Specific Nanostructures Research Articles

Theoretical superlubricity and its friction stability of amorphous carbon film induced by simple surface graphitization

Amorphous carbon (a-C) film as one of the most promising superlubricious materials arouses much attention from technical and industrial fields. However, the superlubricious state of a-C film strongly depends on the formation of special nanostructures or components, increasing the difficulty and complexity of the preparation process. Reducing the friction coefficient of a-C film to superlubricity is still a challenge for industrial scale-up. Herein, a simple and effective approach is proposed to achieve superlubricity by in-situ formation of graphitized structure at a-C surface via fast annealing. Results reveal that the friction property closely depends on the graphitized degree of mated a-C surfaces and the friction coefficient below 0.01 or even 0.001 can be obtained for the highly graphitized system. In particular, under extreme working condition, it also demonstrates excellent stability and reliability of superlubricious behavior. This is not only mainly attributed to the decrease of spacing distance between mated graphitized structures following the high repulsive force, but also related to the tight anchoring of graphitized structure to the intrinsic a-C. In addition, compared to the widely applied surface passivation approach, the graphitization modification of a-C surface exhibits higher effectiveness in superlubricity without deteriorating the intrinsic mechanical properties of a-C film.

A high mass loading flexible electrode with a sheet-like Mn3O4/NiMoO4@NiCo LDH on a carbon cloth for supercapacitors.

Mass loading is an important parameter to evaluate the application potential of active materials in high-capacity supercapacitors. Synthesizing active materials with high mass loading is a promising strategy to improve high performance energy storage devices. Preparing electrode materials with a porous structure is of significance to overcome the disadvantages brought by high mass loading. In this work, a Mn3O4/NiMoO4@NiCo layered double hydroxide (MO/NMO/NiCo LDH) positive electrode is fabricated on a carbon cloth with a high mass loading of 20.4 mg cm-2. The MO/NMO/NiCo LDH presents as a special three-dimensional porous nanostructure and exhibits a high specific capacitance of 815 F g-1 at 1 A g-1. Impressively, the flexible supercapacitor based on the MO/NMO/NiCo LDH positive electrode and an AC negative electrode delivers a maximum energy density of 22.5 W h kg-1 and a power density of 8730 W kg-1. It also retains 60.84% of the original specific capacitance after bending to 180° 600 times. Moreover, it exhibits 76.92% capacitance retention after 15 000 charge/discharge cycles. These results make MO/NMO/NiCo LDH one of the most attractive candidates of positive electrode materials for high-performance flexible supercapacitors.

Topology regulation of nanomedicine for autophagy-augmented ferroptosis and cancer immunotherapy

Iron accumulation and lipid peroxidation form the basis of ferroptosis, potentially circumventing the limitations of apoptosis in cancer treatment. Owing to the lack of potent ferroptosis inducers, the development of efficient ferroptosis-based therapeutic agents and protocols against cancers is highly challenging. Inspired by the topological effect of nanoparticles in modulating cellular function/status, a specific tetrapod ferroptosis-inducer iron-palladium (FePd) nanocrystal was rationally engineered for physically activated autophagy-augmented ferroptosis and enhanced cancer immunotherapy. Specifically, the tetrapod FePd nanocrystal featured strong peroxidase-/glutathione oxidase-mimicking bioactivities, which promoted cancer cell ferroptosis. The special spiky morphology and nanostructure of the FePd nanocrystal simultaneously induced autophagy, which augmented ferroptosis in cancer cells and triggered the release of inflammatory cytokines in macrophages for strengthening anti-PD-L1-antibody mediated immunotherapy, synergistically achieving the maximal antineoplastic effect in three tumor-bearing animal models. This unique physical activation strategy for efficient cancer treatment via precise morphological tuning represents a paradigm for nanomedicine design for efficient tumor treatment.

Self-Assembly of Antimicrobial Peptide-Based Micelles Breaks the Limitation of Trypsin.

