Multiplex templating process in one-dimensional nanoscale: controllable synthesis, macroscopic assemblies, and applications

Bioelectrocatalytic Activity of One-Dimensional Porous Pt Nanoribbons for Efficient Inhibition of Tumor Growth and Metastasis

Designing and synthesizing one-dimensional porous Pt nanocrystals with unique optical, electrocatalytic, and theranostic properties are gaining lots of attention, especially to overcome the challenges of tumor recurrence and resistance to platinum-based chemotherapy. Herein, we represented an interesting report of a one-step and facile strategy for synthesizing multifunctional one-dimensional (1D) porous Pt nanoribbons (PtNRBs) with highly efficient therapeutic effects on cancer cells based on inherent electrocatalytic activity. The critical point in the formation of luminescent porous PtNRBs was the use of human hemoglobin (Hb) as a shape-regulating, stabilizing, and reducing agent with facet-specific domains on which fluorescent platinum nanoclusters at first are aggregated by aggregation-induced emission phenomena (AIE) and then crystallized into contact and penetration twins, as intermediate products, followed by shaping of the final luminescent porous ribbon nanomaterials, owing to oriented attachment association via the Ostwald ripening mechanism. From a medical point of view, the key strategy for effective cancer therapy occured via using low-dosage ethanol in the presence of electroactive porous PtNRBs based on intracellular ethanol oxidation-mediated reactive oxygen species (ROS) generation. The role of heme groups of Hb, as electrocatalytically active centers, was successfully demonstrated in both kinetically controlled anisotropic growth of NRBs for slowing down the reduction of Pt(II) followed by oligomerization of Pt(II)-Hb complexes via platinophilic interactions as well as electrocatalytic ethanol oxidation for therapy. Interestingly, hyaluronic acid-targeted (HA) Hb-PtNRB in the presence of low-dose ethanol caused extraordinary arrest of tumor growth and metastasis with no recurrence even after the treatment course stopped, which caused elongation of tumor-bearing mice survival. HA/Hb-PtNRB was completely biocompatible and exhibited high tumor-targeting efficacy for fluorescent imaging of breast tumors. Therefore, the synergistic electrocatalytic activity of PtNRBs is presented as an efficient and safe cancer theranostic method for the first time.

A comprehensive review on the biomedical frontiers of nanowire applications

This comprehensive review examines the immense capacity of nanowires, nanostructures characterized by unbounded dimensions, to profoundly transform the field of biomedicine. Nanowires, which are created by combining several materials using techniques such as electrospinning and vapor deposition, possess distinct mechanical, optical, and electrical properties. As a result, they are well-suited for use in nanoscale electronic devices, drug delivery systems, chemical sensors, and other applications. The utilization of techniques such as the vapor-liquid-solid (VLS) approach and template-assisted approaches enables the achievement of precision in synthesis. This precision allows for the customization of characteristics, which in turn enables the capability of intracellular sensing and accurate drug administration. Nanowires exhibit potential in biomedical imaging, neural interfacing, and tissue engineering, despite obstacles related to biocompatibility and scalable manufacturing. They possess multifunctional capabilities that have the potential to greatly influence the intersection of nanotechnology and healthcare. Surmounting present obstacles has the potential to unleash the complete capabilities of nanowires, leading to significant improvements in diagnostics, biosensing, regenerative medicine, and next-generation point-of-care medicines.

Necklace-like Te-Au reticula platform with three dimensional hotspots Surface-Enhanced Raman Scattering (SERS) sensor for food hazards analysis

In this work, we combined three-dimensional (3D) necklace-like Te-Au reticula as novel surface-enhanced Raman scattering (SERS) active substrates with oxidation-reduction displacement reactions to construct a molecular machine for SERS detection. The structurally tunable 3D necklace-like spatial structures generated more active 'hot spots' and thus enhanced the sensitivity of SERS signals. Besides, layers of ultrathin nanowires showed high sequence dependence that ensure the repeatability and abundant hotspots at interparticle gaps and guarantee the high SERS performance of the substrate. A better-localized surface plasmon resonance (LSPR) effect of the sensor was verified by finite-difference time-domain (FDTD) analysis in both Raman intensities and electromagnetic field distributions compared to the citrate-stabilized AuNPs and CTAB-protected AuNRs. The proposed strategy can also serve as a universally amplified and sensitive detection platform for monitoring different molecules, thus achieving an amplification detection of 3,3'-diethylthiatricarbocyanine iodide (DTTCI) are 1 nM and R6G with a low limit of detection of 1 pM. Especially, the intensity of the main vibration of R6G from 30 spots of SERS data with excellent reproducibility (relative standard deviation of 6.25 %). High selectivity and accuracy of the SERS sensor were proved by practical analysis melamine (MM) in milk with a linear calibration curve (R2 = 0.9962) and a limit of detection of 0.75 mg/kg. Our research provides a new perspective to construct 3D SERS sensor from integrated structural design.

