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The effect of 1-hexanol on the phase behavior of aqueous solutions of sodium dodecyl sulfate (SDS) and cetyl trimethyl ammonium bromide (CTAB) has been systematically studied. The phase ranges of vesicle and liquid crystal (LC) can be greatly extended with the addition of 1-hexanol. These specific structures distributed symmetrically on the two sides of the SDS/CTAB equimolar line in the pseudo ternary phase diagram. The aqueous two phase system (ATPS) contained vesicles that would transform into lamellar LC with the change of ratio of SDS/CTAB. The phase behaviors of SDS/CTAB system with addition of different alcohols (C5OH-C8OH) showed similar trends in structural transition except for phase span, demonstrating that the obstruction of electrostatic interaction between surfactant polar heads was affected by the insertion depth of the added alcohols. [ABSTRACT FROM AUTHOR]

A Co-metal-organic-framework (MOF) crystal has been hydrothermally synthesized. Then the corresponding Co/nitrogen-doped porous carbon (Co/NPC) composite is fabricated by direct pyrolyzation of MOF without any precursor additive. The results reveal that the MOF-derived Co/NPC exhibits a porous structure with a surface area of 412 m2 g-1 and a narrow pore size distribution (from 1.8 to 4.9 nm). The doped N mainly occurs in pyridine N and graphitic N types with total content as 4.11 at.%, which is originated from the N-based ligands in MOF. As an efficient oxygen reduction reaction (ORR) catalyst, Co/ NPC shows a more positive onset potential (0.91 V vs. RHE) with a diffusionlimited current density of 5.46 mA cm-2 at 0.3 V (vs. RHE). The rotating disk electrode and rotating ring-disk electrode results suggest that the Co/NPC catalyst experiences a nearly 4e pathway with a stronger methanol tolerance and better durability than commercial Pt/C catalyst in 0.1 M KOH. The excellent ORR catalytic activity of Co/NPC can be attributed to the N-doped porous carbon structure with incorporated metallic Co active species. This work affords a new strategy for preparation of non-noble metal ORR catalysts employing MOF as a precursor. [ABSTRACT FROM AUTHOR]

The effect of additives on the phase behavior of aqueous solutions of sodium dodecyl sulfate (SDS) and cetyl trimethyl ammonium bromide (CTAB) has been studied in detail for extended applications. The results showed that both the widths of an anionic two-phase aqueous system (ATPSa) region with SDS in excess and a aqueous cationic two-phase system (ATPSc) region with CTAB in excess are very narrow, less than 1% in absence of any additives. However, phase regions of ATPS move toward the corresponding isotropic single phase regions and become wider in the presence of inorganic additives such as NaBr in the aqueous surfactant solutions. This is because the addition of inorganic salt increases the concentration of inorganic counter-ions and therefore the electrostatic interactions between counter-ions and surfactant aggregates. Meanwhile, the organic salts, sodium salicylate and tetrabutylammonium bromide, have been found to have a greater capacity to expand the range of ATPS because the electrostatic interactions between organic ions and aggregates were adjustable through the deformation of the electron cloud of organic ions. Organic additives with different properties can effectively extend the range of either ATPSc or ATPSa. Wherein, sodium salicylate can expand ATPSc efficiently and tetrabutylammonium bromide can expand ATPSa significantly. [ABSTRACT FROM AUTHOR]