Sung You Hong

Charge carriers in rechargeable batteries: Na ions vs. Li ions

We discuss the similarities and dissimilarities of sodium- and lithium-ion batteries in terms of negative and positive electrodes. Compared to the comprehensive body of work on lithium-ion batteries, research on sodium-ion batteries is still at the germination stage. Since both sodium and lithium are alkali metals, they share similar chemical properties including ionicity, electronegativity and electrochemical reactivity. They accordingly have comparable synthetic protocols and electrochemical performances, which indicates that sodium-ion batteries can be successfully developed based on previously applied approaches or methods in the lithium counterpart. The electrode materials in Li-ion batteries provide the best library for research on Na-ion batteries because many Na-ion insertion hosts have their roots in Li-ion insertion hosts. However, the larger size and different bonding characteristics of sodium ions influence the thermodynamic and/or kinetic properties of sodium-ion batteries, which leads to unexpected behaviour in electrochemical performance and reaction mechanism, compared to lithium-ion batteries. This perspective provides a comparative overview of the major developments in the area of positive and negative electrode materials in both Li-ion and Na-ion batteries in the past decade. Highlighted are concepts in solid state chemistry and electrochemistry that have provided new opportunities for tailored design that can be extended to many different electrode materials for sodium-ion batteries.

Sodium Terephthalate as an Organic Anode Material for Sodium Ion Batteries

Disodium terephthalate and its various derivatives are synthesized via simple acid-base chemistry for anode materials in Na ion batteries. They show excellent electrochemical performance, including little capacity fading over 90 cycles, ideal redox potential, and excellent rate performance, making them promising candidates for Na ion batteries.

Filled and glycosylated carbon nanotubes for in vivo radioemitter localization and imaging

Functionalization of nanomaterials for precise biomedical function is an emerging trend in nanotechnology. Carbon nanotubes are attractive as multifunctional carrier systems because payload can be encapsulated in internal space whilst outer surfaces can be chemically modified. Yet, despite potential as drug delivery systems and radiotracers, such filled-and-functionalized carbon nanotubes have not been previously investigated in vivo. Here we report covalent functionalization of radionuclide-filled single-walled carbon nanotubes and their use as radioprobes. Metal halides, including Na(125)I, were sealed inside single-walled carbon nanotubes to create high-density radioemitting crystals and then surfaces of these filled-sealed nanotubes were covalently modified with biantennary carbohydrates, improving dispersibility and biocompatibility. Intravenous administration of Na(125)I-filled glyco-single-walled carbon nanotubes in mice was tracked in vivo using single-photon emission computed tomography. Specific tissue accumulation (here lung) coupled with high in vivo stability prevented leakage of radionuclide to high-affinity organs (thyroid/stomach) or excretion, and resulted in ultrasensitive imaging and delivery of unprecedented radiodose density. Nanoencapsulation of iodide within single-walled carbon nanotubes enabled its biodistribution to be completely redirected from tissue with innate affinity (thyroid) to lung. Surface functionalization of (125)I-filled single-walled carbon nanotubes offers versatility towards modulation of biodistribution of these radioemitting crystals in a manner determined by the capsule that delivers them. We envisage that organ-specific therapeutics and diagnostics can be developed on the basis of the nanocapsule model described here.

Highly Transparent and Stretchable Field‐Effect Transistor Sensors Using Graphene–Nanowire Hybrid Nanostructures

Transparent and stretchable electronics with remarkable bendability, conformability, and lightness are the key attributes for sensing or wearable devices. Transparent and stretchable field-effect transistor sensors using graphene-metal nanowire hybrid nanostructures have high mobility (≈3000 cm(2) V(-1) s(-1) ) with low contact resistance, and they are transferrable onto a variety of substrates. The integration of these sensors for RLC circuits enables wireless monitoring.