Natural silk nanofibers as building blocks for biomimetic aerogel scaffolds

Protein nanofibers offer great promise for tissue engineering scaffolds owing to biomimetic architecture and exceptional biocompatibility. Natural silk nanofibrils (SNFs) are promising but unexplored protein nanofibers for biomedical applications. In this study, the SNF-assembled aerogel scaffolds with ECM-mimicking architecture and ultra-high porosity are developed based on a polysaccharides-assisted strategy. The SNFs exfoliated from silkworm silks can be utilized as building blocks to construct 3D nanofibrous scaffolds with tunable densities and desirable shapes on a large scale. We demonstrate that the natural polysaccharides can regulate SNF assembly through multiple binding modes, endowing the scaffolds with structural stability in water and tunable mechanical properties. As a proof of concept, the biocompatibility and biofunctionality of the chitosan-assembled SNF aerogels were investigated. The nanofibrous aerogels have excellent biocompatibility, and their biomimetic structure, ultra-high porosity, and large specific surface area endow the scaffolds with enhanced cell viability to mesenchymal stem cells. The nanofibrous aerogels were further functionalized by SNF-mediated biomineralization, demonstrating their potential as a bone-mimicking scaffold. Our results show the potential of natural nanostructured silks in the field of biomaterials and provide a feasible strategy to construct protein nanofiber scaffolds.

Recent advances in determination applications of emerging films based on nanomaterials

Sensitive and facile detection of analytes is crucial in various fields such as agriculture production, food safety, clinical diagnosis and therapy, and environmental monitoring. However, the synergy of complicated sample pretreatment and detection is an urgent challenge. By integrating the inherent porosity, processability and flexibility of films and the diversified merits of nanomaterials, nanomaterial-based films have evolved as preferred candidates to meet the above challenge. Recent years have witnessed the flourishment of films-based detection technologies due to their unique porous structures and integrated physical/chemical merits, which favors the separation/collection and detection of analytes in a rapid, efficient and facile way. In particular, films based on nanomaterials consisting of 0D metal-organic framework particles, 1D nanofibers and carbon nanotubes, and 2D graphene and analogs have drawn increasing attention due to incorporating new properties from nanomaterials. This paper summarizes the progress of the fabrication of emerging films based on nanomaterials and their detection applications in recent five years, focusing on typical electrochemical and optical methods. Some new interesting applications, such as point-of-care testing, wearable devices and detection chips, are proposed and emphasized. This review will provide insights into the integration and processability of films based on nanomaterials, thus stimulate further contributions towards films based on nanomaterials for high-performance analytical-chemistry-related applications.

A modified flower pollen-based photothermocatalytic process for enhanced solar water disinfection: Photoelectric effect and bactericidal mechanisms

Solar disinfection (SODIS) is regarded as an affordable and effective point-of-use (POU) water disinfection treatment urgently needed in rural developing world. This work developed an enhanced SODIS scheme that utilized a novel flower pollen-based catalyst (Te-TRP). The bench-scale experiments demonstrated 100% photothermocatalytic inactivation of approximately 7-log E. coli K-12, Spingopyxis sp. BM1-1, or S. aureus bacterium by Te-TRP within 40-60 min. Moving toward practical device design, we constructed a flow-through reactor and demonstrated the outstanding water disinfection performance of Te-TRP. The in-depth mechanistic study revealed the synergetic effect between photocatalysis and photothermal conversion and identified the bacterial inactivation pathway. ¹O₂ and ·O₂^¯ were verified to be the dominant reactive oxygen species involved in the bacterial inactivation. The damage to bacterial cells caused by photothermocatalytic reactions was systematically investigated, demonstrating the cell membrane destruction, the loss of enzyme activity, the increased cell membrane permeability, and the complete inactivation of bacteria without the viable but nonculturable state cells. This work not only affords a facile approach to preparing biomaterial-based catalysts capable of efficient photothermocatalytic bacterial inactivation, but also proposes a prototype of POU water treatment, opening up an avenue for sustainable environmental remediation.

Single Atom Sites Catalysts based on High Specific Surface Area Supports

Catalysis is the heart of modern chemical industry. Supports with high specific surface area are crucial for the fabrication of efficient catalysts with elevated metal dispersion. Single atom sites catalysts...

Necklace-like ultrathin silver telluride nanowire films and their reversible structural phase transition

Ultrathin necklace-like Ag2Te nanowires with a diameter of 10 nm and a length of several micrometers are fabricated by a simple solution-based process at low temperature, and the Ag2Te nanowire films are fabricated by a Langmuir-Blodgett technique. A reversible structural phase transition of the nanowire films obtained can be observed, and in addition is also reflected by the electrical properties.

