Au-Pt bimetallic nanoparticles formation via viologen-mediated reduction on polymeric nanospheres

Hollow and mesoporous aluminosilica-encapsulated Pt-CoOx for the selective hydrogenation of substituted nitroaromatics

Hollow and mesoporous aluminosilica nanoreactors (HMANs) with Pt-CoO_x cores (∼4.7 nm) and hollow aluminosilica shells (∼50 nm) were designed by a selective etching method. The Pt-CoO_x@HMANs demonstrate a greatly enhanced activity and selectivity for the hydrogenation of various substituted nitroaromatics compared to Pt@HMANs and Pt-CoO_x@SiO₂.

The fabrication of hollow ZrO2 nanoreactors encapsulating Au-Fe2O3 dumbbell nanoparticles for CO oxidation

Nanosized Au catalysts suffer from serious sintering problems during synthesis or catalytic reactions at high temperatures. In this work, we integrate dumbbell-shaped Au-Fe₃O₄ heterostructures into hollow ZrO₂ nanocages to make Au-Fe₂O₃@ZrO₂ yolk-shell nanoreactors with high activity as well as ultra-high sintering resistance for high-temperature CO oxidation. The synthesis starts with the fabrication of a (Au-Fe₃O₄)@SiO₂@ZrO₂ core-shell nanostructure with a Au-Fe₃O₄ dumbbell nanoparticle (DB) core and SiO₂/ZrO₂ double shells, followed by calcination and the selective removal of the inner SiO₂ shell with alkaline solution to obtain Au-Fe₂O₃@ZrO₂ nanoreactors. The retained ZrO₂ hollow (outer) shells protect the Au NPs from aggregation at temperatures up to 900 °C and show excellent long-term stability. Compared to Au@ZrO₂ yolk-shell nanoreactors, Au-Fe₂O₃@ZrO₂ shows improved activity in CO oxidation due to the active Au-Fe₂O₃ interface. This strategy can be extended to other yolk-shell nanoreactors with various nanocomposites and for different catalytic reactions.

Sulfonated Polystyrene Nanoparticles as Oleic Acid Diethanolamide Surfactant Nanocarriers for Enhanced Oil Recovery Processes

The aim of this study is the evaluation of partially sulfonated polystyrene nanoparticles (SPSNP) efficiency as nanocarriers for a non-ionic surfactant, oleic acid diethanolamide (OADA), in the reduction of the surfactant losses and the increase of oil recovery. The synthesized oleic acid diethanolamide was characterized by FTIR, ¹H NMR, ¹³C NMR, surface tension (γ = 36.6 mN·m⁻¹, CMC = 3.13 × 10⁻⁴ M) and interfacial tension of mineral oil/OADA aqueous solutions (IFT_eq = 0.07 mN·m⁻¹). The nanoparticles (SPSNP) were obtained by emulsion polymerization of styrene, DVB and sodium 4-styrenesulfonate (St-S) in the presence of OADA aqueous solution and were characterized by FTIR and PCS. The results show that the presence of ionic groups in the polymer structure promoted a better nanoparticles suspensions′ stability, smaller particles production and more pronounced IFT reduction. The SPSNP obtained with an OADA concentration twenty times its CMC and 0.012 mol % of St-S presented a particle size around 66 nm and can act as efficient nanocarriers decreasing the water/oil interfacial tension to low values (0.07 mN·m⁻¹) along the time, when in contact with the oil. Transport and oil recovery tests of the nanocarriers systems in an unconsolidated sand porous medium test show that the SPSNP do inhibit surfactant adsorption onto sand particles surface and induced an increase of oil recovery of up to about 13% relative to the water flooding oil recovery, probably due to a synergistic effect between the nanoparticles and surfactant action at the water/oil interface.

Sensing properties of light-emitting single walled carbon nanotubes prepared via click chemistry of ylides bound to the nanotube surface

Fluorescent single walled carbon nanotube-mediated sensors with a detection limit of ∼10⁻⁸ M for nitrophenol based chemical warfare agents and environmental pollutants.

A facile one-pot route to cationic cellulose nanocrystals

Pyridinium-grafted-cellulose nanocrystals were prepared by a simple one-pot reaction using 4-(1-bromoethyl/bromomethyl)benzoic acid, pyridine and cellulose nanocrystals (CNCs). The grafting consists of an esterification reaction between 4-(1-bromoethyl/bromomethyl)benzoic acid and CNCs and a nucleophilic attack on the C-Br bond of 4-(1-bromoethyl/bromomethyl)benzoic acid by pyridine. This reaction simplifies existing cationization methods, which leads to a higher grafting density while retaining the CNC crystallinity.