Design, synthesis and biological evaluation of carbohydrate-functionalized cyclodextrins and liposomes for hepatocyte-specific targeting†

Targeting glycan-binding receptors is an attractive strategy for cell-specific drug and gene delivery. The C-type lectin asialoglycoprotein receptor (ASGPR) is particularly suitable for liver-specific delivery due to its exclusive expression by parenchymal hepatocytes. In this study, we designed and developed an efficient synthesis of carbohydrate-functionalized β-cyclodextrins (βCDs) and liposomes for hepatocyte-specific delivery. For targeting of ASGPR, rhodamine B-loaded βCDs were functionalized with glycodendrimers. Liposomes were equipped with synthetic glycolipids containing a terminal D-GalNAc residue to mediate binding to ASGPR. Uptake studies in the human hepatocellular carcinoma cell line HepG2 demonstrated that βCDs and liposomes displaying terminal D-Gal/D-GalNAc residues were preferentially endocytosed. In contrast, uptake of βCDs and liposomes with terminal d-Man or D-GlcNAc residues was markedly reduced. The d-Gal/d-GalNAc-functionalized βCDs and liposomes presented here enable hepatocyte-specific targeting. Gal-functionalized βCDs are efficient molecular carriers to deliver doxorubicin in vitro into hepatocytes and induce apoptosis.

The Role of Palladium Dynamics in the Surface Catalysis of Coupling Reactions

Ever since its discovery, the carbon–carbon cross-coupling reaction has contributed greatly to increasing the chemical complexity of molecules, which is crucial for organic synthesis and pharmaceutical drug development. Surface-catalyzing carbon–carbon bond formation on supported Pd nanoparticles (PdNPs) can decrease product contamination and aid the development of “greener” routes in organic synthesis. On the nanoscale, unlike in the bulk phase, PdNPs exhibit a large specific surface area and have abundant low coordination sites that enable increased catalytic activity. However, the catalytic reaction mechanisms on supported PdNPs surfaces remain a controversial topic of discussion. Some reports suggest that surface sites on PdNPs may play a crucial role in catalyzing coupling reactions, while others propose that the Pd species leached from support into solution govern the reaction pathways. Surface analysis of supported PdNPs used during crosscoupling reactions with atomic precision is difficult. Recent work suggests that PdNPs smaller than 1 nm are commonly missed during most microscopic studies. In addition, signal collection on highly dispersed particles after cross-coupling reactions is challenging owing to geometric and electric interference with the surface of bulk support. Herein, we set out to investigate the catalytic performance of PdNPs, in the Suzuki–Miyaura reaction, supported on materials with various levels of functionalization. The Pd dynamics were investigated in terms of changes to the surface of the PdNPs and to the support and correlated with catalytic results. Unlike previous reports applying active carbon, silica, alumina, or zeolites in the heterogeneous catalysis of coupling reactions, the current work exploits functionalized carbon nanotubes (CNTs) as a support. To study the influence of the chemical properties of the supporting materials on the Pd dynamics, CNTs were functionalized to different degrees before being loaded with PdNPs for use in coupling reactions. After synthesis the CNTs underwent annealing treatments at 700 8C and 1500 8C to improve the graphitization. For functionalization the CNTs were added to vigorously stirred concentrated nitric acid at 120 8C. CNTs annealed at 700 8C have more defects than CNTs annealed at 1500 8C, HNO3 treatment introduced a high functionalization (HCNTs) on defective CNTs and a low functionalization (LCNTs) on graphitized CNTs. The functionalities act as sites for anchoring metal cations during impregnation. Vacancies and cavities in the CNTs may also play entrap PdNP precursors. The STEM image in Figure 1a shows the dispersion of PdNPs (2% wt palladium) on H-CNTs (Pd/H-CNTs) with a size distribution of (1.8 0.2) nm. Figure 1b shows a poor dispersion of PdNPs (2% wt palladium) on L-CNTs (Pd/LCNTs) with a larger size distribution of (14.5 0.2) nm. Figure 1c shows plots of conversion versus reaction time for the Suzuki–Miyaura reaction of iodobenzene with phenylboronic acid in the presence of these PdNP/CNT catalysts. Quantitative conversion was obtained within one hour when Pd/H-CNTs was used, whereas reactions with Pd/L-CNTs required 8 h to reach quantitative conversion. The turnover frequency (TOF) at completion of the reaction is 990 h 1 for Pd/H-CNTs and 124 h 1 for Pd/L-CNTs. Figure 1d shows the Suzuki–Miyaura reaction solution of Pd/H-CNTs after one hour reaction time. This black solution could be left to stand for 10 min and no precipitate was observed. Filtration using normal filter papers collected all the Pd/H-CNTs and result in a clear filtrate (Figure 1e). The reaction solution of Pd/LCNTs after one hour reaction time, precipitated completely on being allowed to stand for 10 min (Figure 1 f). The significant differences in reactivity prompted a detailed analysis of the catalysts by electron microscopy. Reactions were stopped at 1 hour for Pd/H-CNTs and Pd/LCNTs. Although the majority H-CNTs were intact (Supporting Information, Figure S1), some showed damage after catalyzing the coupling reaction. The morphology changes to the Pd/H-CNTs are shown in Figure 2a,b. The STEM image in Figure 2a shows the dispersion of PdNPs on a structurally damaged H-CNT. Although some PdNPs have a larger size, PdNPs with a diameter of 1–2 nm are still visible. A detailed view of the damaged H-CNTs after reaction, was obtained by TEM (Figure 2b). “Tracks” from the movement [*] Dr. L. Shao, Dr. B. Zhang, Dr. W. Zhang, Prof. Dr. R. Schlcgl, Dr. D. S. Su Fritz Haber Institute of the Max Planck Society Faradayweg 4–6, 14195 Berlin (Germany) E-mail: dangsheng@fhi-berlin.mpg.de Homepage: www.fhi-berlin.mpg.de

