Nano Research最新文献

The development of highly efficient separation technology for the purification of natural gas by removing ethane (C₂H₆) and propane (C₃H₈) is a crucial but challenging task to their efficient utilization in the chemical industry and social life. Here, we report three isomorphic ultra-microporous metal-organic frameworks (MOFs), M-pyz (M = Fe, Co, and Ni, and pyz = pyrazine) referred to as Fe-pyz, Co-pyz, and Ni-pyz, respectively, which possess high density of open metal sites and suitable pore structure. Compared with the benchmark materials reported, M-pyz not only has high adsorption capacities of C₂H₆ and C₃H₈ at low pressure (up to 51.6 and 63.7 cm³·cm⁻³), but also exhibits excellent C₃H₈/CH₄ and C₂H₆/CH₄ ideal adsorption solution theory (IAST) selectivities, 111 and 25, respectively. Theoretical calculations demonstrated that the materials’ separation performance was driven by multiple intermolecular interactions (hydrogen bonding interactions and van der Waals effect) between gas molecules (C₂H₆ and C₃H₈) and the M-pyz binding sites. And, dynamic breakthrough experiments verified the superior reusability and practical separation feasibility for the ternary CH₄/C₂H₆/C₃H₈ mixtures. Furthermore, M-pyz can be synthesized rapidly and on a large scale at room temperature. This work presents a series of promising MOFs adsorbents to efficiently purify natural gas and promotes the industrial development process of MOFs materials.

Fine and ultrafine particles possess great potential for industrial applications ascribed from their huge specific surface area and ability to provide good gas–solid contact. However, these powders are inherently cohesive, making it challenging to achieve smooth flow and fluidization. This challenge can be well-resolved by nanoparticle modulation (nano-modulation), where a small amount of nanoparticles is uniformly mixed with the cohesive fine/ultrafine powders. Through nano-modulation, the fluidization system of cohesive powders exhibits distinguishable minimum fluidization velocity, enlarged bed expansion ratio (particularly the dense phase expansion), and scarcer, smaller, and slower moving bubbles, indicating improved flow and fluidization quality. The purpose of the current work is to systematically summarize the state-of-the-art progress in the fluidization and utilization of fine and ultrafine particles via the nanoparticle modulation method. Accordingly, a broader audience can be enlightened regarding this promising fine/ultrafine particle fluidization technology, so as to provoke their attention and encourage interdisciplinary integration and industry-academia collaborative research.

The green synthesis of nitrate (NO₃⁻) via electrocatalytic nitrogen oxidation reaction (NOR) is a promising strategy for artificial nitrogen fixation, which shows great advantages than traditional nitrate synthesis based on Haber–Bosch and Ostwald processes. But the poor N₂ absorption, high bond energy of N≡N (941 kJ·mol⁻¹), and competing multi-electron-transfer oxygen evolution reaction (OER) limit the activity and selectivity. Herein, we fabricated MXene-derived irregular TiO_2−x nanoparticles anchored Cu nanowires (Cu-NWs) electrode for efficient electrocatalytic nitrogen oxidation, which exhibits a NO₃⁻ yield of 62.50μ_g·h⁻¹·mg_cat⁻¹ and a Faradaic efficiency (FE) of 22.04%, and a significantly enhanced NO₃⁻ yield of 92.63 μ_g·h⁻¹·mg_cat⁻¹, and a FE of 40.58% under vacuum assistance. The TiO_2−x/Cu-NWs electrode also shows excellent reproducibility and stability under optimal experimental conditions. Moreover, a Zn-N₂ reaction device was assembled with TiO_2−x/Cu-NWs as an anode and Zn plate as a cathode, obtaining an extremely high NO₃⁻ yield of 156.25 μ_g·h⁻¹·mg_cat⁻¹. The Zn-nitrate battery shows an open circuit voltage (OCV) of 1.35 V. This work provides novel strategies for enhancing the performance of ambient N₂ oxidation to obtain higher NO₃⁻ yield.

