Nano Materials Science最新文献

Dialysis plays a crucial role in the purification of nanomaterials but its impact on the structural properties of carbon nanomaterials was never investigated. Herein, a carbon-based nanomaterial generated electrochemically in potassium phosphate buffer, was characterized before and after dialysis against pure water. It is shown that dialysis affects the size of the carbon domains, structural organization, surface functionalization, oxidation degree of carbon, and grade of amorphicity. Accordingly, dialysis drives the nanomaterial organization from discrete roundish carbon domains, with sizes ranging from 70 to 160 nm, towards linear stacking structures of small nanoparticles (<15 ​nm). In parallel, alcohol and ether (epoxide) surface groups evolve into more oxidized carbon groups (e.g., ketone and ester groups). Investigation of the as-prepared nanomaterial by electron paramagnetic resonance (EPR) revealed a resonance signal consistent with carbon-oxygen centred radicals.

Additionally, this study brings to light the selective affinity of the carbon nanomaterial under study to capture Na⁺ ions, a property greatly enhanced by the dialysis process, and its high ability to trap oxygen, particularly before dialysis. These findings open new perspectives for the application of carbon-based nanomaterials and raise awareness of the importance of structural changes that can occur during the purification of carbon-based nanomaterials.

As a alternative for natural enzymes, nanozymes has shown enzyme-like activity and selectivity in the field of various kinds of biomedical application, which has attracted considerable research interest. Recently, single-atom catalysts (SACs) have been extensively studied due to their similar active centers, coordination environment and better stability to natural enzymes. Metal-organic frameworks (MOFs) have been demonstrated as highly promising precursors for the synthesis of various types of SACs. MOF-derived SACs can not only significantly enhance the catalytic activity, but also improve the selectivity of nanozymes due to tunable coordination environment and structure, thereby receiving widespread attention in biomedicine. This review provided an overview of the preparation strategies for MOF-derived SACs, and then detailed the latest research progress of the SACs in the biomedical field for cancer, antibacterial, antioxidation and biosensors. Finally, the challenges and potential future opportunities of MOF-derived SACs in biomedical applications are proposed.

A feasible approach to rectify the world's energy demand using sustainable development of adequate energy generation and storage technologies in a single channel. In this respect, we made a holistic approach with a bi-functional electrode material to perform effectively in energy generation and storage applications. MoS₂ nanosheets were produced by the eco-friendly method and reduced graphene oxide is used to prepared by carbon soot which is derived from castor oil. The prepared soot and rGO were combined with MoS₂ nanosheets using a simple sonication method. The as-prepared sample was introduced in the supercapacitor and DSSC application. The combination MoS₂@rGO provides an enhanced conversion efficiency of 11.81 ​% and the reproducibility of DSSC is also studied. Further, MoS₂@rGO is used to fabricate an asymmetric supercapacitor to investigate its real-time application. The device produced the maximum power density (1666.6 ​mW/kg) and energy density (25.69 ​mWh/Kg) at 1 A/g. The asymmetric supercapacitor device holds a cyclic stability of 81.4 % for 5000 cycles and it powered up an LED device for 4 ​min.

High-efficiency seawater electrolysis is impeded by the low activity and low durability of oxygen evolution catalysts due to the complex composition and competitive side reactions in seawater. Herein, a heterogeneous-structured catalyst is constructed by depositing NiFe-layered double hydroxides (NiFe-LDH) on the substrate of MXene (V₂CT_x) modified Ni foam (NF), and abbreviated as NiFe-LDH/V₂CT_x/NF. As demonstrated, owing to the intrinsic negative charge characteristic of V₂CT_x, chlorine ions are denied entry to the interface between NiFe-LDH and V₂CT_x/NF substrate, thus endowing NiFe-LDH/V₂CT_x/NF catalyst with high corrosion resistance and durable stability for 110 ​h at 500 ​mA ​cm⁻². Meanwhile, the two-dimensional structure and high electrical conductivity of V₂CT_x can respectively enlarge the electrochemical active surface area and guarantee fast charge transfer, thereby synergistically promoting the catalytic performance of NiFe-LDH/V₂CT_x/NF in both deionized water electrolyte (261 ​mV at 100 ​mA ​cm⁻²) and simulated seawater electrolyte (241 ​mV at 100 ​mA ​cm⁻²). This work can guide the preparation of oxygen evolution catalysts and accelerate the industrialization of seawater electrolysis.