Removal of amorphous carbon for the efficient sidewall functionalisation of single-walled carbon nanotubes

The sidewall functionalisation of carbon nanotubes using the standard nitric acid treatment can be greatly enhanced by first removing the amorphous carbon present in the sample.

Organic-Catholyte-Containing Flexible Rechargeable Lithium Batteries

Organic-catholyte-containing flexible rechargeable lithium batteries are developed using fused cyclic quinone derivatives. The structural dependence of the quinone isomers in the liquid catholyte is studied using a combined experimental and theoretical approach. Stable electrochemical performance even under severe bending/stretching deformations is successfully demonstrated by prototype batteries containing liquid catholytes.

Core-shell PbI2@WS2 inorganic nanotubes from capillary wetting.

Multiwall WS(2) nanotube templates were used as hosts to prepare core-shell PbI(2)@WS(2) nanotubes by a capillary-wetting method. Conformal growth of PbI(2) layers on the inner wall of the relatively wide WS(2) nanotubes (i.d. ca. 10 nm) leads to nanotubular structures which were not previously observed in narrow carbon nanotube templates. Image simulation after structural modeling (see picture) showed good agreement with the experimental HRTEM image.

Ferritin protein cage nanoparticles as versatile antigen delivery nanoplatforms for dendritic cell (DC)-based vaccine development

UNLABELLED We utilized ferritin protein cage nanoparticles (FPCN) as antigen delivery nanoplatforms for DC-based vaccine development and investigated DC-mediated antigen-specific immune responses. Antigenic peptides, OT-1 (SIINFEKL) or OT-2 (ISQAVHAAHAEINEAGR) which are derived from ovalbumin, were genetically introduced either onto the exterior surface or into the interior cavity of FPCN. FPCN carrying antigenic peptides (OT-1-FPCN and OT-2-FPCN) were effectively delivered to DCs and processed within endosomes. Delivered antigenic peptides, OT-1 or OT-2, to DCs successfully induced antigen-specific CD8(+) or CD4(+) T cell proliferations both in vitro and in vivo. Naïve mice immunized with OT-1-FPCN efficiently differentiated OT-1 specific CD8(+) T cells into functional effector cytotoxic T cells resulting in selective killing of antigen-specific target cells. Effective differentiation of proliferated OT-2 specific CD4(+) T cells into functional CD4(+) Th1 and Th2 cells was confirmed with the productions of IFN-γ/IL-2 and IL-10/IL-13 cytokines, respectively. FROM THE CLINICAL EDITOR In this study, the authors utilized ferritin protein cage nanoparticles as antigen delivery nanoplatforms for dendritic cell-based vaccine development and investigated DC-mediated antigen-specific immune responses using strong model antigens derived from ovalbumin, suggesting potential future clinical applicability of this or similar techniques.