Trimethylphenol is an organic toxic byproduct of industrial process, which is difficult to be eliminated through conventional degradation without harsh conditions. In this work, a sulfite-based oxidation process activated by ZnO-embedded hydrogel was studied for the degradation of 2,4,6-trimethylphenols in the ambient conditions. The ZnO/Na₂SO₃ oxidative system can effectively degrade trimethylphenol via the generation of radicals such as ({rm{S}}{{rm{O}}_4}^{. - }), OH^·, and ({rm{S}}{{rm{O}}_3}^{. - }). The presence of hydrogel matrix facilitates the distribution and recyclability of ZnO catalysts while maintaining high degradation kinetics and little leaching of metal ions. Results suggest the promising potential of ZnO-hydrogel in wastewater treatment with good performance in terms of pH sensitivity, anion interference, recyclability, etc. The combination of ZnO catalysts, hydrogel, and sulfite-based advanced oxidation process may provide essential support for the current treatment of alkylated phenols with strong potential in the commercial scale-ups.

Emerging as a prominent area of focus in energy conversion and storage technologies, the development of highly active metal-based single-atom catalysts (SACs) holds great significance in searching alternatives to replace precious metals toward the efficient, stable, and low-cost hydrogen evolution reaction (HER), as well as the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR). Combining the tremendous tunability of ligand and coordination environment with rich metal-based electrocatalysts can create breakthrough opportunities for achieving both high stability and activity. Herein, we propose a novel and stable holey graphene-like carbon nitride monolayer g-C₁₆N₅ (N₄@g-C₁₆N₃) stoichiometries interestingly behaving as a natural substrate for constructing SACs ((TM-N₄)@g-C₁₆N₃), whose evenly distributed holes map rich and uniform nitrogen coordination positions with electron-rich lone pairs for anchoring transition metal (TM) atoms. Then, we employed density functional theory (DFT) calculations to systematically investigate the electrocatalytic activity of (TM-N₄)@g-C₁₆N₃ toward HER/OER/ORR, meanwhile considering the synergistic modulation of H-loading and O-coordination ((TM-N_xO_4−x)@g-C₁₆N₃-H₃, x = 0–4). Together a “four-step procedure” screening mechanism with the first-principles high-throughput calculations, we find that (Rh-N₄) and (Ir-N₂O_2-II) distributed on g-C₁₆N₃-H₃ can modulate the adsorption strength of the adsorbates, thus achieving the best HER/OER/ORR performance among 216 candidates, and the lowest overpotential of 0.098/0.3/0.46 V and 0.06/0.48/0.45 V, respectively. Additionally, the d-band center, crystal orbital Hamilton population (COHP), and molecular orbitals are used to reveal the OER/ORR activity source. Particularly, the Rh/Ir-d orbital is dramatically hybridized with the O-p orbital of the oxygenated adsorbates, so that the lone-electrons incipiently locate at the antibonding orbital pair up and populate the downward bonding orbital, allowing oxygenated intermediates to be adsorbed onto (TM-N_xO_4−x)@g-C₁₆N₃-H₃ appropriately.

Molecular semiconductors (MSCs), characterized by a longer spin lifetime than most of other materials due to their weak spin relaxation mechanisms, especially at room temperature, together with their abundant chemical tailorability and flexibility, are regarded as promising candidates for spintronic applications. Molecular spintronics, as an emerging subject that utilizes the unique properties of MSCs to study spin-dependent phenomena and properties, has attracted wide attention. In molecular spintronic devices, MSCs play the role as medium for information transport, process, and storage, in which the efficient spin inject–transport process is the prerequisite. Herein, we focus mainly on summarizing and discussing the recent advances in theoretical principles towards spin transport of MSCs in terms of the injection of spin-polarized carriers through the ferromagnetic metal/MSC interface and the subsequent transport within the MSC layer. Based on the theoretical progress, we cautiously present targeted design strategies of MSCs that contribute to the optimization of spin-transport efficiency and give favorable approaches to exploring accessional possibilities of spintronic materials. Finally, challenges and prospects regarding current spin transport are also presented, aiming to promote the development and application of the rosy and energetic field of molecular spintronics.