Targeting the limitation of antimicrobial peptides (AMPs) application in vivo, self-assembled AMPs library with specific nanostructures is expected to gradually overtake monomer AMPs libraries in the future. Peptide polymers are fascinating self-assembling nanoscale structures that have great advantage in biomedical applications because of their satisfactory biocompatibility and versatile properties. Herein, we describe a strategy for inducing the self-assembly of T9W into nanostructured antimicrobial micelles with evidently improved pharmacological properties, that is, PEGylation at the C-terminal of T9W (CT9W1000), an antibacterial biomaterial that self-assembles in aqueous media without exogenous excipients, has been developed. Compared with parental molecular, the CT9W1000 is more effective against Pseudomonas aeruginosa, and its antibacterial spectrum had also been broadened. Additionally, CT9W1000 micelles had higher stability under salt ion, serum, and acid-base environments. Importantly, the self-assembled structure is highly resistant to trypsin degradation, probably allowing T9W to be applied in clinical settings in the future. Mechanistically, by acting on membranes and through supplementary bactericidal mechanisms, CT9W1000 micelles contribute to the antibacterial process. Collectively, CT9W1000 micelles exhibited good biocompatibility in vitro and in vivo, resulting in highly effective treatment in a mouse acute lung injury model induced by P. aeruginosa PAO1 without drug resistance. These advances may profoundly accelerate the clinical transformation of T9W and promote the development of a combination of peptide-based antibiotics and PEGylated nanotechnology.

Black Silver Nanocubes@Amino Acid-Encoded Highly Branched Gold Shells with Efficient Photothermal Conversion for Tumor Therapy.

Cancers are among the leading causes of death currently. Conventional radiotherapy and chemotherapy are of limited use in the treatment of some tumors due to their high toxicity and drug resistance. Plasma photothermal therapy has attracted extensive attention for the treatment of tumors due to photothermal properties of plasmonic nanoparticles, such as gold (Au) nanoparticles, to achieve local hyperthermia with low toxicity and high efficiency. Herein, we report a kind of special black noble-metal core-shell nanostructure, with silver (Ag) nanocubes as the core and amino acid-encoded highly branched Au nanorods as the shells (l-CAg@Au and d-CAg@Au). The proposed growth of l-CAg@Au and d-CAg@Au nanocomposites was an amino acid-encoded Stranski-Krastanov mode. Both l-CAg@Au and d-CAg@Au exhibited outstanding photothermal conversion compared to the core-shell structure without amino acids (Ag@Au). d-CAg@Au possessed the best photothermal conversion efficiency (87.28%) among the composite nanoparticles. The antitumor therapeutic efficacy of as-prepared samples was evaluated in vitro and in vivo, and apoptosis analysis was done via flow cytometry. This work reports novel insights for the preparation of special bimetallic branched structures and broadens the application of metal nanomaterials in photothermal tumor therapy.

Engineering SERS Properties of Silicon Nanotrees at the Nanoscale

Large specific surface area nanostructures are desirable in a wide range of sensing applications due to their longer light-trapping path and increased absorption. Engineering of the specific nanotree structure which possesses a high branch density turned out to be challenging from the experimental point of view, and certainly not adequately explored. This paper shows how to design substrates with a silicon nanotree structure for surface-enhanced Raman spectroscopy (SERS) applications. Silicon nanotrees were synthesized by a Ag-Au nanocluster-catalyzed low-pressure chemical vapor deposition method (LPCVD). By the presented approaches, it is possible to manipulate branches’ number, length and thickness. The synthesized nanostructures are flexible after immersion in water which improves SERS performance. The amount of sputtered metal played a key role in preserving the flexibility of the nanotree structure. The obtained substrates with highly fractal nanostructure were tested on 4-mercaptophenylboronic acid (MPBA) to match the optimal SERS parameters. The silicon nanotrees fabrication, and particularly obtained SERS substrates plated with Ag and Au nanoparticles, demonstrated good features and a promising approach for further sensor development.

Formation mechanism and thermal stability of γ' and γ" compact co-precipitated nanostructure in directed energy deposited Ni-based alloy

In order to understand the formation mechanism of a special nanostructure of γ' and γ" co-precipitated phase which present an important potential in the improvement of high thermal stability, strength and ductility in the superalloy, the influence of the atomic ratio of (Al+Ti)/Nb on the microstructures of the Ni-Cr-Al-Ti-Nb alloys has been investigated using laser directed energy deposition (DED). As the ratio of (Al+Ti)/Nb increases in the as-deposited and heat-treated alloy, the precipitation ability of γ' phase in the alloy is improved, accompanied with a reduction in the precipitation of γ" phase. When this ratio reaches 1.5 with the alloy composition of Ni-13.5Cr-5.26Al-1.95Ti-4.8Nb (at.%), the γ' and γ" co-precipitated nanostructure with the pattern of γ" phase attaching to six surfaces of the cubic γ' phase is generally produced in the as-deposited and heat-treated alloy. Furthermore, it was revealed that Ti element has the critical effect on the formation of this compact co-precipitated nanostructure.

