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Vapor spontaneously diffuses from areas of high concentration to areas of low concentration as a consequence of the Second Law of Thermodynamics and the hunt for maximum entropy. The distribution of substances with lower saturated vapor pressures on a surface can create this concentration slope in the space. However, most substances, except ice, cannot maintain this slope because humidity sinking causes their saturated vapor pressure to drop. Moreover, the location of ice growth is difficult to control. In this paper, a pattern of CaCl2 was made on the micronano hierarchically aluminum substrate. When the temperature drops below zero, the vapor pressure at the position where CaCl2 is located is low relative to that of water as a way to achieve a continuous phase transition from solid CaCl2 to brine to ice. Thus, vapor nearby continuously diffuses to and deposits at the site, resulting in a lasting dry region around without water condensation. The frost growing on the pattern is also fluffy and can be easily removed by gravity and/or wind. This work has promising applications in areas where it is extremely difficult to use active deicing methods. [ABSTRACT FROM AUTHOR]

Three novel amphiphilic dicephalic (double-headed) surfactants containing oligo(ethylene-oxide)methyl-ether and a sugar moiety TGA-m(m= 1, 2, and 3) that incorporate a tetrasiloxane at the terminus of a hydrocarbon chain were designed and synthesized. Their surface activity and aggregation behavior in aqueous solution were systematically investigated by surface tension, dynamic light scattering (DLS), and transmission electron microscopy (TEM) techniques at 298 K. The surface tension measurements provided the critical aggregation concentration (CAC) and the surface tension at the CAC (γcac). In addition, with application of the Gibbs adsorption isotherm, the maximum surface excess concentration (Γmax) and the minimum surface area/molecule (Amin) at the air−water interface were estimated. The effect of EO chain length on the surface activity and aggregation behavior was also investigated. It was found that both the γcacand the CAC were lower than those for reported traditional hydrocarbon surfactants. Aggregates of three surfactants, TGA-m(m= 1, 2, and 3), formed in aqueous solutions could be assigned as spherical vesicles as suggested by analysis using DLS and TEM. Moreover the formation of vesicles can be confirmed by the encapsulation of bromophenol blue. These results indicate that these three surfactants have excellent efficiencies of vesicle formation and surface tension reduction in the aqueous phase. [ABSTRACT FROM AUTHOR]

Developing electrocatalysts with low price, high energy efficiency, and universal pH value for hydrogen/oxygen evolution reaction (HER and OER) is very important for the wide application of electrochemical water splitting in hydrogen production. The results of density functional theory show that the interface region of CoP 3 /Ni 2 P heterostructures can significantly boost all of the catalytic performances. High-resolution transmission electron microscopy and X-ray photoelectron spectroscopy were used to confirm the abundant structural defects and the corresponding adjustment of the electronic state, thus ameliorating the activation energy, conductivity, and active area of the catalyst. Benefiting from these, CoP 3 /Ni 2 P heterostructures exhibit superior performance of both HER and OER in a wide pH range. CoP 3 /Ni 2 P can also be used for water splitting (1.557 V at 10 mA cm -2 ) more than 40 h, superior to benchmark pairs of Pt/C and RuO 2 on Ni foam.

As supercapacitor electrode materials, their structures, including specific surface area, instability, and interconnection, determine the electrochemical performances (specific capacitance, cycle stability, and rate performance). In this study, 1T-MoS 2 nanosheets were self-assembled into nanoflowers via a one-pot facile hydrothermal reaction. The nanoflowers retain the excellent electrical conductive performance and the feature of inherent high specific surface area of the nanosheets. For the sheets are interconnected to each other in flower structure, the structure is more stable and the charges are more easily transferred. Thus, compared to the nanosheet electrode, the nanoflower electrode shows the remarkable advantage when used as the electrode of the energy-storage device, whether it is 1T phase or 2H phase in KCl or in KOH. When measured at 0.5 A g -1 in KOH electrolyte, the MoS 2 nanoflower electrode exhibits a high specific capacitance of 1120 F g -1 . At the same time, when cycling 2000 times at a current density of 10 A g -1 , the capacitance retention ratio can reach up to 96%., Competing Interests: The authors declare no competing financial interest., (Copyright © 2019 American Chemical Society.)

Membrane materials with special wettability for separating oil-water mixtures have gradually become one of the research hotspots. However, oily wastewater usually has very strong corrosiveness, which puts forward high requirements for the chemical stability of the separation membrane. In addition, oil droplets may block the pores, resulting in the decrease of separation efficiency or even separation failure. Herein, biomimetic TiO 2 -titanium meshes (BTTMs) with switchable wettability were successfully fabricated by one-step dip coating of poly(vinylidene difluoride) and modified TiO 2 suspension on the titanium meshes. The simple and efficient preparation method will facilitate the promotion of this smart material. Due to the controlled wettability, the BTTM can separate water or oil from an oil-water mixture as required. When the BTTM was immersed in strong corrosive solution or liquid nitrogen, the wettability did not change much, showing the good stability of the BTTM. Furthermore, the BTTM also has self-healing ability, self-recovery anti-oil-fouling properties, and self-cleaning behavior, which help it resist oil pollution and improve its recyclability. This study provides a simple and efficient strategy for fabricating a stable smart surface for on-demand controllable treatment of corrosive oily wastewater.

