[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Titanium Dioxide Nanomaterials: Synthesis, Properties, Modifications, and Applications

Polydopamine and Its Derivative Materials: Synthesis and Promising Applications in Energy, Environmental, and Biomedical Fields

The recent advances in electrocatalysis for oxygen reduction reaction (ORR) for proton exchange membrane fuel cells (PEMFCs) are thoroughly reviewed. This comprehensive Review focuses on the low- and non-platinum electrocatalysts including advanced platinum alloys, core–shell structures, palladium-based catalysts, metal oxides and chalcogenides, carbon-based non-noble metal catalysts, and metal-free catalysts. The recent development of ORR electrocatalysts with novel structures and compositions is highlighted. The understandings of the correlation between the activity and the shape, size, composition, and synthesis method are summarized. For the carbon-based materials, their performance and stability in fuel cells and comparisons with those of platinum are documented. The research directions as well as perspectives on the further development of more active and less expensive electrocatalysts are provided.

http://repository.ust.hk/ir/bitstream/1783.1-77094/1/acs.chemrev.5b00462_withlink.pdf

Recent Advances in Electrocatalysts for Oxygen Reduction Reaction

TiO(2) is one of the most studied compounds in materials science. Owing to some outstanding properties it is used for instance in photocatalysis, dye-sensitized solar cells, and biomedical devices. In 1999, first reports showed the feasibility to grow highly ordered arrays of TiO(2) nanotubes by a simple but optimized electrochemical anodization of a titanium metal sheet. This finding stimulated intense research activities that focused on growth, modification, properties, and applications of these one-dimensional nanostructures. This review attempts to cover all these aspects, including underlying principles and key functional features of TiO(2), in a comprehensive way and also indicates potential future directions of the field.

TiO2 nanotubes: synthesis and applications.

Monodispersed manganese oxide (Mn1−xCox)3O4 (0 ≤ x ≤ 0.5) nanoparticles, less than 10 nm size, are respectively synthesized via a facile thermolysis method at a rather low temperature, ranging from 90 to 100 °C, without any inertia gas for protection. The influences of the Co dopant content on the critical reaction temperature required for the nanoparticle formation, electronic band structures, magnetic properties, and the microwave absorption capability of (Mn1−xCox)3O4 are comprehensively investigated by means of both experimental and theoretical approaches including powder X-ray diffraction (XRD), electron energy loss spectroscopy (EELS), super conductivity quantum interference device (SQUID) examination, and first-principle simulations. Co is successfully doped into the Mn atomic sites of the (Mn1−xCox)3O4 lattice, which is further confirmed by EELS data acquired from one individual nanoparticle. Therefore, continuous solid solutions of well-crystallized (Mn1−xCox)3O4 products are achieved without any impurity phase or phase separation. With increases in the Co dopant concentration x from 0 to 0.5, the lattice parameters change systemically, where the overall saturation magnetization at 30 K increases due to the more intense coupling of the 3d electrons between Mn and Co, as revealed by simulations. The microwave absorption properties of the (Mn1−xCox)3O4 nanoparticles are examined between 2 and 18 GHz. The maximum absorption peak −11.0 dB of the x = 0 sample is enhanced to −11.5 dB for x = 0.2, −12.7 dB for x = 0.25, −15.6 dB for x = 0.33, and −24.0 dB for x = 0.5 respectively, suggesting the Co doping effects. Our results might provide novel insights into the understanding of the influences of metallic ion doping on the electromagnetic properties of metallic oxide nanomaterials.

Microwave absorption enhancement, magnetic coupling and ab initio electronic structure of monodispersed (Mn1−xCox)3O4 nanoparticles

Hierarchical Magnetic-Dielectric Synergistic Co/Coo/Rgo Microspheres with Excellent Microwave Absorption Performance Covering the Whole X Band

Drawing advanced electromagnetic functional composites with ultra-low filler loading

Recently, transition metal oxides have attracted great attention as anode materials for lithium-ion batteries due to their high theoretical capacities. However, their poor electrical conductivity, unstable cycling performance and unclear additional capacity are still great challenges. Herein, CoxMnyNizO (x : y : z = 8 : 0.92 : 0.71) nanosheets corresponding to the cubic CoO phase directly formed on a Cu foil (CMN-CH) were fabricated and directly tested as binder-free anode electrodes for lithium-ion batteries. The unique preparation of the electrode without a binder effectively accelerated the transfer of Li+ ions and electrons. Additionally, much more active sites were exposed to the electrolyte in the absence of additives (binder and conductive carbon). Metal vacancies and oxygen vacancies could be clearly observed in the crystal lattices, which were induced by doping Mn and Ni atoms in the CoO crystal lattices. The prepared CMN-CH electrode demonstrated superior capacities of 1501 mA h g−1 at 5 A g−1 after 1500 cycles and 823 mA h g−1 at 10 A g−1 after 1500 cycles, which are far beyond the theoretical capacity of CoO (716 mA h g−1) and surpass that of most CoO-based composites with carbon materials reported in the literature. The reversible conversion between Co2+ and Co3+ during the cycling process contributed greatly to the reversible capacity. Based on the obtained excellent electrochemical capacities, the prepared CMN-CH has great potential to be used as an anode electrode for lithium-ion batteries.

Superior-capacity binder-free anode electrode for lithium-ion batteries: CoxMnyNizO nanosheets with metal/oxygen vacancies directly formed on Cu foil

The combination of high-capacity and long-term cycling stability is an important factor for practical application of anode materials for lithium-ion batteries. Herein, Nix Mny Coz O nanowire (x + y + z = 1)/carbon nanotube (CNT) composite microspheres with a 3D interconnected conductive network structure (3DICN-NCS) are prepared via a spray-drying method. The 3D interconnected conductive network structure can facilitate the penetration of electrolyte into the microspheres and provide excellent connectivity for rapid Li+ ion/electron transfer in the microspheres, thus greatly reducing the concentration polarization in the electrode. Additionally, the empty spaces among the nanowires in the network accommodate microsphere volume expansion associated with Li+ intercalation during the cycling process, which improves the cycling stability of the electrode. The CNTs distribute uniformly in the microspheres, which act as conductive frameworks to greatly improve the electrical conductivity of the microspheres. As expected, the prepared 3DICN-NCS demonstrates excellent electrochemical performance, showing a high capacity of 1277 mAh g-1 at 1 A g-1 after 2000 cycles and 790 mAh g-1 at 5 A g-1 after 1000 cycles. This work demonstrates a universal method to construct a 3D interconnected conductive network structure for anode materials.

Ni x Mn y Co z O Nanowire/CNT Composite Microspheres with 3D Interconnected Conductive Network Structure via Spray-Drying Method: A High-Capacity and Long-Cycle-Life Anode Material for Lithium-Ion Batteries.

Renchao Che

Papers

Microwave absorption enhancement, magnetic coupling and ab initio electronic structure of monodispersed (Mn1−xCox)3O4 nanoparticles

Hierarchical Magnetic-Dielectric Synergistic Co/Coo/Rgo Microspheres with Excellent Microwave Absorption Performance Covering the Whole X Band

Drawing advanced electromagnetic functional composites with ultra-low filler loading

Superior-capacity binder-free anode electrode for lithium-ion batteries: CoxMnyNizO nanosheets with metal/oxygen vacancies directly formed on Cu foil

Ni x Mn y Co z O Nanowire/CNT Composite Microspheres with 3D Interconnected Conductive Network Structure via Spray-Drying Method: A High-Capacity and Long-Cycle-Life Anode Material for Lithium-Ion Batteries.