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A variety of shape-controlled TiO2 nanoparticles, such as spheres, short ellipsoidal rods with a low aspect ratio (low AR), and long ellipsoidal rods with a high aspect ratio (high AR), were synthesized by a gel−sol method. X-ray diffractometer and ultraviolet diffuse reflectance spectroscopy analyses revealed that the synthesized TiO2 nanoparticles have the same anatase structure with a band-gap energy (E g) of 3.2 eV regardless of nanoparticle shape. Electrochemical impedance spectroscopy (EIS) results showed that the increasing aspect ratio of TiO2 nanoparticles was accompanied by increases in the charge-transfer rate between nanoparticle surfaces and electrolyte, the space charge capacitance on the surface of TiO2 nanoparticles, and electrochemical double-layer capacitance at the interfacial region of the electrolyte. The amount of electron donors in the nanoparticles increased with increasing aspect ratio of nanoparticles, which is in good agreement with EIS results. Use of high-AR ellipsoidal TiO2 nanoparticles as photocatalysts resulted in enhanced current density and, consequently, an increase in the photocatalytic decomposition rate of formic acid.

Despite the 3–5 fold higher energy density than the conventional Li‐ion cells at a lower cost, commercialization of Li–S batteries is hindered by the insulating nature of sulfur and the dissolution of intermediate polysulfides (Li2S X , 4 < X ≤ 8) into the electrolyte. The authors demonstrate here multichannel carbon nanofibers that are composed of parallel mesoporous channels connected with micropores as sulfur containment. In addition, hydroxyl functional groups are formed on the carbon surface through a chemical activation to enhance the interaction between sulfur and carbon. In the sulfur embedded composite, the mesoporous multichannel enhances the active material utilization and sulfur loading, while the micropores act as a reaction chamber for sulfur component and trap site for polysulfide with the assistance of the functional groups. This sulfur–carbon composite electrode with 2.2 mg cm−2 sulfur displays excellent performance with high rate capability (initial capacity of 1351 mA h g−1 at C/5 rate and 847 mA h g−1 at 5C rate), maintaining 920 mA h g−1 even after 300 cycles (a decay of 0.07% per cycle). Furthermore, a stable reversible capacity of as high as ≈1100 mA h g−1 is realized with a higher sulfur loading of 4.6 mg cm−2.

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Recent advances in micro electro-mechanical systems and VLSI lithography have enabled the miniaturization of sensors and controllers. Such minitiarization facilitates the deployment of large-scale wireless sensor networks (WSNs). However, the considerable cost of deploying and maintaining large-scale WSNs for experimental purposes makes simulation useful in developing dependable and portable WSN applications. SENS is a customizable sensor network simulator for WSN applications, consisting of interchangeable and extensible components for applications, network communication, and the physical environment. Multiple component implementations in SENSoffer varying degrees of realism. Users can assemble application-specific environments; such environments are modeled in SENS by their different signal propagation characteristics. The same source code that is executed on simulated sensor nodes in SENS may also be deployed on actual sensor nodes; this enables application portability. Furthermore, SENS provides diagnostic facilities such as power utilization analysis for development of dependable applications. We validate and demonstrate usability of these capabilities through analyzing two simple WSN services.

Due to rapid advances in technology which have contributed to the development of portable equipment, highly sensitive and selective sensor technology is in demand. In particular, many approaches to the modification of wireless sensor systems have been studied. Wireless systems have many advantages, including unobtrusive installation, high nodal densities, low cost, and potential commercial applications. In this study, we fabricated radio frequency identification (RFID)-based wireless sensor systems using carboxyl group functionalized polypyrrole (C-PPy) nanoparticles (NPs). The C-PPy NPs were synthesized via chemical oxidation copolymerization, and then their electrical and chemical properties were characterized by a variety of methods. The sensor system was composed of an RFID reader antenna and a sensor tag made from a commercially available ultrahigh frequency RFID tag coated with C-PPy NPs. The C-PPy NPs were covalently bonded to the tag to form a passive sensor. This type of sensor can be produced at a very low cost and exhibits ultrahigh sensitivity to ammonia, detecting concentrations as low as 0.1 ppm. These sensors operated wirelessly and maintained their sensing performance as they were deformed by bending and twisting. Due to their flexibility, these sensors may be used in wearable technologies for sensing gases.