential Control for One Step Synthesis of Cu-Pt Core-Shell Nanoparticles
Authors: Nakamoto Tatsuichiro , Tsuchida Shuzo , Seki Ryohei , Ueyama Yasuhiro , Yokoyama Shun , Takahashi Hideyuki , Tohji Kazuyuki 
Published: February 2020

Polymer electrolyte fuel cells (PEFCs) are promising power source because of their high power generation efficiency and low environmental pollution. However, PEFCs contain precious platinum catalyst in cathode and this leads to be expensive. Thus, PEFCs have to reduce the catalyst cost to be used more widely. In order to decrease the amount of platinum in the cathode, core-shell structured nanoparticles have been tried to synthesize. Core-shell structured nanoparticles mean, for example, Pt nanoparticles whose core is displaced by copper.
However, most of the synthesis methods of Cu-Pt core-shell nanoparticles require high energy and multiple processes. To cut the cost of PEFCs fundamentally, low cost synthesis method of core-shell nanoparticles needs to be developed. Therefore, in this study, one step synthesis method of Cu-Pt core-shell nanoparticles was researched under a mild condition such as aqueous solution of room temperature and atmospheric pressure.
Although the mild condition can cut the process cost, there are several problems. Therefore, possibility to synthesize Cu-Pt core-shell nanoparticles on the mild condition have to be evaluated before trying one step synthesis. Carbon supported Cu nanoparticles were synthesized as the first step. In the second step, the surface of the Cu nanoparticles was displaced by platinum, then Cu-Pt core-shell nanoparticles were synthesized on the mild condition in two steps.
To synthesize Cu-Pt core-shell nanoparticles in one step, oxidation-reduction potential (ORP) of metal complexes was calculated and controlled. Generally, ORP of Pt is higher than that of Cu and this leads to form Pt core Cu shell structure when Pt and Cu are reduced together. To achieve Cu core Pt shell structure, ORP calculation technique was developed and the synthesis condition which can invert the ORPs of Pt and Cu was found. Therefore, one step synthesis of Cu-Pt core-shell nanoparticles was performed on this condition and several properties of low cost PEFC cathode catalyst were measured. Detailed results will be shown in our session.
Two Different Carbon Nanotube-Based Non-Pt Fuel Cell Catalysts with High Performance and Durability
Authors: Yang Jun , Cheng Junfang , Nakashima Naotoshi 
Published: February 2020

Development of non-Pt-based electrocatalyst for fuel cells and batteries with high performance, durablity, and scalability is a strong social demand for the next-generation eco-friendly energy society[1-3].
In this meeting, we summarize our recent studies on i) development of a carbon nanotube (CNT)-based two different non-Pt type fuel cell catalysts, i.e, one is pristine multi-walled carbon nanotube/iron phthalocyanine hybrids with a well-defined nanostructure that show excellent efficiency and durability for oxygen reduction reaction[2], and the other is a decorating unoxidized-carbon nanotubes with homogeneous Ni-Co spinel (and related) nanocrystals that show superior performance for oxygen evolution/reduction reactions[3].

References

[1] T. Fujigaya, N. Nakashima, Adv. Mater., 2013, 25, 1666-1681.
[2] J. Yang, F. Toshimitsu, T. Fujigaya, N. Nakashima, J. Mater. Chem. A, 2017, 5, 1184-1191
[3] J. Yang, T. Fujigaya, N. Nakashima, Sci. Rep., 2017, 7, art.no.45384.
Carbon Nanotubes for Flexible Perovskite Solar Cells
Authors: Maruyama Shigeo 
Published: February 2020

