Nano Research最新文献

Size hierarchy is a distinct feature of nanogold-catalysts as it can strongly affect their performance in various reactions. We developed a simple method to generate Au_nS_m nanoclusters of different sizes by thermal treatment of an Au₁₄₄(PET)₆₀ (PET: phenylethanethiol) parent cluster. These clusters, deposited on activated carbon, exhibit excellent catalytic performance in the hydrochlorination of acetylene. _In-situ ultraviolet laser dissociation high-resolution mass spectrometry of the parent cluster in the presence of acetylene revealed a remarkable cluster size-dependence of acetylene adsorption, which is a crucial step in the hydrochlorination. Systematic density functional theory calculations of the reaction pathways on the differently-sized clusters provide deeper insight into the cluster size dependence of the adsorption energies of the reactants and afforded a scaling relationship between the adsorption energy of acetylene and the co-adsorption energies of the reactants (C₂H₂ and HCl), which could enable a qualitative prediction of the optimal Au_nS_m cluster for the hydrochlorination of acetylene.

Cu-based chalcogenide materials exhibit significant promise for the development of Zn-metal-free anode materials for aqueous Zn-ion batteries (AZIBs). Here, we present the establishment of an efficient and universal strategy that capitalizes on the pyrolysis of copper nanoclusters to fabricate conversion-type Cu₇S₄ anodes engineered for AZIBs, showcasing outstanding electrochemical performance. Furthermore, by exploiting ligand engineering, we enable the precise control of both the type of molecular fragments generated during nanocluster pyrolysis, thus enabling the manipulation of vacancy concentrations and ion/electron migration in the resultant pyrolysis products. In contrast to the direct pyrolysis of metal salts and ligands, the products derived from copper nanoclusters exhibit enhanced specific capacity, rate performance, and overall stability. This research offers valuable insights for the development of novel electrode materials through the pyrolysis of atomically precise nanoclusters.

Olefin hydrogenation under mild condition is crucial and challenging for industrial applications. Herein, defective UiO-66(Ce) was constructed by using cyanuric acid as the molecular etching “scissors” and further to synthesize heterogeneous catalyst with highly dispersed RuNi nanoparticles (Ru₁Ni_1.5@UiO-66(Ce)-12 h). The construction of Ce-O-Ru/Ni heterogeneous interfaces and Ni–Ru bonds provide electron transfer channels from Ce-oxo clusters and Ni species to Ru species. Furthermore, the microenvironment and electronic structure of Ru⁰ active sites were synergistically regulated by adjusting the content of metal-organic frameworks (MOFs) defects and Ni promoter, thereby enhancing the adsorption and activation ability of H–H and C=C bonds. Therefore, Ru₁Ni_1.5@UiO-66(Ce)-12 h achieved dicyclopentadiene saturated hydrogenation (100% conversion) to tetrahydrodicyclopentadiene (∼ 100% selectivity) under mild condition (35 °C, 1 MPa) with only 25 min. Meanwhile, the sample exhibited excellent structural stability after 6 cycles test. This study provides a promising strategy for the rational design of remarkable noble metal-based catalysts for practical applications.

Hydrogel, as one of potential soft materials for articular cartilage, has encountered pressing obstacles, such as insufficient mechanical properties, poor lubrication, and easy to wear. To tackle these, we propose a strong yet slippery polyvinyl alcohol/chitosan (PVA/CS) hydrogel with dual-physically crosslinked networks by harnessing freeze-thawing, salting-out, annealing, and rehydration. High mechanical properties of PVA/CS hydrogel can be readily regulated by adjusting proportion of PVA/CS and annealing temperature. The optimized hydrogel exhibits high mechanical properties with tensile strength of ∼ 19 MPa at strain of 550%, compression strength of ∼ 11 MPa at small strain of 39%, and outstanding toughness and antifatigue owing to the robust physical interactions, including hydrogen bonds, crystallization, and ionic coordination. Moreover, the equilibrium hydrogel shows low friction coefficient of ∼ 0.05 against Al₂O₃ ball under the condition of 30 N, 1 Hz, with water as the tribological medium, which is close to the lubrication performance of native cartilage. And meanwhile, the proposed cartilage-like slippery hydrogel displays stable long-term lubrication performance for 1 × 10⁵ reciprocating cycles without destructive wear and structure damage. It is therefore believed that the biocompatible cartilage-like slippery hydrogel opens innovative scenarios for developing cartilage-mimicking water-lubricated coating and biomedical implants with satisfactory load-bearing and lubrication performance.