Specific Metal Nanostructures toward Electrochemical CO2 Reduction: Recent Advances and Perspectives

AbstractElectrochemically converting CO2 (CO2 reduction reaction(CO2RR)) to value‐added fuels is an advanced technology to effectively alleviate global warming and the energy crisis. However, thermodynamically high energy barriers, sluggish reaction kinetics, and inadequate CO2 conversion rate as well as poor selectivity of target products and rapid materials degradation severely limit its further large‐scale application, which highlights the importance of high‐performance electrocatalysts. Metal nanomaterials, due to their intrinsically high but still insufficient reactivity, selectivity, and stability, have been brought to the forefront and have lead to many reviews from various points of view. However, reviews which comprehensively unravel the importance and excellence of specific metal nanostructures and their associated properties for CO2RR are quite limited. To bridge this gap, various specific monometal and bimetal nanostructures are summarized, with an emphasis on the deep understanding of crystal orientation, surface structure, surface crystallography, surface modification, and many associated effects benefiting from the constructed specific metal nanostructures as well as the intrinsic relationships of specific metal nanostructure‐property‐CO2RR activities. Finally, the challenges and the perspectives to advance CO2RR are proposed to pay particularly more attention to architecture evolution during CO2RR with in situ/operando techniques, high‐throughput theoretical computations, and facile synthetic strategies with high yield and production for scale‐up applications.

Amorphous Cobalt Phosphate Porous Braced-Frame Nanocubes as Highly Efficient Supercapacitor Electrodes

It is extremely urgent to develop novel electrode materials with large capacity, high charge–discharge speed, and cycle stability for the particular application of supercapacitors in electric vehicles. Cobalt-based phosphate materials have attracted increasing attention due to their outstanding properties. Herein, cobalt phosphate with a braced-frame nanocube morphology consisting of amorphous nanoparticles is synthesized through a one-step ion-exchange method using Prussian Blue Analog Co3[Co(CN)6]2 nanocubes as precursors. Benefiting from the special nanostructure, this material shows a specific capacitance of up to 539.2 F g–1 at 1 A g–1, a capacitance retention of 92% even at 8 A g–1, and remarkable cycle stability characteristics, with a capacity preservation of 89.1% after 3000 charge–discharge cycles at 2 A g–1. The kinetic mechanism demonstrates that the diffusion-controlled procedure has made a great contribution to the large capacitance. This study will be helpful for the development of new electrode materials for supercapacitors.

DNA Nanostructure-Guided Plasmon Coupling Architectures

DNA Nanostructure-Guided Plasmon Coupling Architectures

Laser-processed antiadhesive bionic combs for handling nanofibers inspired by nanostructures on the legs of cribellate spiders.

Nanofibers are drawing the attention of engineers and scientists because their large surface-to-volume ratio is favorable for applications in medicine, filter technology, textile industry, lithium-air batteries, and optical sensors. However, when transferring nanofibers to a technical product in the form of a random network of fibers, referred to as nonwoven fabric, the stickiness of the freshly produced and thus fragile nanofiber nonwoven remains a problem. This is mainly because nanofibers strongly adhere to any surface because of van der Waals forces. In nature, there are animals that are actually able to efficiently produce, process, and handle nanofibers, namely cribellate spiders. For that, the spiders use the calamistrum, a comb-like structure of modified setae on the metatarsus of the hindmost (fourth) legs, to which the 10-30 nm thick silk nanofibers do not stick due to a special fingerprint-like surface nanostructure. In this work, we present a theoretical model of the interaction of linear nanofibers with a sinusoidally corrugated surface. This model allows for a prediction of the adhesive interaction and, thus, the design of a suitable surface structure to prevent sticking of an artificially nonwoven of nanofibers. According to the theoretical prediction, a technical analogon of the nanoripples was produced by ultrashort pulse laser processing on different technically relevant metal surfaces in the form of so-called laser-induced periodic surface structures (LIPSS). Subsequently, by means of a newly established peel-off test, the adhesion of an electrospun polyamide fiber-based nonwoven was quantified on such LIPSS-covered aluminium alloy, steel, and titanium alloy samples, as well as on polished (flat) control samples as reference and, additionally, on samples with randomly rough surfaces. The latter revealed that the adhesion of electrospun nanofiber nonwoven is significantly lowered on the nanostructured surfaces compared with the polished surfaces.

