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Because of concern about ion-pairing artifacts, the solvent dependence of the intervalence charge-transfer absorption energy for a prototypical mixed-valence system, (NH~)sR~"~-4,4'-bipyridine-Ru~~(NH~)s~+, has been reexamined in the limit of infinite dilution. New data are reported for 14 solvents. While one of these (hexamethylphosphoramide) yields anomalous energetics, the absorption energies for the remaining 13 solvents agree qualitatively with the predictions of the Marcus-Hush theory (Le., two-sphere dielectric continuum theory). On a quantitative basis, however, there is substantial disagreement with theory, at least when the charge-transfer distance is equated with the metal-to-metal separation distance (as conventionally done). Replacement of this distance with a much shorter distance inferred from by electronic Stark-effect spectroscopy (Oh et al. J. Am. Chem. SOC. 1990,112,8161) leads to a 3-fold decrease in the magnitude of calculated solvent reorganizational contributions to the overall intervalence energy (and therefore, very good agreement with experiment). Unfortunately, the use of such a short charge-transfer distance (d = 5.1 f 0.7 A) also leads to a violation of one of the boundary conditions for use of the two-sphere model. Reformulation of the problem in terms of a generalized dipole-inversion, dielectric cavity problem (Brunschwig et al. J. Phys. Chem. 1986, 90, 3657), however, leads to nearly perfect agreement between theory and experiment. Additional analysis shows that experiment now alsoagrees reasonably well with theory regarding the magnitudeof solvent-independent energy contributions. Finally, it is noted that downward revision in the estimated charge-transfer distance (from 11.3 to 5.1 A) leads to a substantial upward revision in the experimental (Le., oscillator-strength based) estimate of the electronic coupling element, Hir, for intervalence transfer. Further analysis, based on published data for longer bridges, suggests that charge-transfer distance revisions can also account (at least partially) for the seemingly weak dependence of Hir on distance in decaammineruthenium systems.

Graphene fiber-based supercapacitors (SCs) are rising as having the greatest potential for portable/wearable energy storage devices. However, their rate performance is not well pleasing, which greatly impedes their broad practical applications. Herein, three-dimensional porous carbon nanotube/reduced graphene oxide fibers were prepared by a nonsolvent-induced rapid phase separation method followed by hydrazine vapor reduction. Benefitting from their three-dimensional porous structure, large specific surface area, and high conductivity, the fabricated SC exhibits a high volume capacitance of 54.9 F cm–3 and high energy and power densities (4.9 mW h cm–3 and 15.5 W cm–3, respectively). Remarkably, the SC works well at a high scan rate of 50 V s–1 and shows a fast frequency response with a short time constant of 78 ms. Furthermore, the fiber-shaped SC also exhibits very stable electrochemical performances when it is subjected to mechanical bending and succeeding straightening process, indicating its great potential application in flexible electronic devices.

related operations, and destroy the operation of the whole equipment (system). Bao and his colleagues developed a novel self-healing and mechanical force-sensing flexible sensor using micro-structured elastomeric dielectrics, which served as a foundation to improve the stability and lifetime of flexible sensors. [8] Self-healing flexible materials can be divided into two categories, one is solvent-less or water-free after curing and high degree of polymerization of elastomers, such as polyamide, polyurethane, etc., the other is hydrogels, low degree of polymerization, structural cross-linking. In self-healing flexible elastomer sensors, the structure of elastomer is mostly linear structure or semi-cross-linked structure; the elastomer of cross-linked structure is poor flexibility and fragile due to its high degree of polymerization. The elasticity of semi-crosslinked structure has excellent resilience and great potential in the field of flexible flexural sensors. In the past two years, self-healing flexible hydrogels have attracted extensive attention due to their excellent stretchability and resilience, as well as outstanding performance in the preparation of sensors with high sensitivity and fast response. [9,10] Sensors with elastomers and hydrogels as flexible matrices face great difficulties in conductivity, which affects the sensitivity and stability of the sensors. Filling conductive materials is the most commonly method, in which organic conductive polymers (polyaniline, [11] polypyrrole [12]) are filled to construct conductive networks, and good interfacial compatibility results in uniform conductive polymer elastomers, but the inherent color fillers affect the transparency of flexible sensors, limiting their applications in the biomedical field. [13-17] Flexible materials filled with inorganic conductive particles (graphene, nano-silver wire) have high conductivity, but phase separation between filler and matrix usually reduces the tensile, toughness and fatigue resistance, and even affects the self-healing ability of flexible materials. Modified fillers are often required to improve affinity for flexible matrices and inhibit phase separation. However, many hydrogel matrices are intrinsically weak and cannot withstand cyclic loadings. [18] Although surface modified fillers can improve strength and toughness, it is difficult to compensate for the inherent weaknesses. For self-healing flexible elastomers, conductive flexible materials can still be endowed with conductivity by scraping or printing conductive particles on the Flexible pressure and strain sensors have great potential for applications in wearable and implantable devices, soft robots, and artificial skin. The introduction of self-healing performance has made a positive contribution to the lifetime and stability of flexible sensors. At present, many self-healing flexible sensors with high sensitivity have been developed to detect the signal of organism activity. The sensitivity, reliability, and stability of self-healing flexible sensors depend...