The problems of electromagnetic wave (EMW) pollution in X and Ku bands (8–18 GHz) are becoming more and more serious. Therefore, it is urgent to design EMW absorbing materials with high-efficiency such as thin thickness, lightweight, wide bandwidth and strong EMW absorption. Inspired by the biomorph of sea cucumber, Nb₂CT_x MXene@Co nitrogen-doped carbon nanosheet arrays@carbon fiber aerogels (Nb₂CT_x@Co-NC@CFA, Nb₂CT_x = niobium carbide) were constructed by self-assembly, in-situ chemical deposition and subsequent pyrolysis. The carbon fiber aerogel, as the basic skeleton of sea cucumber, forms lightweight three-dimensional interconnected conductive network, enhances the dielectric loss and extends the multiple reflection and absorption paths of EMW. As the tentacles of sea cucumber surface, Nb₂CT_x MXene and Co nitrogen-doped carbon nanosheet arrays exist rich heterogeneous interfaces, which play an important role in improving EMW polarization loss and optimizing impedance matching. The minimum reflection loss (RL_min) of Nb₂CT_x@Co-NC@CFA reaches −54.7 dB at 9.84 GHz (2.36 mm) with a low filling ratio of 10 wt.% and the effective absorption bandwidth (EAB) of Nb₂CT_x@Co-NC@CFA reaches 2.96 GHz (8.48–11.44 GHz) with 2.36 mm and 5.2 GHz (12.8–18 GHz) with 1.6 mm, covering most of X and Ku bands by adjusting thickness. The radar cross section (RCS) value of Nb₂CT_x@Co-NC@CFA is 26.64 dB·m², which is lower than that of the perfect electrical conductor (PEC), indicating that Nb₂CT_x@Co-NC@CFA can effectively decrease the probability of the target being detected by the radar detector. This work provides ideas for design and development of EMW absorbing materials with high-efficiency EMW absorption in X and Ku bands.

Nowadays, increasing emissions of hazardous chemicals cause serious environmental pollution. The advanced oxidation processes (AOPs), which produce numbers of reactive oxygen species (ROS), are one of the most widely used technologies for degrading refractory pollutants in aqueous phase. Among these, Fenton reaction including both homogeneous and heterogeneous processes, has received increasing attention for water treatment. In this review, various nanomaterials with different size such as nanocrystals, nanoparticles (e.g., iron-based minerals, bimetallic oxides, zero-valent iron, quantum dots) and metal-based single atom catalysts (SACs) applied in homogeneous and heterogeneous Fenton reactions, as well as the corresponding catalytic mechanisms will be systematically summarized. Several factors including the morphology, chemical composition, geometric/electronic structures influence the catalytical behavior simultaneously. Here, the recent research advancement including the advantages and further challenges in homogeneous and heterogeneous Fenton system will be introduced in detail. Furthermore, developments for different nanomaterials, from nanocrystals, nanoparticles (minerals, bimetallic oxides represented by Fe-based catalysts, and nanosized zero valent iron materials) to SACs will be discussed. Some representative catalysts for Fenton reaction and their applications will be presented. In addition, commonly-used supports (e.g., graphene oxide, g-C₃N₄, and carbon nanotubes) and metal-organic frameworks (MOFs)/derivatives and metal-support interaction for improving Fenton-like performance will be introduced. Finally, different types of catalysts for Fenton reaction are compared and their practical application and operational costs are summarized.