Single-walled carbon nanotubes (SWNT), graphene, and fullerene (C60 and PCBM) would be very efficiently used in lead halide Perovskite solar cells. A film of SWNTs or graphene can be flexible and stretchable transparent-conductive layer. At the same time, this film can be carrier-selective layers, i.e., electron-blocking-layers or hole-blocking-layers. Based on our experiences of using nanotube films for CNT-Si solar cells and organic polymer solar cells [1,2], we have explored the application of SWNT films for organic-inorganic perovskite solar cells. We have demonstrated the replacement of ITO in inverted-type perovskite solar cells, SWNTs/PEDOT:PSS/CH3NH3PbI3/PCBM/Al [3]. The flexible application on polyethylene terephthalate (PET) is also demonstrated [3]. With the improved perovskite structure, a film of carbon nanotubes or graphene can be practical replacement of ITO for the flexible transparent electrode of inverted perovskite solar cells [4].
Replacement of electron-blocking-layer and metal electrode in normal-type perovskite solar cells is demonstrated as well. Those devices can have comparable PCE as the conventional design with organic electron-blocking layer and top metal electrode. The normal-type perovskite solar cell, composed of ITO/C60/CH3NH3PbI3/SWNTs, can achieve a PCE of 17 % with spiro-MeOTAD as dopant to SWNTs [5]. This structure with a perovskite layer sandwiched by C60 and SWNTs can lead to the solar cells without hysteresis and with much improved air-stability [5]. The effective passivation of the degradation of perovskite material by moisture can be achieved with C60 and SWNTs [5]. More recent configuration is using a film of SWNTs for both anode and cathode electrode [6]. The new physical understanding of band alignment must be discussed based on the demonstrations of efficient carrier selective layers with these dry-deposited SWNTs which are composed of metallic and semiconductor nanotubes.
Part of this work was supported by JSPS KAKENHI Grant Numbers JP25107002 and JP15H05760.
References:
[1] I. Jeon, K. Cui, T. Chiba, A. Anisimov, A. Nasibulin, E. Kauppinen, S. Maruyama, Y. Matsuo, J. Am. Chem. Soc., 137, 7982 (2015).
[2] I. Jeon, C. Delacou, A. Kaskela, E. I. Kauppinen, S. Maruyama, Y. Matsuo, Sci. Rep. 6, 31348 (2016).
[3] I. Jeon, T. Chiba, C. Delacou, Y. Guo, A. Kaskela, O. Reynaud, E. I. Kauppinen, S. Maruyama, Y. Matsuo, Nano Lett. 15, 6665 (2015).
[4] I. Jeon, J. Yoon, N. Ahn, M. Atwa, C. Delacou, A. Anisimov, E. Kauppinen, M. Choi, S. Maruyama, Y. Matsuo, J. Phys. Chem. Lett., 8 (2017), 5395.
[5] N. Ahn, I. Jeon, J. Yoon, E. I. Kauppinen, Y. Matsuo, S. Maruyama, M. Choi, submitted.
[6] I. Jeon, S. Seo, Y. Sato, C. Delacou, A. Anisimov, K. Suenaga, E. I. Kauppinen, S. Maruyama, Y. Matsuo, J. Phys. Chem. C, (2017), online [DOI: 10.1021/acs.jpcc.7b10334].
Improvement of ORR Catalyst Layer with Highly Graphitized CNF in PEMFC
Authors: Chung Sunki , Lee Jae Kwang , Lee Jaeyoung 
Published: February 2020

Polymer electrolyte membrane fuel cell (PEMFC) is regarded as a promising power source with the advantages of high power density and low operating temperature. However, there still remains water management problem. Water flooding is a phenomenon that the pores of the catalyst on gas diffusion layer are filled up with the excessive water produced near cathode side. And the pathway of oxygen (or air) could be blocked leading to the acceleration of the mass transfer limitation and degradation of durability because of the carbon corrosion reaction between carbon and water at cathode. Therefore, it is important to remain the right amount of water in membrane electrode assembly to keep the reaction working smoothly. In recent investigations,1,2 various types of catalyst layer structure have been studied in order to keep a proper humidity level in membrane electrode assembly (MEA) and reduce the oxygen transport resistance.
In this study, we incorporate a highly graphitized carbon nanofiber (CNF) into cathode catalyst layer for improvement mass transfer in PEMFC, and found out that graphitic CNF might serve as a pathway of water drainage and also diminish the ohmic losses due to the improved electrical conductivity of the electrode.
References

