Au-Ag alloy nanoparticles supported on mesoporous aluminosilicate have been prepared by one-pot synthesis using hexadecyltrimethylammonium bromide (CTAB) both as a stabilizing agent for nanoparticles and as a template for the formation of mesoporous structure. The formation of Au-Ag alloy nanoparticles was confirmed by X-ray diffraction (XRD), ultraviolet-visible (UV-vis) spectroscopy, and transmission electron microscopy (TEM). Although the Au-Ag alloy nanoparticles have a larger particle size than the monometallic gold particles, they exhibited exceptionally high activity in catalysis for low-temperature CO oxidation. Even at a low temperature of 250 K, the reaction rate can reach 8.7 x 10(-6) mol.g(cat.)(-1).s(-1) at an Au/Ag molar ratio of 3/1. While neither monometallic Au@MCM-41 nor Ag@MCM-41 shows activity at this temperature, the Au-Ag alloy system shows a strongly synergistic effect in high catalytic activity. In this alloy system, the size effect is no longer a critical factor, whereas Ag is believed to play a key role in the activation of oxygen.

Magnetic, durable, and superhydrophobic polyurethane (PU) sponges were fabricated by chemical vapor deposition (CVD) of tetraethoxysilane (TEOS) to bind the Fe3O4 nanoparticles tightly on the sponge and then dip-coating in a fluoropolymer (FP) aqueous solution. The sponges were characterized using scanning electron microscopy and other analytical techniques. The effects of CVD time of TEOS and FP concentration on wettability, mechanical properties, oil absorbency, and oil/water selectivity of the sponges were also investigated. The sponges exhibit fast magnetic responsivity and excellent superhydrophobicity/superoleophilicity (CAwater = 157° and CAoil ≈ 0°). The sponges also show very high efficiency in oil/water separation and could, driven by a magnet, quickly absorb floating oils on the water surface and heavy oils under water. Moreover, the PU@Fe3O4@SiO2@FP sponges could be used as membranes for oil/water separation and for continuous separation of large amounts of oil pollutants from the water surface with the help of a pump. The in turn binding of Fe3O4 nanoparticles, SiO2, and FP can also improve mechanical properties of the PU sponge. The sponges maintain the superhydrophobicity even when they are stretched with 200% strain or compressed with 50% strain. The sponges also show excellent mechanical stability, oil stability, and reusability in terms of superhydrophobicity and oil absorbency. The magnetic, durable, and superhydrophobic PU sponges are very promising materials for practical oil absorption and oil/water separation.

A novel poly(acrylic acid)/attapulgite superabsorbent composite was synthesized by graft copolymerization reaction of acrylic acid (AA) on attapulgite micropowder using N,NЈ-methylenebisacrylamide (MBA) as a crosslinker and ammonium persulfate (APS) as an initiator in aqueous solution. The effects on water absorbency of such factors as reaction temperature, initial monomer concentration, degree of neutralization of AA, amount of crosslinker, initiator, and attapulgite were investigated. These crosslinked superabsorbent composites were characterized by thermogravimetetric analysis and scanning electron microscopy. The graft copolymerization reaction of AA on attapulgite micropowder was characterized by FTIR. The water absorbencies for these superabsorbent composites in water and saline solutions were investigated and water-retention tests were carried out. Results obtained from this study show that the water absorbency of the superabsorbent composite synthesized under optimal synthesis conditions with an attapulgite content of 10% exhibited an absorption of 1017 g H 2 O/g sample and 77 g H 2 O/g sample in distilled water and in 0.9 wt % NaCl solution, respectively.

Through periodic density functional theory (DFT) calculations we have investigated the catalytic mechanism of CO oxidation on an Ir1/FeO x single-atom catalyst (SAC). The rate-determining step in the catalytic cycle of CO oxidation is shown to be the formation of the second CO2 between the adsorbed CO on the surface of Ir1/FeO x and the dissociated O atom from gas phase. Comparing with Pt1/FeO x catalyst, the reaction activation barrier for CO oxidation is higher by 0.62 eV and the adsorption energy for CO molecule is larger by 0.69 eV on Ir1/FeO x . These results reveal that Ir1/FeO x catalyst has a lower activity for CO oxidation than Pt1/FeO x , which is consistent with our experimental results. The results can help to understand the fundamental mechanism of monodispersed surface atoms and to design highly active single-atom catalysts.

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A facile method for preparing porous polydimethylsiloxane (PDMS) sponges is reported. The PDMS sponges are fabricated by the polymerization of the PDMS prepolymer and a curing agent in dimethicone using NaCl microparticles as the hard templates. The porous structure of the PDMS sponges is controllable simply by regulating the weight ratio of prepolymer to dimethicone and the size of the NaCl microparticles. The PDMS sponges feature high compressibility and stretchability, excellent superhydrophobicity/superoleophilicity, as well as high chemical and thermal stability. The PDMS sponge can completely recover its original shape even after 50 cycles of 90% strain. The elongation at breaking the sponge is as high as 97%. The PDMS sponge is superhydrophobic with a water contact angle of 151.5 but can be easily wetted by oils.The sponge also exhibits excellent repellency to corrosive aqueous liquids. The flexibility and superhydrophobicity of the sponge remain unchanged even after keeping in liquid nitrogen or at 250 C for 24 h. Long-term immersion in various organics has no obvious influence on superhydrophobicity, oil absorbency, or weight of the sponge. The PDMS sponge can selectively absorb a large amount of floating oils on the water surface and heavy oils under the water, and furthermore, is reusable. Moreover, the PDMS sponge swells quickly after the adsorption of oils, which makes it a promising material for plugging oil leakages.

Nepenthes pitcher inspired anti-wetting coatings, fl uoro-SNs/Krytox, are successfully fabricated by the combination of fl uoro-silicone nanofi laments (fl uoro-SNs) and Krytox liquids, perfl uoropolyethers. Fluoro-SNs with different microstructure are grown onto glass slides using trichloromethylsilane by simply repeating the coating step, and then modifi ed with 1 H, 1 H, 2 H, 2 Hperfl uorodecyltrichlorosilane. Subsequently, the Krytox liquid is spread on the fl uoro-SNs coatings via capillary effect. The fl uoro-SNs/Krytox coatings feature ultra-low sliding angle for various liquids, excellent stability, and transparency. The sliding speed of liquid drops on the fl uoro-SNs/Krytox coating is obviously slower than on the lotus inspired superhydrophobic and superoleophobic coatings, and is controlled by composition of the coating (e.g., morphology of the fl uoro-SNs, type of Krytox and its thickness) and properties of the liquid drops (e.g., density and surface tension). In addition, the self-cleaning property of the fl uoro-SNs/Krytox coating is closely related to properties of liquid drops and dirt.

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