Metallic-Bonded Pt-Co for Atomically Dispersed Pt in the Co4N Matrix as an Efficient Electrocatalyst for Hydrogen Generation.

Exploiting highly efficient electrocatalysts toward hydrogen evolution reaction (HER) has a significant role in the mass production of hydrogen energy through water electrolysis. Herein, ginkgo leaf-like Co4N coupled with trace Pt with metallic bond Pt-Co on nickel foam via solvothermal, tannic acid treated, and nitridation procedures for HER (T-Pt-Co4N) is developed. It only requires low overpotentials of 31 mV and 27 mV to achieve 10 mA cm-2 in alkaline and neutral electrolytes, respectively, surpassing the benchmark Pt/C and previously reported values. Moreover, it presents excellent long-term stability in the studied media and also can drive overall water splitting under the assistance of sustainable energies. The specific nanostructure favors the acceleration of the electrocatalytic process by exposing abundant active sites and providing numerous mass transport channels during the catalytic process. Moreover, experimental and theoretical calculation demonstrate that the atomic Pt coordinates with Co to form metallic bond Pt-Co also act as crucial role to boost the electrocatalytic performance by optimizing the reaction kinetics for HER.

Synthesis and characterization of pregelatinized starch modified C-S-H: Inspired by the historic binders

• A pregelatinized starch modified C-S-H were prepared to mimic the historic binders. • The modification of pregelatinized starch on C-S-H is dependent on the Ca/Si ratio. • Some pregelatinized starch/C-S-H shows a special stacking nanostructure similar to shells. • Pregelatinized starch have the potential of healing the defects of C-S-H silicate chains. • Pregelatinized starch affect the percentage of stacking units and the nanomechanical properties. The historic starch-lime mixtures are characterized by the hybrid of organic substance and inorganic materials. Inspired by the features of historic binders, this paper presents a novel method by introducing the pregelatinized corn-starch into the stacking of C-S-H nanoparticles. The nanostructure and mechanical properties of the modified C-S-H were evaluated. The results show that the pregelatinized starch interacts with the C-S-H through hydrogen bonding and change the C-S-H silicates chains. The Ca/Si ratios highly determines the crystalline nanostructure and elastic modulus of pregelatinized starch/C-S-H particles. When the Ca/Si is 0.83 and the addition of pregelatinized starch is 0.1%, the pregelatinized starch/C-S-H particles shows a “shells” morphology, in which the rod-like C-S-H stacking with the pregelatinized starch as the “binder”. The pregelatinized starch also affects the percentage of stacking units with different nanomechanical property. This paper provides theorical and basic data for creating new green cementitious materials.

Oxygen promoted hydrogen production from formaldehyde reforming with oxide-derived Cu nanowires at room temperature

This work demonstrates a two-step method to produce oxide-derived Cu nanowires on Cu mesh surface to offer a monolithic catalyst that outstandingly improves the hydrogen production from reforming formaldehyde and water under ambient conditions. Our results not only reveal that the special oxide-derived nanostructure can significantly improve the formaldehyde reforming performance of Cu, but also display that the hydrogen production has a linear relationship with oxygen pressure. Specially, a maximum of 36 times increment in hydrogen generation rate is observed than that without oxygen during the reaction. Density functional theory calculations show that the formaldehyde molecule is adsorbed on Cu surface only when the adsorbed oxygen is in adjacency, and hydrogen release process is the rate-determining step. This work highlights that the activity of deliberately synthesized catalyst can further be promoted by dynamic chemical modulation of surface states during working.