J. Joo, M. Choun, K. Kim, S. Uhm, Y. D. Kim and J. Lee, Curr. Appl. Phys., 14, 1374 (2014).

M. Choun, D. Nauryzbayev, D. Shin and J. Lee, Catal. Today, 262, 155 (2016).
Photodynamics at the Heterojunction between Semiconducting Single-Walled Carbon Nanotubes and Perylene Diimide Electron Acceptors
Authors: Kang Hyun Suk , Sisto Thomas J , Peurifoy Samuel , Zhang Boyuan , Ferguson Andrew John , Nuckolls Colin , Blackburn Jeffrey L. 
Published: February 2020

Semiconducting single-walled carbon nanotubes (s-SWCNTs) have been intensively studied in optoelectronic applications due to several advantages such as band gap tunability, high charge carrier mobility, and low internal reorganization energy. However, the fundamental aspects of exciton dissociation at heterojunctions between s-SWCNT and electron acceptors still remain elusive. Here, we investigate the detailed photodynamics at the heterojunction between (6,5) SWCNTs and perylene diimide (PDI) based electron acceptors. While a number of studies have demonstrated efficient charge transfer at interfaces between s-SWCNTs and fullerenes, as well as s-SWCNT-fullerene photovoltaic devices with high internal quantum efficiencies, studies paring s-SWCNTs with non-fullerene acceptors are rare. PDI-based electron acceptors have several potential advantages over fullerene acceptors such as broader absorption, cheaper cost, higher robustness, and greater spectral tunability.
Two novel PDI-based electron acceptors were synthesized and coated on (6,5) SWCNT films to form donor-acceptor heterojunctions. The PDI-based electron acceptors are hPDI2-pyr-hPDI2, where pyrene (electron donor) is covalently connected to PDI oligomers (hPDI2), and Trip-hPDI2, where hPDI2 is connected to each side of triptycene. The steric hindrance from these acceptors prevents excessive aggregation, which has been a significant problem for PDI-based electron acceptors. Transient absorption studies reveal that the photoinduced electron/hole transfer at the (6,5)/PFO-bpy – PDI-based acceptor heterojunction occurs, and the separated charges live longer than 1.5 μs. For the photoinduced electron transfer from (6,5) SWCNTs to PDI-based acceptors, the electron transfer to hPDI2-pyr-hPDI2 occurs more efficiently than to Trip-hPDI2, and it is attributed to weaker electron transfer driving force for Trip-hPDI2 due to its higher LUMO level than that of hPDI2-pyr-hPDI2. Charge transfer across these s-SWCNT/PDI interfaces will be compared to the more commonly studied SWCNT/C60 interfaces.
These fundamental photophysical studies provide insight into how different electron acceptor materials can impact the s-SWCNT heterojunction energetics and how the energetics impacts the kinetics of exciton dissociation and charge recombination. The results help to inform design strategies for s-SWCNT-based solar photoconversion systems.
Tunable Surface Modification of Mesoporous Carbon Nanoparticles for Polysulfide Trapping in Lithium-Sulfur Batteries
Authors: Murphy Ian Alexander , Li Yun , Jang Sei-Hum , Yang Jihui , Jen Alex 
Published: February 2020

