High surface area hybrids

The BET surface area of the hybrids was 31 m g i On the other hand, that of the hybrids subjected to heat-treatment at 350 C in air for 1 h was 339 m g"l (2) for diich the temperature increasing rate was 10 C min"l. Thus, the as-synthesized hybrids are referred to as "low-surface-area hybrids" and the hybrids after the heat-treatment as "high-surface-area hybrids" in this manuscript. 

In the DTA-TG curves of the low-surface-area hybrids shown in Pig. 1 (a), exothermic peaks accompanying weight loss appear in two temperature regions, 245-295 and 345-646 C. On the other hand, no peak appears in the range of 245-295 C in the DTA curve of the high-surface-area hybrids (data not shown). Ihis implies that the exothermic reaction at 245-295 C is related to the increase of the BBT surface area of the organic-silica hybrids. 

The C-to-Si atomic ratio of the low-surface-area hybrids (Anal. Pound C, 16.61 H, 4.36 Si, 39.92 %) is 0.97, whereas that of the high-surface-area hybrids (Anal. Pound C, 12.16 H, 3.33 Si, 40.81 %) is 0.70. This suggests that an organic component in the low-surface-area hybrids is removed upon the heat-treatment at 350 C, in other words, during the exothermic reaction at 245-295 C. 

Solid-state NMR spectra of the low- and high-surface-area hybrids are shown in Pig. 2 (a) and (b), respectively. An intensive signal at -2.2 ppm is assigned to the methyl group in units and that at 0.1 ppm to the methyl group in units in the hybrids (Hase-gawa, I. J. Sol-Gel Sci. Tecbnol., in press.). 

The most significant difference in the spectra lies in the intensity of the signal at 49.4 ppm, idiich is assigned to the methoxyl group in the CH3-0-Si= (7). The signal is intensive in the spectrum of the low-surface-area hybrids, while the signal is hardly seen in that of the high-surface-area hybrids. 

The CHs-O-Sis bond has been reported to give rise to a band at 2840 cm"l in IR spectra ( ). The band is visible in the PT-IR spectrum of the low-surface-area hybrids [Pig. 3 (a)], whereas the band hardly appears in that of the high-surface-area hybrids [Pig. 3 (b)]. 

Figure 3. PT-IR spectra of (a) the low-, (b) high-surface-area hybrids, (c) hybrids after the hydrolysis treatment, and (d) products formed on heating the low-surface-area hybrids at 800 C in air. The closed circle indicates a band corresponding to the CHa-O-Sis bond (2840 cm ). Assignments of intensive bands are as follows 3448 cm l, 0-H str. 2965 cm"l, C-H str. 1263 cm l, Si-CHa def. 1082 cm", Si-O-Si str. 850 and 804 cm", Si(-CHa)2...

Figure 4, The solid-state SP-MAS 29si NMR spectra of (a) the low-and (b) high-surface-area hybrids (obtained at a field of 39.7 MHz), and (c) the hybrids after the hydrolysis treatment (obtained at a field of 79.4 MHz).

For more efficient utilization of MOFs sorbents, several hybrid systems based on MOFs with other solid sorbents have been investigated in the literature. The objective of having hybrid materials is to utilize the synergism between the two sorbents and therefore ultimately improve the overall performance in C02 separation. Moreover, sorbents such as activated carbons, graphenes, and CNTs provide the added feature of high surface area and easily functionalized sites which contribute to the tuning of the final properties of the composite... 

Electrostatic interactions have recently been exploited for the synthesis of gra-phene-CNT hybrids. For example, poly(ethyleneimine) (PEI) coated graphene has been mixed with acid treated CNTs in a layer-by-layer method to form high surface area electrodes for supercapacitors [90]. Furthermore, Lu et al. prepared a supercapacitor electrode by mixing PDDA coated CNT-Mn02 hybrid with RGO [91]. 

The Langmuir-Blodgett method has been used to prepare hybrid films of an anionic Ru(ll) cyanide polypyridyl complex with LDHs [170]. An LDH film was formed on mica owing to the interaction between LDHs particles and the Ru(ll) cyanide polypyridyl complex that was pre-dispersed on the surface of mica. Water-in-oU emulsions composed of octane, water and sodium dodecyl sulfate (SDS) have been used to synthesize Mg/Al LDHs with carbonate as the interlayer anion [171] by constant pH or variable pH methods. A floccule or fiber-like LDH material that possesses similar chemical composition and properties to that synthesized using a conventional variable pH method was obtained. The resulting LDH shows high surface area and a narrow distribution of mesopores. 

Electrochemical capacitors have been studied for many years. The first patents date back to 1957, where a capacitor based on high surface area carbon was described by Becker. Later in 1969 first attempts to market such devices were undertaken by Standard Oil Company of Ohio (SOHIO). However, only in the 1990s did electrochemical capacitors become famous in the context of hybrid electric vehicles. The electrochemical capacitor (EC) was supposed to boost the battery or the fuel cell in the hybrid electric vehicle to provide the necessaiy power for acceleration, and additionally allow for recuperation of brake energy (Viswanathan, 2006). 

POSS, particularly the cubic (RSiOi,5)8 octamers, offer 4,4 cage structures akin to those found in Linde A and related zeohtes [201]. Zeohtes are the epitome of high surface area, controlled-porosity materials and are typically made by hydrothermal processes. In principle, the polymerization of selected organofunctional cubic silsesquioxanes could offer access to organic-inorganic hybrids with controlled surface area, porosity and fimctionality via nonaqueous methods. It follows that the main aspects of POSS-nanobuilding... 

---