For metal nanofilms composed of nanocrystals, the multiple deformation mechanisms will coexist and bring unique and complex elastic-plastic and fracture mechanical properties. By successfully fabricating large quantities of uniform doubly-clamped suspended gold (Au) nanobeams with different thicknesses and nanograin sizes, we obtain full-spectrum mechanical features with statistical significance by combining atomic force microscopy (AFM) nanoindentation experiments, nonlinear theoretical model, and numerical simulations. The yield and breaking strengths of the Au nanobeams have a huge increase by nearly an order of magnitude compared with bulk Au and exhibit strong nonlinear effects, and the corresponding strong-yield ratio is up to 4, demonstrating extremely high strength reserve and vibration resistance. The strong-yield ratio gradually decreases with decreasing thickness, identifying a conversion of the failure type from ductile to brittle. Interestingly, the Hall–Petch relationship has been identified to be still valid at the nanoscale, and K in the equation reaches 4.8 Gpa·nm^1/2, nearly twice of bulk nanocrystalline Au, which is ascribed to the coupling effect of nanocrystals and nanoscale thickness.

A scalable strategy for the convenient and rapid preparation of nitrogen-doped carbon-coated iron-based alloy catalysts was developed. By controlling the type and amount of metal salts in the precursor, various types of nitrogen-doped carbon-coated alloy catalysts can be prepared in a targeted manner. Fe₂Ni₂@CN materials with small particle sizes and relatively homogeneous basic sites showed promising results in the N-alkylation reaction of benzyl alcohol with aniline (optimum yield: 99%). It is worth noting that the catalyst can also be magnetically separated and recovered after the reaction, and its performance can be regenerated through simple calcination. Furthermore, it was confirmed by kinetic experiments that the activation of C–H at the benzyl alcohol benzylic position is the rate-determining step (RDS). According to density flooding theory calculations, Fe₂Ni₂@CN catalysts require less energy than other materials (Fe@CN and Ni@CN) for the RDS (dehydrogenation reaction) process. Therefore N-alkylation reactions are more easily carried out on Fe₂Ni₂@CN catalysts, which may be the reason for the best catalytic activity of Fe-Ni alloy materials. These carbon-coated alloy materials will show great potential in more types of heterogeneous catalysis.

The solar-driven reduction of CO₂ into valuable products is a promising method to alleviate global environmental problems and energy crises. However, the low surface charge density limits the photocatalytic conversion performance of CO₂. Herein, a polymeric carbon nitride (PCN) photocatalyst with Zn single atoms (Zn₁/CN) was designed and synthesized for CO₂ photoreduction. The results of the CO₂ photoreduction studies show that the CO and CH₄ yields of Zn₁/CN increased fivefold, reaching 76.9 and 22.9 µmol/(g·h), respectively, in contrast to the unmodified PCN. Ar⁺ plasma-etched X-ray photoelectron spectroscopy and synchrotron radiation-based X-ray absorption fine structure results reveal that Zn single atom is mainly present in the interlayer space of PCN in the Zn–N₄ configuration. Photoelectrochemical characterizations indicate that the interlayer Zn–N₄ configuration can amplify light absorption and establish an interlayer charge transfer channel. Light-assisted Kelvin probe force microscopy confirms that more photogenerated electrons are delivered to the catalyst surface through interlayer Zn–N₄ configuration, which increases its surface charge density. Further, in-situ infrared spectroscopy combined with density functional theory calculation reveals that promoted surface charge density accelerates key intermediates (⋆COOH) conversion, thus achieving efficient CO₂ conversion. This work elucidates the role of internal single atoms in catalytic surface reactions, which provides important implications for the design of single-atom catalysts.