Lithium-Sulfur (LiS) batteries are a front runner for next-generation secondary battery systems. This is partially due to the low cost, relative abundance, and environmentally benign nature of their active materials, but arguably most important is the order of magnitude increase in theoretical specific capacity of LiS cells compared to current state of the art lithium-metal oxide systems (~1,600 mAhg-1 vs ~160mAhg-1, respectively). Despite these inherent benefits, the commercialization of LiS systems has been impeded by a rapid loss of capacity upon repeated cycling due to the complexities of lithiation and delithiation at the carbon/sulfur composite cathode.
During discharge, elemental sulfur is sequentially reduced to lithium sulfide following the reaction S8 + 16Li+ + 16e-→ 8Li2S, where intermediates Li2S(8-2) are formed, their length depending on depth of discharge. Long-chain lithium polysulfides (LiPS), Li2S(8-4) are highly soluble in organic electrolytes and, once solvated, will migrate to the lithium metal anode. This leads to permanent capacity loss and internal shorting via lithium polysulfide redox shuttling. To combat this limitation, extensive efforts have been focused on trapping long-chain LiPS by both: 1. physically confining them in mesoporous carbons, and 2. chemically inducing electrostatic attractions with electron rich heteroatoms on the cathode.
In this work we not only aim to find synergy between these two approaches, but also investigate the potential for doubling the binding energy of electrostatic interactions by covalent tethering of long chain LiPS to the cathode surface via reversible di-sulfide bonding. Through a highly tunable one-step reaction, we functionalize mesoporous carbon surfaces with aromatic small molecules using in-situ generation of diazonium radicals. The flexibility of our approach allows for the introduction of a wide variety of surface functionality, and thus a platform to broaden our understanding of cathode/electrolyte interactions.
Our current progress focuses on the spectroscopic, physical, and electrochemical characterization of a thiophenol terminated carbon. Through this work we have demonstrated not only successful modification of carbon particles, but an ability to control the density of modifier groups on the surface. In conjunction with finding an optimal concentration of surface modifiers, we investigate the role of modifiers and carbon pore size in modulating the kinetics and capacity retention of LiS cells. By optimizing pore-size and modifier concentration, we have drastically increased the cycle life of our devices, which maintain >900 mAhg-1 over 150+ cycles at 0.1C. We hypothesize that the mechanism responsible for this improvement is a reversible covalent interaction based on electrochemical measurements, which indicate a concentration-dependent shift toward solid-phase reaction pathways.
(Invited) Near Infrared Chemical Imaging of Cellular Communication Using Carbon Nanotubes
Authors: Meyer Daniel , Mann Florian , Polo Elena , Hagemann Annika , Herrmann Niklas , Kruss Sebastian 
Published: February 2020

Intercellular chemical communication proceeds with both spatial and temporal components. A very prominent example is neurotransmitter release from neurons. But so far there are no analytical tools available to detect release and propagation of signaling molecules on small length scales and fast time scales. We have developed fluorescent nanosensors to monitor interactions of cells with their environment e.g. for chemical imaging of small molecules released by cells.
For that purpose we used near infrared (nIR) fluorescent single-walled carbon nanotubes (SWCNTs) and chemically rendered them selective for small signaling molecules such as the neurotransmitter dopamine. When dopamine binds the quantum yield of the sensors increased by up to 400 % and we were able to report single dopamine binding events. Parallel imaging of many of those sensors provides a nIR image (900 nm -1300 nm) of the dopamine concentration around cells. Furthermore, we used a stochastic kinetic Monte-Carlo simulation to predict the collective image of many sensors and how on and off rate constants affect the spatial and temporal resolution of this approach. This technique was used to image hot spots and directionality of dopamine release from neurons and other cells. We observed localized, unlabeled release sites that correlate with membrane curvature and cell morphology.
We furthermore tailored SWCNTs to bind cell surface receptors such as integrins to monitor and investigate cell adhesion and migration on surfaces. These results illustrate how to use fluorescent nanosensors for quantitative chemical imaging of complex biological processes.
(Invited) Probing the Intracellular Fate of Carbon Nanotube-Based Near-Infrared Sensors
Authors: Safaee Mohammad , Gravely Mitch , Restrepo David , Roxbury Daniel 
Published: February 2020