Traditional oil-water separation materials have to own ultrahigh or ultralow surface energy. Thus, they can only be wetted by one of the two, oil or water. Our experiment here demonstrates that the wettability in oil-water mixtures can be tuned by oil and water initially. Hierarchical voids are built on commercial copper foams with the help of hydrothermally synthesized titanium dioxide nanorods. The foams can be easily wetted by both oil and water. The water prewetted foams are superhydrophilic and superoleophobic under oil-water mixtures, meanwhile the oil prewetted foams are superoleophilic and superhydrophobic. In this paper, many kinds of water-oil mixtures were separated by two foams, prewetted by corresponding oil or water, respectively, combining a straight tee in a high flux, high efficiency, and continuous mode. This research indicates that oil-water mixtures can be separated more eco-friendly and at lower cost.

Ultrathin dual phase nanosheets consisting of alternating spinel Li 4 Ti 5 O 12 (LTO) and rutile TiO 2 (RT) lamellas are synthesized through a facile and scalable hydrothermal method, and the formation mechanism is explored. The thickness of constituent lamellas can be controlled exactly by adjusting the mole ratio of Li:Ti in the original reactants. Alternating insertion of the RT lamellas significantly improves the electrochemical performance of LTO nanosheets, especially at high charge/discharge rates. As anodes in lithium-ion batteries (LIBs), the dual phase nanosheet electrode with the optimized phase ratio can deliver stable discharge capacities of 178.5, 154.9, 148.4, 142.3, 138.2, and 131.4 mA h g -1 at current densities of 1, 10, 20, 30, 40, and 50 C, respectively. Meanwhile, they inherit the excellent cyclic stability of pure spinel LTO and exhibit a capacity retention of 93.1% even after 500 cycles at 50 C. Our results indicate that the alternating nanoscaled lamella structure is a good alternative to facilitate the transfer of both the Li ions and electrons into the spinel LTO, giving rise to an excellent cyclability and fast rate performance. Therefore, the newly prepared carbon-free LTO-RT nanosheets with high safety provide a new opportunity to develop high-power anodes for LIBs.

Five different butynediol-ethoxylate modified polysiloxanes (PSi-EO) were designed and synthesized via two-step reactions: the preparation of low-hydrogen containing silicone oil (LPMHS) by acid-catalyzed polymerization and the following hydrosilylation reaction with 1,4-bis(2-hydroxyethoxy)-2-butyne. The chemical composition of each product was confirmed by FT-IR, (1)H NMR, and (29)Si NMR. The surface activities and aggregation behaviors of PSi-EO surfactants in aqueous solution were studied systematically using surface tension, dynamic light scattering (DLS), transmission electron microscopy (TEM), and contact-angle methodologies. Relatively low critical aggregation concentration (15-34 mg·L(-1)) and surface tension (∼25 mN·m(-1)) were measured for PSi-EO aqueous solution. The rate of surface tension reduction increased both with increasing PSi-EO concentration and with increases in the proportion of hydrophilic moieties within the synthesized compounds. Furthermore, DLS and TEM studies revealed that PSi-EO self-assembled in aqueous solution to form spherical aggregates. Contact-angle measurements conducted upon low-energy paraffin film surfaces demonstrated that PSi-EO exhibited efficient spreading at concentrations above the critical aggregation concentration.

Six novel siloxane-based surface-active ionic liquids (SAILs)--siloxane ammonium carboxylate [Si(n)N(2)-CA(1), (n = 3, 4)]--were designed and synthesized. Their melting points, surface activities, and self-aggregation behavior in aqueous solution were studied. The results showed that because of the bulky hydrophobic siloxane chains at the end of the tail, all six siloxane-based SAILs are room-temperature ionic liquids (RT-SAILs). The introduction of the siloxane group can reduce the melting point of ionic liquids to below room temperature and can promote the micellization and aggregation behavior more efficiently. These siloxane-based SAILs can greatly reduce the surface tension of water, as shown by the critical aggregation concentration (γCAC) values of 20 mN·m(-1); all six siloxane RT-SAILs can form a vesicle spontaneously in aqueous solution, indicating potential uses as model systems for biomembranes and vehicles for drug delivery.

A hierarchical copper structure combining micro- and nanogaps/pores was built up on copper substrate by etching and electrodeposition. The fresh as-deposited copper was easily oxidized in air at room temperature, forming a CuO layer covering on the surface. The surface could be hydrophobized with thiol-modified fluorocarbons, after which it showed a water contact angle as high as 165° ± 2°. This surface could also regain the superhydrophilicity with a zero water contact angel after annealing at 200 °C for 10 min to desorb the low surface energy monolayer of thiol-modified fluorocarbons and reform a CuO layer again on the surface. Repeating the process of adsorption/desorption of the monolayer by modification and annealing, it was successful to fulfill the wettability cycling between superhydrophobicity and superhydrophilicity on the copper surface. The adsorption and desorption mechanism of the monolayer was discussed based on the result of surface chemistry analysis., (© 2011 American Chemical Society)