2D/2D heterojunction of cobalt iron selenide and nickel cobalt phosphate for boosted supercapacitor performance

The performance of hybrid supercapacitors is restricted by inferior matched electrochemical kinetics of cathode and anode materials, leading to unsatisfactory energy density and poor cyclic stability. Herein, hierarchically porous cobalt iron selenide (Co0.7Fe0.3Se2) @ nickel cobalt phosphate (NiCoPO) nanosheet arrays are successfully fabricated on carbon cloth substrate via an electrodeposition method, a hydrothermal treatment, followed by an electrodeposition process. The well-designed Co0.7Fe0.3Se2 @NiCoPO cathode material not only combines the merits of high electrical conductivity of Co0.7Fe0.3Se2 and high electrochemical activity of NiCoPO, but also generates interaction and synergistic effect between two constituents. Profiting from its unique core-shell heterostructure with short ion transfer roadways and enhanced conductivity, Co0.7Fe0.3Se2 @NiCoPO electrode yields a specific capacity of 887.4 C g−1 at 1 A g−1, splendid rate capability of 86.2% capacity retention at 20 A g−1, along with a wonderful cycling stability of 91.1% over 5000 cycles. Besides, a Co0.7Fe0.3Se2 @NiCoPO//porous carbon hybrid supercapacitor achieves a maximum energy density of 68.0 Wh kg−1 at 826.6 W kg−1 and outstanding long-term cycling performance with 95.7% initial capacity over 10,000 cycles. Our results propose an efficient approach to construct selenide/phosphate heterojunction with special morphology and nanostructure for advanced energy storage devices.

Formation of subsurface Cu-O-Si system through laser-induced plasma-assisted copper penetration for fabricating robust adhesive copper wire on glass substrate

This study reports an approach, laser-induced plasma-assisted penetration (LIPAP), to facilitate copper diffusion to the glass interior using a femtosecond laser. TEM images and EDS analysis showed copper particles could diffuse into the glass up to 300 nm from the surface. The diffusion was driven by the local high temperatures generated by consecutively incident highly repetitive laser pulses. Furthermore, the HR-TEM images showed that, between the surface copper layer and the internal amorphous SiO2, there were crystalline regions of copper nanoparticles and copper oxides and an amorphous zone, belonging to the Cu-O-Si system, through which, the surface copper layer was firmly connected with the glass substrate. The LIPAPed copper layer then served as a patterning seed for electroless-plating of highly conductive copper wires. Consequently, copper wires with a resistivity of 9.9×10-8Ωm were obtained. Finally, a scratch adhesion test was performed to quantify the adhesion of the resulting copper films. Results showed that copper remained adhered to the surface before reaching the ultimate glass crush load of 30 N, corresponding to normal scratch stress of 240 MPa. Accordingly, based on the LIPAP-formed special subsurface nanostructures serving as the mechanical anchoring basis, highly conductive and adhesive electroless-plated copper wires were achieved.

Study of nano cellulose-based membrane tailorable biodegradability for use in the packaging application of electronic devices

With a growing demand for packaging materials and witnessing many landfills and huge garbage islands floating in the Pacific oceans, the need for an alternative material such as bio-degradable plastics has risen. Cellulose-based materials are already in use in several packaging industries. Nanocellulose, a processed cellulose with a specific nanostructure, have several advantages such as high specific strength, modulus, high surface area and unique optical properties. By varying the crosslinking percentages, the kinetics of degradation can be tailored. In this work, extracted cellulose from sugarcane bagasse was hydrolyzed to obtain nanocellulose, which was used to fabricate packaging films (membrane) with PVA as matrix and nanocellulose. Variations of PVA and nanocellulose loadings, and crosslinking agent ratios. In the fabricated films were investigated for chemical, mechanical, optical, thermal, and topographical properties. Results from the degradation tests under appropriate physically simulated environments have suggested that the crosslinking has enhanced the mechanical properties, extent of degradation was dependent on percentages of crosslinking. A real-world device packaging application was demonstrated by encapsulation of perovskite solar cells with the fabricated nanocellulose film revealed that the lifetime of the devices improved which might be indicative of the film having lower permeability for oxygen and moisture.