With the advent of nanotechnology in the diagnosis and treatment of cancer, many questions arise regarding whether novel nanomedicines, nanosensors, and nanoimaging agents are detrimental to living things. At a fundamental level, minute variations in size, shape, and charge can have overwhelming effects on the manner in which a live cell or animal will interact with a nanoparticle. A biomolecular corona, comprising proteins, carbohydrates, lipids, and small molecules, is known to form around nanoparticles and affects everything from the uptake of the nanoparticles into cells to the internal compartmentalization, processing, and eventual expulsion of the nanoparticles from the cells.
The intrinsic band-gap photoluminescence (fluorescence) of single-walled carbon nanotubes (SWCNTs) exhibits exceptional photostability, narrow bandwidth, near-infrared (NIR) tissue-penetrating emission, and microenvironmental sensitivity, enabling their usage in a variety of biomedical imaging and sensing applications. Of recent interest, a biocompatible formulation of carbon nanotubes has been used in the construction of a live-cell lipid accumulation sensor, a condition implicated in a variety of cancers. Additionally, fluorescent carbon nanotubes have been used to interrogate the permeability in multicellular tumor spheroid models. The biological identity of the nanotube sensor inside of the cell has not been thoroughly investigated. Here, by manipulating its composition, we examine the effects that the biomolecular corona has in determining the interactions between carbon nanotubes and live cells. In particular, we study the internalization, processing, toxicity, and long-term fate of the nanomaterial complexes in various types of mammalian cells. With a fundamental mechanistic understanding of the interactions between carbon nanotubes and live cells, we are able to engineer nanosensors with the most reduced toxicities, enhanced stabilities, and highest overall effectiveness.
(Invited) Room-Temperature Single Photon Emission from Micrometer-Long Air-Suspended Carbon Nanotubes
Authors: Ishii Akihiro , Uda Takushi , Kato Yuichiro K. 
Published: February 2020

Carbon nanotubes have a potential for becoming an ideal single-photon source as they have stable exciton states even at room temperature and their emission wavelengths cover the telecommunication bands. In recent years, single photon emission from carbon nanotubes has been achieved by creating localized states of excitons. In contrast to such an approach, here we utilize mobile excitons and show that single photons can be generated at room temperature in air-suspended carbon nanotubes with lengths of several microns [1]. We perform photoluminescence microscopy on as-grown air-suspended carbon nanotubes in order to determine their chirality and suspended length. Photon correlation measurements are performed on nanotube emission at room temperature using a Hanbury-Brown-Twiss setup with InGaAs single photon detectors. We observe antibunching with a clear excitation power dependence, where we obtain g
(2)(0) value less than 0.5 at low excitation powers, indicating single photon generation. We show such g
(2)(0) data for different chiralities and suspended lengths, and the effects of long exciton diffusion lengths and efficient exciton-exciton annihilation [2] on single photon generation processes are discussed.
Work supported by JSPS (KAKENHI JP16H05962) and MEXT (Photon Frontier Network Program, Nanotechnology Platform). T.U. is supported by ALPS and JSPS Research Fellowship.
[1] A. Ishii, T. Uda, Y. K. Kato, Phys. Rev. Applied, in press. Preprint available at arXiv:1707.05435 (2017).
[2] A. Ishii, M. Yoshida, Y. K. Kato, Phys. Rev. B 91, 125427 (2015).
Gas Atmosphere Effects over the Anode Compartment of a Tubular Direct Carbon Fuel Cell Module
Authors: Glenn Michael , Mathan Bobby , Islam Monirul , Beyad Yaser , Allen Jessica A , Donne Scott W 
Published: February 2020

The direct carbon fuel cell (DCFC) is an innovative low carbon technology option that has the potential to cause a paradigm shift in the way we generate electrical energy from coal resources. The technology is theoretically 100% efficient at extracting chemical energy of a carbon feedstock, with practically realizable cell efficiencies approaching 80% (cf. <40% in a state-of-the-art coal-fired power station). Since the reaction is the direct electrochemical generation of carbon dioxide, the flue gas has the potential to be pure, sequestration ready carbon dioxide with zero particulates with little to no flue gas treatment required.
This study examines the performance of a tubular 8 mol% yttria stabilised zirconia (YSZ) cell using a thermal coal char as the fuel, lanthanum strontium manganate (LSM) as the cathode material and a ternary alkali metal carbonate eutectic as the secondary electrolyte over the temperature range 700-900°C. The performance was compared when varying the gas atmosphere over the anode compartment between CO2 and N2 in separate experiments. It was found that the power density was two-fold as high under CO2 at 860°C. The reason for this is attributed to agitation provided to the fuel from reverse Bouduard gasification. This result implies that the anode performance is limited by mass transport of the carbon fuel to the silver current collector.