Multifunctional metastructure integrated broadband microwave absorption and effective mechanical resistance has attracted much attention. However, multifunctional performance is limited by the lack of theoretical approaches to integrated design. Herein, a multi-layer impedance gradient honeycomb (MIGH) was designed through theoretical analysis and simulation calculation, and fabricated using 3D printing technique. A theoretical calculation strategy for impedance gradient structure was established based on the electromagnetic parameter equivalent method and the multi-layer finite iterative method. The impedance of MIGH was analyzed by the theoretical calculation strategy to resolve the broadband absorption. Intrinsic loss mechanism of matrix materials and distributions of electric fields, magnetic fields and power loss were analyzed to investigate the absorption mechanism. Experimental results indicated that a 15 ​mm thick designed metastructure can achieve the absorption more than 88.9% in the frequency range of 2-18 ​GHz. Moreover, equivalent mechanical parameters of MIGH was calculated by integral method according to the Y-shaped model. Finite Element analysis of stress distributions were carried out to predict the deformation behavior. Mechanical tests demonstrate that MIGH achieved the compression modulus of 22.89 ​MPa and flexure modulus of 17.05 ​MPa. The integration of broadband electromagnetic absorption and effective mechanical resistance was achieved by the proposed design principle and fabrication methodology.

The need to combine various metals in light-weight constructions requires the development of coatings that prevent galvanic corrosion. Layered double hydroxides (LDHs) can be an example of such coatings, which were previously successfully obtained in situ on individual materials. In addition, the possibility of LDH growth (including LDH growth in the presence of chelating agents) on the surface of plasma electrolytic oxidation (PEO)-coated metals was previously shown. This PEO ​+ ​LDH combination could improve both corrosion and mechanical characteristics of the system. The possibility of LDHs formation in situ on the surface of PEO-coated friction stir welded (FSW) magnesium-aluminum materials (AZ31/AA5754 system was selected as a model one) was demonstrated in the presence of 1,3-diamino-2-hydroxypropane-N,N,N’,N’-tetraacetic acid (DHPTA) as a chelating agent, which was selected based on analysis of respective metal-ligand compounds stability. LDHs growth was achieved under ambient pressure without addition of carbonates in the electrolyte. The effectiveness of the resulting coating is shown both for corrosion resistance and hardness.

Marine biofouling seriously affects human marine exploitation and transportation activities, to which marine antifouling (AF) coatings are considered to be the most cost-effective solution. Since the mid-20th century, human beings have dedicated their efforts on developing AF coatings with long cycle and high performance, leading to a large number of non-target organisms' distortion, death and marine environmental pollution. Polydimethylsiloxane (PDMS), is considered as one of the representative environment-friendly AF materials thanks to its non-toxic, hydrophobic, low surface energy and AF properties. However, PDMS AF coatings are prone to mechanical damage, weak adhesion strength to substrate, and poor static AF effect, which seriously restrict their use in the ocean. The rapid development of various nanomaterials provides an opportunity to enhance and improve the mechanical properties and antifouling properties of PDMS coating by embedding nanomaterials. Based on our research background and the problems faced in our laboratory, this article presents an overview of the current progress in the fields of PDMS composite coatings enhanced by different nanomaterials, with the discussion focused on the advantages and main bottlenecks currently encountered in this field. Finally, we propose an outlook, hoping to provide fundamental guidance for the development of marine AF field.