Boosting room temperature response of Pd-based hydrogen sensor by constructing in situ nanoparticles

Palladium-based H 2 sensors have attracted increased attention due to the high selectivity for H 2 , yet evident limitations like hydrogen embrittlement and slow response rates, have impeded the further development. Aiming to address these issues, adding other metals to form Pd-based alloys and optimize coincided surface structure, are widely considered as effective approaches. Here in this work, Pd/Ti alloy films with proper elemental ratios were prepared by using a magnetron co-sputtering technique, and the coincided sensing features have been further regulated by in situ nanostructuring. For the Pd/Ti film with an atomic ratio of 74.1/25.9, the H 2 response values characterizations revealed that the limit of detection (LoD) could be 50 ppm at room temperature, combined with a response time of 61.3 s at 2 vt.% H 2 concentration. Based on the first-principles calculations, the effects from hydrogen diffusion process of Pd and Pd/Ti alloys have been evaluated to be ignorable, however, the specific nanostructures constructed on the surface then become the main reason for the boosted response performance. More importantly, the approach of forming proper in situ nanoparticles has been identified as a significant guidance, for extensive and rapid response of H 2 detection of Pd-based sensors used upon low power consumption. • Pd/Ti alloy films with nanoparticles are prepared by magnetron sputtering. • Samples have response to 50 ppm - 4 vt.% H 2 concentration at room temperature. • Nanoparticles can absorb H 2 molecules and facilitate their decomposition into H atoms. • The results of the first-principles calculations confirmed the optimization effect of nanoparticles.

Ingenious Fabrication of Ag-Filled Porous Anodic Alumina Films as Powerful SERS Substrates for Efficient Detection of Biological and Organic Molecules.

Surface-enhanced Raman scattering (SERS) has been widely used to effectively detect various biological and organic molecules. This detection method needs analytes adsorbed onto a specific metal nanostructure, e.g., Ag-nanoparticles. A substrate containing such a structure (called SERS substrate) is user-friendly for people implementing the adsorption and subsequent SERS detection. Here, we report on powerful SERS substrates based on efficient fabrication of Ag-filled anodic aluminum oxide (AAO) films. The films contain many nanopores with small as-grown inter-pore gap of 15 nm. The substrates are created by electrochemically depositing silver into nanopores without an additional pore widening process, which is usually needed for conventional two-step AAO fabrication. The created substrates contain well-separated Ag-nanoparticles with quite a small inter-particle gap and a high number density (2.5 × 1010 cm−2). We use one-step anodization together with omitting additional pore widening to improve the throughput of substrate fabrication. Such substrates provide a low concentration detection limit of 10−11 M and high SERS enhancement factor of 1 × 106 for rhodamine 6G (R6G). The effective detection of biological and organic molecules by the substrate is demonstrated with analytes of adenine, glucose, R6G, eosin Y, and methylene blue. These results allow us to take one step further toward the successful commercialization of AAO-based SERS substrates.

The role of MnO2 crystal morphological scale and crystal structure in selective catalytic degradation of azo dye.

MnO2, as a representative manganese-based catalyst with many kinds of crystal forms, has been widely used to activate PMS. However, the role of morphological scale and crystal structures on the catalytic capability of MnO2 still lacks further study. In this study, four different crystal forms of MnO2 (α-MnO2, β-MnO2, γ-MnO2, and δ-MnO2) are succeeded in being fabricated via hydrothermal processes and evaluated by activating PMS for the removal of Reactive Yellow X-RG, typical azo dye. Experiment results indicate that α-MnO2 with a one-dimensional structure exhibits the best catalytic performance among the four as-prepared MnO2, which can be attributed to its broadest crystal interplanar distance (0.692), the highest portion of Mn (III)/Mn (IV) (4.194), and lowest value of average oxidation state AOS (2.696). Correlation analysis confirms that interplanar distance is the most relative factor with the catalytic activity of MnO2 among the three studied factors (R2 = 0.99715). Meanwhile, the morphological scale structure of α-MnO2 can also account for its highest catalytic ability among the four as-prepared MnO2, including its large specific area and advantageous one-dimensional nanostructure. Furthermore, according to the response surface methodology, when the dosage of PMS is 2.369g/L, the dosage of α-MnO2 is 0.991g/L, and the initial dye concentration is 1025mg/L, the maximum removal rate of Reactive Yellow X-RG is up to 97.38%.