Latest ArticlesMesoporous titanium nanoparticles (MTNs) have emerged as an important porous semiconductor owning to their large surface area and unique electronic/optical properties. However, the fundamental research for rational manufacturing MTNs in a highly scalable manner remains a challenge. In this study, we report a two-step flash nanocomplexation (FNC) approach to large-scalable generate MTNs through the sequential combination of two multi-inlet vortex mixers. By optimizing the concentrated titanium precursor, polyethylene glycol (PEG)-functionalized silane amount and pH, we have been able to produce MTNs with small particle size (31.5 nm), larger surface area (416.9 m²/g) and pore volume (0.59 cm3/g). Different from the traditional MTNs bulk, FNC-produced MTNs exhibited well-controlled manner and exceptional photocatalytic and antibacterial properties. Importantly, the optimized MTNs outperformed commercial P25 not only in protecting ultraviolet A (UVA)-exposed skin, but also in treating P. aeruginosa-infected wound. We believe that the high controllability and scalability of sequential flash nanocomplexation method offers great opportunities in enhancing the performance of mesoporous titanium nanoparticles.
Electrochemical conversion of nitrate (NO3−) to ammonia (NH3) can target two birds with one stone well, in NO3−-containing sewage remediation and sustainable NH3 production. However, single metal-based catalysts are difficult to drive high-efficient NO3− removal due to the multi-electron transfer steps. Herein, we present a tandem catalyst with simple structure, Cu-Co binary metal oxides (Cu-Co-O), by engineering intermediate phases as catalytic active species for NO3− conversion. Electrochemical evaluation, X-ray photoelectron spectroscopy, and in situ Raman spectra together suggest that the newly-generated Cu-based phases was prone to NO3− to NO2− conversion, then NO2− was reduced to NH3 on Co-based species. At an applied potential of −1.1 V vs. saturated calomel electrode, the Cu-Co-O catalyst achieved NO3−-N removal of 90% and NH3 faradaic efficiency of 81% for 120 min in 100 mL of 50 mg/L NO3−-N, consuming only 0.69 kWh/mol in a two-electrode system. This study provides a facile and efficient engineering strategy for developing high-performance catalysts for electrocatalytic nitrate conversion.
A rhodium/diphosphine-catalyzed asymmetric cross-dehydrogenative coupling between sulfoximines and dihydrosilanes has been achieved. This is the first report on the enantioselective N-silylation of sulfoximines. The protocol gives access to a variety of Si-stereogenic N-silylated sulfoximines in decent yield (up to 99%) with excellent stereoselectivity (up to 99%), featuring high atom economy, and a cleaner manner with H2 as the sole byproduct. The obtained bis-Si-stereogenic monohydrosilane product can be further converted into the corresponding chiral polymer with pendant sulfoximine groups.
In an era where the concept of green development is deeply rooted, magnesium (Mg) alloy as a light metal has a long-term development prospect in the process of energy saving, emission reduction and environmental improvement. However, anti-corrosion performance of Mg alloy is poor due to the high chemical activity and low equilibrium potential, which limits the development of Mg alloy products. Herein, three-dimensional mesopore hollow polypyrrole spheres (MHPS) were prepared, and the MHPS was inserted into the middle of the stacked hexagon boron nitride (h-BN) lamellae, which allowed the h-BN to be separated forming a further composite with abundant pore structure. Subsequently, the MHPS/h-BN-OH composite was uniformly sprayed on the Mg alloy surface via simple spraying method to form the superhydrophobic surface (SHS). Finally, the slippery liquid infused porous surface (SLIPS) was successfully fabricated by applying drops of silicone lubricant on the superhydrophobic coating surface. After a series of characterization and testing, the results showed that the stacking of h-BN lamellae was significantly reduced after h-BN was successfully embedded by MHPS. In addition, the fabricated SLIPS have excellent self-cleaning, mechanical stability, anti-icing and anti-corrosion properties. Therefore, the method of embedding polymer microspheres not only offers a new strategy for h-BN exfoliation, but also the successful prepared SLIPS largely retards the corrosion of Mg alloy while providing new ideas for the development of SLIPS.
Doyle-Kirmse rearrangement reactions have received continuous attention as an important method for constructing complex chemical structures. Herein, we disclosed an efficient rhodium-catalyzed Doyle-Kirmse rearrangement reaction, which can simultaneously construct CC bonds and CX (X = S/Se) bonds using sulfoxonium ylides as starting materials to obtain sulfur- or selenium-containing compounds. This strategy is characterized by the safer and greener carbene precursor, high yields and broad substrate scope, possessing a wide range of application.
Sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) are the most promising alternatives to lithium-ion batteries, and thus have drawn intensive research attention. Porous carbon materials from different precursors have been widely used as anode materials owing to their compatible storage effectiveness of both larger radii sodium and potassium ions. However, the differential bonding behaviors of Na and K ions with porous carbon-based anode are the significant one worth investigating, which could provide a clean picture of alkali ions storage mechanism. Therefore, in this work, we prepare a porous carbon network derived from sawdust (SDC) wastes, to further analyze the differences on sodium and potassium ions storage behaviors in terms of bond-forming process. It is found that, as-prepared SDC anodes could deliver stable sodium and potassium storage capacities, however, there are notable distinctions in terms of electrochemical behaviors and diffusion processes. By virtue of ex-situ XRD and Raman spectroscopy, the phase transition reaction of potassium ions could be well-observed, and the results shows that the multiple intercalated compounds was formed in SDC network during ions insertion, further resulting in slower diffusion kinetics and larger resistance compared to non-bonded process of sodium ions storage. This study provides more insights into the differences between sodium and potassium ions storage, as well as the energy storage mechanism of porous carbon as anodes for secondary batteries.
A facile TfOH-catalyzed oxidative cyclization of allyl compounds and isocyanide has been developed with the assistance of DDQ, where isocyanide is used as the crucial "N" and "CN" sources. Highly functionalized 2-cyanopyrroles are constructed efficiently through a new formal [3 + 2] mode, demonstrating diverse reactivity and synthetic utility in organic chemistry. 2-Cyanopyrrole is converted into a nucleobase analogue of Remdesivir and 5H-pyrrolo[2, 1-a]isoindole through a three-step or a two-step sequence, respectively. This protocol features broad substrate scope, operational simplicity and good functional group tolerance.
Palladium-exchanged chabazite (Pd-CHA) zeolites as passive NOx adsorbers (PNAs) enable efficient purification of nitrogen oxides (NOx) in cold-start diesel exhausts. Their commercial application, however, is limited by the lack of facile preparation method. Here, high-performance CHA-type Pd-SAPO-34 zeolite was synthesized by a modified solid-state ion exchange (SSIE) method using PdO as Pd precursor, and demonstrated superior PNA performance as compared to Pd-SAPO-34 prepared by conventional wet-chemistry strategies. Structural characterization using Raman spectroscopy and X-ray diffraction revealed that the SSIE method avoided water-induced damage to the zeolite framework during Pd loading. Mechanistic investigations on the SSIE process by in situ infrared spectroscopy and X-ray photoelectron spectroscopy disclosed that, while PdO precursor was mainly converted to Pd2+ cations coordinated to the zeolite framework by consuming the -OH groups of the zeolite, a portion of PdO could also undergo thermal decomposition to form highly dispersed Pd0 clusters in the pore channels. This simplified and scalable SSIE method paves a new way for the cost-effective synthesis of defect-free high-performance Pd-SAPO-34 zeolites as PNA catalysts.
Microchannels enable the fast and efficient mixing of multiphase fluids. In this study, a millimeter-scale three-dimensional (3D) circular cyclone-type microreactor was designed for the mixing. The flow characteristics and mixing intensity were simulated by computational fluid dynamics simulations at a flow rate range of 12–96 mL/min using a water/ethyl acetate system. In the 3D variable-diameter structure, the microreactor induced paired opposite vortices and abruptly changed the local pressure to achieve a stable turbulent effect within the theoretical range of laminar flow. Tracer injection simulations indicated that sufficient mixing units successfully promote fluid dispersion. Diazo-coupling experiments showed a segregation index of XS = 0. 00,039 within a residence time of 9 s. Extraction experiments on the n-butanol/succinic acid/water system showed that the 3D circular cyclone-type microreactor achieved 100% extraction efficiency (E) in 4.25 s, and the overall volume mass transfer coefficient (KLa) reached 0.05–1.5 s-1 in 12–96 mL/min. The isolated yield of the phase transfer alkylation and oxidation reactions in the 3D circular cyclone-type microreactor achieved 99% within 36 s, which was superior to the coil microreactor and batch reactor.
Light-driven nitrogen fixation to produce ammonia is a green and economical technology of nitrogen reduction but is still quite challenging, especially in an air atmosphere without any sacrificial reagents. Herein, we demonstrate efficient photocatalytic nitrogen fixation using water and air directly by loading lanthanide–transition metal (4f–3d) cluster NdCo3 on two-dimensional P-doped graphitic carbon nitrides (PCN) material surface. Benefiting from the increase in the number of nitrogen vacancies (NVs) and highly matched band gap structure and excellent hole trapping ability of clusters, the NdCo3/PCN photocatalyst exhibits efficient nitrogen reduction activity with 371 (in air) and 825 µmol h−1 g−1 (in pure nitrogen) without any sacrificial reagents. The introduction of potassium sulfate inhibits hydrogen production and promotes nitrogen reduction activation. This work suggests that anchoring precisely structured clusters on 2D materials may enhance photocatalytic nitrogen reduction under normal temperature and pressure.
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