Net-stacked hierarchical CdOHF architectures: controllable synthesis and visible-light driven photocatalytic performance

Net-stacked hierarchical CdOHF architectures were controllably synthesized, and exhibited high efficiency and selectivity for degrading the cationic dye malachite green (MG) under visible light irradiation.

Topochemical synthesis of low-dimensional nanomaterials

Over the past several decades, nanomaterials have been extensively studied owing to having a series of unique physical and chemical properties that exceed those of conventional bulk materials. Researchers have developed a lot of strategies for the synthesis of low-dimensional nanomaterials. Among them, topochemical synthesis has attracted increasing attention because it can provide more new nanomaterials by improving and upgrading inexpensive and accessible nanomaterials. In this review, we summarize and analyze many existing topochemical synthesis methods, including selective etching, liquid phase reactions, high-temperature atmosphere reactions, electrochemically assisted methods, etc. The future direction of topochemical synthesis is also proposed.

The effect of functionalization on solubility and plasmonic features of gold nanoparticles

Effect of functionalization on stability, solubility, and plasmonic features of gold nanoparticle with the general formula of Au₁₈(SR)₁₄ in water solvent has been studied in this work. Thiol functional groups including 1,1-mercapto-ethyl alcohol, s-cysteamine, thioglycolic acid, and beta-mercaptoethanol have been used. Electronic band-gap, excitation energies, dipole moment, and hardness for all gold nanoparticles in water solvent were investigated using the quantum mechanical approach. Intermolecular forces, radial distribution function (RDF), mean square displacement (MSD), and solvation free energy were calculated by using simulation methods. Electronic band-gap, and excitation energy analysis show that surface modification of gold nanoparticles can change their electronic and plasmonic properties. The analysis of dipole moments indicates that ligands affect the nanoparticle's solubility. An increase of hardness and therefore chemical stability can be observed for functionalized nanoparticles compared to the bare structure. Intermolecular energies analyses suggest that structure with 1,1-mercapto ethyl alcohol ligand has the strongest interaction with the solvent. The analysis of RDF diagrams also indicates that the molecule with 1,1-mercapto ethyl alcohol ligand has the sharpest pick. The slope of the linear part of MSD diagrams that is the criterion of solute's lateral diffusion is the highest value for nanoparticle with 1,1-mercapto ethyl alcohol ligand. Furthermore, functionalization also affects solvation free energy contributions. According to obtained data of quantum mechanical calculations and molecular dynamics simulations, it may be concluded that particle with 1,1-mercapto ethyl alcohol is the best ligand for increasing solubility, stability, and plasmonic functions of Au₁₈(SR)₁₄ structures among the examined ones.

Adjustable Ternary FeCoNi Nanohybrids for Enhanced Oxygen Evolution Reaction

Water splitting as a greatly desired technology to produce clean renewable energy, but is hampered by the sluggish oxygen evolution reaction. So, the development of highly active and durable water oxidation electrocatalysts is of primarily significance for energy conversion. Here, a facial strategy to synthesize FeCoNi nanohybrids with adjustable morphological structures by using fluorine is introduced. The morphology and electrocatalytic activity of the sample is determined by the innovative introduction of fluorine. Among them, the overpotential at 10 mA cm^-2 of the best sample is approximately 97 mV lower than the commercial RuO₂ toward the oxygen evolution reaction in 1 m KOH. Additionally, the catalysts also have low Tafel slopes and remarkable stability.

Nanowire Genome: A Magic Toolbox for 1D Nanostructures

1D nanomaterials with high aspect ratio, i.e., nanowires and nanotubes, have inspired considerable research interest thanks to the fact that exotic physical and chemical properties emerge as their diameters approach or fall into certain length scales, such as the wavelength of light, the mean free path of phonons, the exciton Bohr radius, the critical size of magnetic domains, and the exciton diffusion length. On the basis of their components, aspect ratio, and properties, there may be imperceptible connections among hundreds of nanowires prepared by different strategies. Inspired by the heredity system in life, a new concept termed the "nanowire genome" is introduced here to clarify the relationships between hundreds of nanowires reported previously. As such, this approach will not only improve the tools incorporating the prior nanowires but also help to precisely synthesize new nanowires and even assist in the prediction on the properties of nanowires. Although the road from start-ups to maturity is long and fraught with challenges, the genetical syntheses of more than 200 kinds of nanostructures stemming from three mother nanowires (Te, Ag, and Cu) are summarized here to demonstrate the nanowire genome as a versatile toolbox. A summary and outlook on future challenges in this field are also presented.

