Micrometer scaled MoS2 hierarchical hollow cubic cages assembled by bilayers can be synthesized via a one-step self-assembly coupled with intermediate crystal templating process without any surfactant, in which the intermediate K2NaMoO3F3 crystal formed in-situ and then served as the self-sacrificed template based on the Kirkendall Effect; The MoS2 hierarchical hollow cubic cages were employed for electrochemical hydrogen storage with a high capacity of 375 mAh g(-1) due to the more active edges exposing on the upright-standing nanoplates.

As a kind of typical soft and wet material, hydrogel has been increasingly investigated as another way to develop flexible electronics. However, the traditional hydrogel with poor strain and strength performance cannot meet the requirements for stretchable electronics; fabricating a stretchable hydrogel with balanced tensile strength, toughness, and conductivity is still a big challenge. Herein, a new type of physically cross-linked hydrogel with poly(acrylamide-co-acrylic acid)-Fe 3+ and chitosan-SO 4 2− dual ionic networks via facile free radical polymerization and soaking processes is developed to fabricate excellent highperformance flexible sensors. The abundant Fe 3+ and SO 4 2− ions in the hydrogel can not only construct tough and strong dual ionic networks but also give the hydrogel high conductivity. Consequently, the optimal hydrogel possesses high tensile strength (∼5.1 MPa), large strain capacity (∼1225%), elasticity (∼1.13 MPa), high toughness (∼32.1 MJ/m 3 ), and high conductivity (3.04 S/m at f = 0.1M), as well as rapid self-recovery property. Furthermore, the hydrogel conductor has high stretching sensitivity with a gauge factor of 6.0 at strain of 700% and was able to detect conventional motions of the human body such as the motions of the knuckle, speaking, and swallowing, which indicates that our ionic conductive hydrogels can be used to fabricate excellent high-performance flexible sensors.

Three series of cobalt tetraarylporphyrins were synthesized and characterized by electrochemistry and spectroelectrochemistry. The investigated compounds have the general formula (TpYPP)Co, butano(TpYPP)Co, and benzo(TpYPP)Co, where TpYPP represents the dianion of the meso-substituted porphyrin, Y is a CH, H, or Cl substituent on the para position of the four phenyl rings, and butano and benzo are respectively the β- and β'-substituted groups on the four pyrrole rings of the compound. Each porphyrin undergoes one or two reductions depending upon the meso substituent and solvent utilized. Two irreversible reductions are observed for (TpYPP)Co and butano(TpYPP)Co in CHCl containing 0.1 M tetra-n-butylammonium perchlorate; the first leads to the formation of a highly reactive cobalt(I) porphyrin, which can then rapidly react with a solvent to give a CoCHCl as the product. Only one reversible reduction is seen for benzo(TpYPP)Co under the same solution conditions, and the one-electron-reduction product is assigned as a cobalt(II) porphyrin π-anion radical. Three oxidations can be observed for each examined compound in CHCl. The first oxidation is metal-centered for the (TpYPP)Co and benzo(TpYPP)Co derivatives, leading to generation of a cobalt(III) porphyrin with an intact π-ring system, but this redox process is ring-centered in the case of butano(TpYPP)Co and gives a Co π-cation radical product. Each porphyrin was also examined as a catalyst for oxygen reduction reactions (ORRs) when adsorbed on a graphite electrode in 1.0 M HClO. The number of electrons transferred (n) during ORRs is 2.0 for the butano(TpYPP)Co derivatives, consistent with only HO being produced as a product for the reaction with O. However, the reduction of O using the cobalt benzoporphyrins as catalysts gave n values between 2.6 and 3.1 under the same solution conditions, thus producing a mixture of HO and HO as the reduction product. This result indicates that the β and β' substituents have a significant effect on the catalytic properties of the cobalt porphyrins for ORRs in acid media.

Recent studies and device demonstrations indicate that horizontally aligned arrays of linearly configured single-walled carbon nanotubes (SWNTs) can serve as an effective thin film semiconductor material, suitable for scalable use in high-performance transistors. This paper presents the results of systematic investigations of the dependence of device properties on channel length, to reveal the role of channel and contact resistance in the operation. The results indicate that, for the range of channel lengths and SWNT diameters studied here, source and drain contacts of Pd yield transistors with effectively Ohmic contacts that exhibit negligible dependence of their resistances on gate voltage. For devices that use Au, modulation of the resistance of the contacts represents a significant contribution to the response. Extracted values of the mobilities of the semiconducting SWNTs and the contact resistances associated with metallic and semiconducting SWNTs are consistent with previous reports on single tube test structures.