In response to thermal runaway (TR) of electric vehicles, recent attention has been focused on mitigation strategies such as efficient heat dredging in battery thermal management. Thermal management with particular focus on battery cooling has been becoming increasingly significant. TR usually happened when an electric vehicle is unpowered and charged. In this state, traditional active battery cooling schemes are disabled, which can easily lead to dangerous incidents due to loss of cooling ability, and advanced passive cooling strategies are therefore gaining importance. Herein, we developed an enhanced thermal radiation material, consisting of ∼1 ​μm thick multilayered nano-sheet graphene film coated upon the heat dissipation surface, thereby enhancing thermal radiation in the nanoscale. The surface was characterized on the nanoscale, and tested in a battery-cooling scenario. We found that the graphene-based coating's spectral emissivity is between 91 ​% and 95 ​% in the mid-infrared region, and thermal experiments consequently illustrated that graphene-based radiative cooling yielded up to 15.1 ​% temperature reduction when compared to the uncoated analogue. Using the novel graphene surface to augment a heat pipe, the temperature reduction can be further enlarged to 25.6 ​%. The new material may contribute to transportation safety, global warming mitigation and carbon neutralization.

Nanoscale hierarchically porous metal-organic frameworks (NH-MOFs) synergistically combine the advantages of nanoscale MOFs and hierarchically porous MOFs, resulting in remarkable characteristics such as increased specific surface area, greater porosity, and enhanced exposure of active sites. Herein, nanoscale hierarchically porous UIO-66 (UIO-66_X) was synthesized using a defect-induced strategy that employed ethylene diamine tetraacetic acid (EDTA) as a modulator. The introduced EDTA occupies the coordination sites of organic ligands, promoting the formation and growth of UIO-66 crystal nuclei and inducing defects during synthesis. The as-synthesized UIO-66_X crystals exhibit a uniform distribution with an average size of approximately 100 ​nm. In addition, the total pore volume attains a remarkable value of 0.95 ​cm³ ​g⁻¹, with mesopores constituting 36.8 % of the structure. Furthermore, the porosities of UIO-66_X can be easily tuned by controlling the molar ratio of EDTA/Zr⁴⁺. In addition, the as-synthesized UIO-66_X exhibits excellent adsorption capacities for n-hexane (344 ​mg ​g⁻¹) and p-xylene (218 ​mg ​g⁻¹), which are 44.5 % and 27.5 % higher than those of conventional UIO-66, respectively. Finally, the adsorption behavior of n-hexane and p-xylene molecules in UIO-66_X was investigated using density functional theory simulations.

With characteristics and advantages of functional composite materials, they are commendably adopted in numerous fields especially in oxygen electrocatalysis, which is due to the significant synergies between various components. Herein, a novel bifunctional oxygen electrocatalyst (Co-CNT@COF-Pyr) has been synthesized through in-situ growth of covalent organic frameworks (COFs) layers on the outer surface of highly conductive carbon nanotubes (CNTs) followed by coordination with Co(Ⅱ). For electrocatalytic OER, Co-CNT@COF-Pyr reveals a low overpotential (438 ​mV) in alkaline electrolyte (1.0 ​M aqueous solution of KOH) with a current density of 10 ​mA ​cm⁻², which is comparable to most discovered COF-based catalysts. For electrocatalytic ORR, Co-CNT@COF-Pyr exhibits a low H₂O₂ yield range (9.0 ​%–10.1 ​%) and a reaction pathway close to 4e⁻ (n ​= ​3.82–3.80) in alkaline electrolyte (0.1 ​M aqueous solution of KOH) within the test potential range of 0.1–0.6 ​V vs. RHE, which is superior to most reported COF-based catalysts. Hence, this research could not only offer an innovative insight into the construction of composites, but also facilitate the practical application of renewable fuel cells, closed water cycle, and rechargeable metal-air batteries.