tion. A drop of Nylon 6,6±isopropanol suspension was deposited on a carbon-coated TEM grid. The grid was shadowed with a thin layer of platinum. A JEOL (1200 EX II) TEM with an accelerating voltage of 120 kV was used and calibration of the SAED spacing was done using TlCl standards. A Digital Instrument Nanoscope IIIA was used for AFM experiments. A drop of Nylon 6,6 crystal suspension was deposited on a carbon-coated glass slide. The force used by the cantilever was light enough to limit damage to the sample, yet obtain accurate surface features. The scanning rate was 1±3 Hz for the low magnification images (512 512 pixels per image). Arrays of close-packed, equal-sized microspheres have been used as templates for the micro-and nano-fabrication of optical materials. Colloidal suspensions of such monodisperse spheres can be especially useful in making optical materials because they can self-organize into ordered, hexagonally packed crystalline lattices in two or three dimensions. Received[1] These opaline lattices can exhibit optical insulating behavior (i.e., they can have a photonic bandgap (PBG)), similar to semiconductors in electronic devices, and are called photonic crystals. The optical insulating behavior of photonic crystals arises from the cooperative scattering of light from the ordered array of particles.[2] However, these opaline structures do not have a full PBG but only a few narrow stop bands. It is known that inverse opaline structures exhibit wider stop bandgaps, and can possess a full PBG when the refractive index contrast exceeds about 2.8. The inverse opaline structures are formed by infiltrating dielectric material into the interstices between the colloidal spheres and then dissolving the spheres away. [3] This produces an ordered foam of spherical cavities. The stop bands of opals or inverse opals with a face-centered cubic arrangement can be exploited to modify the spontaneous emission of organic dyes and semiconductor nanocrystals embedded in the voids of the colloidal crystals.[4]One of the important issues in the design of photonic crystals is the control of their uniformity in size and shape. This is required for the development of photonic devices, including waveguides and optical components, such as microlenses and beam splitters.[5±7] For other applications, photonic crystals in the form of colloidal clusters could be especially valuable, for example, as light scatterers, light diffusers, and pigments for electronic paper and electronic displays.[8±10] The practical use of these materials, however, requires the production of large quantities of monodisperse colloidal clusters. Here, we report a simple, single-step synthetic route for the generation of uniform colloidal aggregates and their inverse structures by electrospraying an aqueous colloidal suspension. Hereafter, both our opaline balls and their inverse structures COMMUNICATIONS

Eutectic mixtures of alkali nitrates are known to increase the sorption capacity and kinetics of MgO-based sorbents. Underlying principles and mechanisms for CO capture on such sorbents have already been established; however, real-time observation of the system was not yet accomplished. In this work, we present the direct-observation of the CO capture phenomenon on a KNO-LiNO eutectic mixture (EM)-promoted MgO sample, denoted as KLM, via in situ transmission electron microscopy (in situ TEM). Results revealed that the pseudoliquid EM undergoes structural rearrangement as MgCO evolves from the surface of MgO, resulting in surface roughening and evolution of cloudy structures that stay finely distributed after regeneration. From this, we propose a nucleation and structural rearrangement scheme for MgCO and EM, which involves the rearrangement of bulk EM to evenly distributed EM clusters due to MgCO saturation as adsorption proceeds. We also conducted studies on the interface between EM over solid MgO and MgCO formed during sorption, which further clarifies the interaction between MgO and EM. This study provides better insight into the sorption and regeneration mechanism, as well as the structural rearrangements involved in EM-promoted sorbents by basing not only on intrinsic evolutions but also on real-time observation of the system as a whole.

Achieving high energy storage performance and fast rate capability at the same time is one of the most critical challenges in battery technology. Here, a high‐performance textile cathode with notable specific/areal capacities and high rate capability through an interfacial interaction‐mediated assembly that can directly bridge all interfaces existing between textile and conductive materials and between conductive and active materials, minimizing unnecessary insulating organics is reported. First, amine (NH2)‐ and carboxylic acid (COOH)‐functionalized multiwalled carbon nanotubes (MWNTs) are alternately layer‐by‐layer (LbL)‐assembled onto cellulose textiles for the preparation of conductive textiles using hydrogen bonding interactions. Dioleamide‐stabilized LiFePO4 nanoparticles (DA‐LFP NPs) with high crystallinity and high dispersion stability in organic media are consecutively LbL‐assembled with MWNT‐NH2 onto conductive textiles through ligand replacement between native DA ligands bound to the surface of the LFP NPs and NH2 groups of MWNTs. In this case, 35 nm sized LFP NPs are densely and uniformly adsorbed onto all regions of the textile, and additionally, their areal capacities are increased according to the deposition number without a significant loss of charge transfer kinetics. The formed textile cathodes exhibit remarkable specific/areal capacities (196 mAh g−1/8.3 mAh cm−2 at 0.1 C) and high rate capability with highly flexible mechanical properties.

Electrical conductivity, mechanical flexibility, and large electroactive surface areas are the most important factors in determining the performance of various flexible electrodes in energy storage devices. Herein, a layer‐by‐layer (LbL) assembly‐induced metal electrodeposition approach is introduced to prepare a variety of highly porous 3D‐current collectors with high flexibility, metallic conductivity, and large surface area. In this study, a few metal nanoparticle (NP) layers are LbL‐assembled onto insulating paper for the preparation of conductive paper. Subsequent Ni electroplating of the metal NP‐coated substrates reduces the sheet resistance from ≈103 to <0.1 Ω sq−1 while maintaining the porous structure of the pristine paper. Particularly, this approach is completely compatible with commercial electroplating processes, and thus can be directly extended to electroplating applications using a variety of other metals in addition to Ni. After depositing high‐energy MnO NPs onto Ni‐electroplated papers, the areal capacitance increases from 68 to 811 mF cm−2 as the mass loading of MnO NPs increases from 0.16 to 4.31 mg cm−2. When metal NPs are periodically LbL‐assembled with the MnO NPs, the areal capacitance increases to 1710 mF cm−2.

No abstract

No abstract

No abstract

One of the most difficult challenges related to pseudocapacitive nanoparticle (PC NP)‐based energy storage electrodes with theoretically high capacity is to overcome the sluggish charge‐transfer kinetics that result from the poorly conductive PC NPs and bulky/insulating organics (i.e., organic ligands and/or polymeric binders) within the electrodes. Herein, it is reported that physical/chemical functionalities of organic ligands and their molecular‐scale coating onto NPs have considerable effects on the rate capability and capacity of oxide NP‐based pseudocapacitor electrodes. For this study, pseudocapacitive iron oxide (Fe3O4) NPs are layer‐by‐layer (LbL)‐assembled with conductive indium tin oxide (ITO) NPs using various types of organic ligands (or linkers). In particular, hydrazine ligands, which have extremely small molecular size and strong chemical reducing properties, can effectively remove bulky organic ligands from the NP surface, and thus reduce the separation distance between neighboring NPs. Simultaneously, the hydrazine ligands significantly increase the number of oxygen vacancies on Fe3O4 and ITO NPs during LbL deposition, which markedly enhances the rate capability and capacitance of the electrodes compared to other organic ligands with bulky size and/or without reducing properties. This approach can provide a fundamental basis for developing and designing various high‐performance electrochemical electrodes based on metal oxide NPs.