Search

As an emerging zero-dimensional nano crystalline porous material, porous organic cages (POCs) with soluble properties in organic solvents, are promising candidates as molecular fillers in mixed matrix membranes (MMMs). The pore structure of POCs should be adjusted to trigger efficient gas separation performance, and the interaction between filler and matrix should be optimized. In this work, ionic liquid (IL) was introduced into the molecular fillers of CC3, to construct the IL@CC3/PIM-1 membrane to effectively separate CO2 from CH4. The advantages of doping IL include: (1) narrowing the cavity size of POCs from 4.4 to 3.9 Å to enhance the diffusion selectivity, (2) strengthening the CO2 solubility to heighten the gas permeability, and (3) improving the compatibility between filler and matrix to upgrade membrane stability. After the optimization of the membrane composite, the IL@CC3/PIM-1-10% membrane possesses the CO2 permeability of 7868 Barrer and the CO2/CH4 selectivity of 73.4, which compared to the CC3/PIM-1-10% membrane, improved by 15.9% and 106.2%, respectively. Furthermore, the membrane has maintained a stable separation performance at varied temperatures and pressures during the long-term test. The proposed method offers an efficient way to improve the performance of POCs-based MMMs in gas separation. [ABSTRACT FROM AUTHOR]

It is of great significance to develop high-temperature anhydrous proton conducting materials. Herein, we report a new strategy to significantly enhance the proton conductivity of covalent organic frameworks (COFs) through expanding the dimensionality of proton conduction. Three COF-based composites, COF-1@PA, COF-2@PA, and COF-3@PA (PA: phosphoric acid), are prepared by PA doping of three COFs with similar pore sizes but different amounts of hydrophilic groups. With the increase of hydrophilic groups, COFs can load more PA because of the enhanced hydrogen–bonding interactions between PA and the frameworks. powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and two-dimensional (2D) solid-state nuclear magnetic resonance (NMR) analyses show that PA can not only enter the channels of COF-3, but also insert into its 2D interlayers. This expands the proton conduction pathways from one-dimensional (1D) to three-dimensional (3D), which greatly improves the proton conductivity of COF-3. Meanwhile, the confinement effect of 1D channels and 2D layers of COF-3 also makes the hydrogen-bonded networks more orderly in COF-3@PA-30 (30 µL of PA loaded on COF-3). At 150 °C, COF-3@PA-30 exhibits an ultrahigh anhydrous proton conductivity of 1.4 S·cm−1, which is a record of anhydrous proton conductivity reported to date. This work develops a new strategy for increasing the proton conductivity of 2D COF materials. [ABSTRACT FROM AUTHOR]

The heterostructure of transition metal nanocrystal on two-dimensional (2D) materials exhibits unique physical and chemical properties through various interfacial interactions. It has been established that the atomic structure and strain in the vicinity of the interface determine the band structure and phonon modes of the nanocrystal, regulating the optical and electrical properties of such heterostructures. Hence, metal—support interfacial engineering is a demonstrated approach to acquiring desired properties of the nanocrystals. However, a fundamental understanding of the interfacial structures remains elusive and precise control of the interactions has yet achieved. Herein, we explore the regulation of interface on MoS2 supported Pt nanocrystals which were prepared by reducing ultrasonic dispersed potassium chloroplatinate. The Pt-MoS2 heterostructure interface was systematically studied by aberration corrected transmission electron microscopy. Three types of Pt-MoS2 interfaces with distinct atomic configurations were identified. The strain within the Pt nanocrystals is sensitive to the atomic configuration of the supporting MoS2, which regulates the size of the Pt nanocrystals. These results provide insights on tuning of nanocrystal strain, paving the way for precise control of 2D semiconductor heterostructures. [ABSTRACT FROM AUTHOR]

Formic acid oxidation (FAO) is a typical anode reaction in fuel cells that can be facilitated by modulating its direct and indirect reaction pathways. Herein, PtAu bimetallic nanoparticles loaded onto Co and N co-doping carbon nanoframes (CoNC NFs) were designed to improve the selectivity of the direct reaction pathway for efficient FAO. Based on these subtle nanomaterials, the influences of elemental composition and carbon-support materials on the two pathways of FAO were investigated in detail. The results of fuel cell tests verified that the appropriate amount of Au in PtAu/CoNC can promote a direct reaction pathway for FAO, which is crucial for enhancing the oxidation efficiency of formic acid. In particular, the obtained PtAu/CoNC with an optimal Pt/Au atomic ratio of 1:1 (PtAu/CoNC-3) manifests the best catalytic performance among the analogous obtained Pt-based electrocatalysts. The FAO mass activity of the PtAu/CoNC-3 sample reached 0.88 A ⋅ mg Pt − 1 , which is 26.0 times higher than that of Pt/C. The results of first-principles calculation and CO stripping jointly demonstrate that the CO adsorption of PtAu/CoNC is considerably lower than that of Pt/CoNC and PtAu/C, which indicates that the synergistic effect of Pt, Au, and CoNC NFs is critical for the resistance of Pt to CO poisoning. This work is of great significance for a deeper understanding of the oxidation mechanism of formic acid and provides a feasible and promising strategy for enhancing the catalytic performance of the catalyst by improving the direct reaction pathway for FAO. [ABSTRACT FROM AUTHOR]

A dual-mode DNA sensor was constructed to detect nucleic acid sensitively and selectively. Based on dendritic porous silica nanoparticles (DPSNs) and hybridization chain reaction (HCR) amplification strategy, the fabricated DNA sensor showed good sensitivity with low detection limits down to 2.18 pM and 4.02 pM by fluorescence (excited at 488 nm and emitted at 508 nm) and personal glucose meter (PGM) assays, respectively. This dual-mode detection of DNA offered superior reliability and accuracy and could meet the requirements of different testing environments, including laboratory confirmation and portable detection. Moreover, the impact of nanoparticles morphology on detection performance was also discussed. Due to the center-radial pores, DPSNs had high curvature morphology, which improved the coverage capacity, footprint, and deflection angle of probes. This work fabricated a dual-mode DNA sensor and revealed the relationship between morphology and detection performance, which brought new insights in novel biosensor development. [ABSTRACT FROM AUTHOR]