Compared with thermodynamically equilibrium supramolecular assemblies, non-equilibrium assemblies from the same building blocks have attracted increasing attentions because their diverse structures and dynamic natures may impart the assemblies with novel functionalities. However, facile access to non-equilibrium assemblies remains a formidable challenge. Herein, we endeavored to exploit various solvent-anti-solvent methods to achieve it using peptide amphiphile C16-VVAAEE-NH₂ as a model. Through systematical utilization of dialysis, ultrasonic and stirring-dropping methods, as well as tuning of processing parameters, we demonstrated the successful formation of diverse non-equilibrium nanostructures with distinct morphologies and structures that significantly deviate from the thermodynamically favored twisted long ribbons. Additionally, these metastable nanostructures ultimately underwent spontaneous transformation into thermodynamically stable states. The transformation processes of three representative non-equilibrium assemblies were also demonstrated and characterized in detail using transmission electron microscopy, circular dichroism spectrum, and thioflavin T fluorescence spectrum. Furthermore, non-equilibrium assemblies exhibited various degrees of cytotoxic effects, which may stem from their spontaneous, dynamic transformation and interactions with cellular membranes. This study offers valuable approaches for direct access to diverse non-equilibrium supramolecular nanostructures from self-assembling peptide, and also has implications for the development of advanced materials with unprecedented biological functions.

The energy density of batteries can be increased by using high-load cathode material matched with sodium (Na) metal anode. However, the large polarization of the battery under such harsh conditions will promote the growth of Na dendrites and side reactions. Carbon materials are regarded as ideal modify layers on Na metal anode to regulate the Na⁺ plating/stripping behavior and inhibit the Na dendrites and side reactions due to their light weight, high stability and structural adjustability. However, commonly used carbon nanotubes and carbon nanofibers cannot enable these modified Na metal anodes to operate stably in full batteries with a high-load cathode (> 15 mg·cm⁻²). The most fundamental reason is that abundant polar functional groups on the surface bring serious side reactions and agglomerations lead to uneven Na⁺ flow. Here, a proof-of-concept study lies on fabrications of carbon nanospheres with small amount of polar functional groups and sodiophobic components on the surface of Na metal anode, which significantly enhances the uniformity of the Na⁺ plating/stripping. The assembled symmetric battery can cycle stability for 1300 h at 3 mA·cm⁻²/3 mAh·cm⁻². The full battery with high-load Na₃V₂(PO₄)₃ (30 mg·cm⁻²) maintains a Coulombic efficiency of 99.7% after 100 cycles.

Chemical vapor deposition (CVD) has shown great promise for the large-scale production of high-quality graphene films for industrial applications. Atomic-scale theoretical studies can help experiments to deeply understand the graphene growth mechanism, and serve as theoretical guides for further experimental designs. Here, by using density functional theory calculations, ab-initio molecular dynamics simulations, and microkinetic analysis, we systematically investigated the kinetics of hydrogen constrained graphene growth on Cu substrate. The results reveal that the actual hydrogen-rich environment of CVD results in CH as the dominating carbon species and graphene H-terminated edges. CH participated island sp² nucleation avoids chain cyclization process, thereby improving the nucleation and preventing the formation of non-hexameric ring defects. The graphene growth is not simply C-atomic activity, rather, involves three main processes: CH species attachment at the growth edge, leading to a localized sp³ hybridized carbon at the connecting site; excess H transfer from the sp³ carbon to the newly attached CH; and finally dehydrogenation to achieve the sp² reconstruction of the newly grown edge. The threshold reaction barriers for the growth of graphene zigzag (ZZ) and armchair (AC) edges were calculated as 2.46 and 2.16 eV, respectively, thus the AC edge grows faster than the ZZ one. Our theory successfully explained why the circumference of a graphene island grown on Cu substrates is generally dominated by ZZ edges, which is a commonly observed phenomenon in experiments. In addition, the growth rate of graphene on Cu substrates is calculated and matches well with existing experimental observations.

Messenger RNA (mRNA) is a type of RNA that carries genetic information from DNA to the ribosome, where it is translated into proteins. mRNA has emerged as a powerful platform for development of new types of medicine, especially after the clinical approval of COVID-19 mRNA vaccines. Chemical modification and nanoparticle delivery have contributed to this success significantly by improving mRNA stability, reducing its immunogenicity, protecting it from enzymatic degradation, and enhancing cellular uptake and endosomal escape. Recently, substantial progresses have been made in new modification chemistries, sequence design, and structural engineering to generate more stable and efficient next-generation mRNAs. These innovations could further facilitate the clinical translation of mRNA therapies and vaccines. Given that numerous review articles have been published on mRNA nanoparticle delivery and biomedical applications over the last few years, we herein focus on overviewing recent advances in mRNA chemical modification, mRNA sequence optimization, and mRNA engineering (e.g., circular RNA and multitailed mRNA), with the aim of providing new perspectives on the development of more effective and safer mRNA medicines.