Recent Advances on Controlled Synthesis and Engineering of Hollow Alloyed Nanotubes for Electrocatalysis

The past decade has witnessed great progress in the synthesis and electrocatalytic applications of 1D hollow alloy nanotubes with controllable compositions and fine structures. Hollow nanotubes have been explored as promising electrocatalysts in the fuel cell reactions due to their well-controlled surface structure, size, porosity, and compositions. In addition, owing to the self-supporting ability of 1D structure, hollow nanotubes are capable of avoiding catalyst aggregation and carbon corrosion during the catalytic process, which are two other issues for the widely investigated carbon-supported nanoparticle catalysts. It is currently a great challenge to achieve high activity and stability at a relatively low cost to realize commercialization of these catalysts. An overview of the structural and compositional properties of 1D hollow alloy nanotubes, which provide a large number of accessible active sites, void spaces for electrolytes/reactants impregnation, and structural stability for suppressing aggregation, is presented. The latest advances on several strategies such as hard template and self-templating methods for controllable synthesis of hollow alloyed nanotubes with controllable structures and compositions are then summarized. Benefiting from the advantages of the unique properties and facile synthesis approaches, the capability of 1D hollow nanotubes is then highlighted by discussing examples of their applications in fuel-cell-related electrocatalysis. Finally, the remaining challenges and potential solutions in the field are summarized to provide some useful clues for the future development of 1D hollow alloy nanotube materials.

Nanowire Electronics: From Nanoscale to Macroscale

Semiconductor nanowires have attracted extensive interest as one of the best-defined classes of nanoscale building blocks for the bottom-up assembly of functional electronic and optoelectronic devices over the past two decades. The article provides a comprehensive review of the continuing efforts in exploring semiconductor nanowires for the assembly of functional nanoscale electronics and macroelectronics. Specifically, we start with a brief overview of the synthetic control of various semiconductor nanowires and nanowire heterostructures with precisely controlled physical dimension, chemical composition, heterostructure interface, and electronic properties to define the material foundation for nanowire electronics. We then summarize a series of assembly strategies developed for creating well-ordered nanowire arrays with controlled spatial position, orientation, and density, which are essential for constructing increasingly complex electronic devices and circuits from synthetic semiconductor nanowires. Next, we review the fundamental electronic properties and various single nanowire transistor concepts. Combining the designable electronic properties and controllable assembly approaches, we then discuss a series of nanoscale devices and integrated circuits assembled from nanowire building blocks, as well as a unique design of solution-processable nanowire thin-film transistors for high-performance large-area flexible electronics. Last, we conclude with a brief perspective on the standing challenges and future opportunities.

Structural Engineering of Low-Dimensional Metal-Organic Frameworks: Synthesis, Properties, and Applications

Low-dimensional metal-organic frameworks (LD MOFs) have attracted increasing attention in recent years, which successfully combine the unique properties of MOFs, e.g., large surface area, tailorable structure, and uniform cavity, with the distinctive physical and chemical properties of LD nanomaterials, e.g., high aspect ratio, abundant accessible active sites, and flexibility. Significant progress has been made in the morphological and structural regulation of LD MOFs in recent years. It is still of great significance to further explore the synthetic principles and dimensional-dependent properties of LD MOFs. In this review, recent progress in the synthesis of LD MOF-based materials and their applications are summarized, with an emphasis on the distinctive advantages of LD MOFs over their bulk counterparties. First, the unique physical and chemical properties of LD MOF-based materials are briefly introduced. Synthetic strategies of various LD MOFs, including 1D MOFs, 2D MOFs, and LD MOF-based composites, as well as their derivatives, are then summarized. Furthermore, the potential applications of LD MOF-based materials in catalysis, energy storage, gas adsorption and separation, and sensing are introduced. Finally, challenges and opportunities of this fascinating research field are proposed.

Emerging Carbon-Nanofiber Aerogels: Chemosynthesis versus Biosynthesis

Carbon aerogels that are typically prepared using sol-gel chemistry have unique three dimensional networks of interconnected nanometer-sized particles and thus exhibit many fascinating physical properties and great application potentials in widespread fields. To boost the practical applications, it is necessary to develop efficient and low-cost methods to produce high-performance carbon aerogels on a large-scale, preferably in a sustainable way. In 2012, two new classes of aerogels consisting of carbon-nanofiber (CNF) networks were prepared from biomass-derived precursors by chemosynthesis (i.e. template-directed hydrothermal carbonization of carbohydrate) and biosynthesis (i.e. use of bacterial cellulose as precursor), respectively. This Review gives a critical overview of this emerging and rapidly developing field, focusing on the synthetic strategies of the carbon-nanofiber aerogels and their outstanding physical properties. We also discuss the multifunctional application potentials of the two sorts of carbon aerogels and their nanocomposites, and highlight the challenges and future opportunities in this field.

Synthesis and investigations on tellurium myconanoparticles

Tellurium has attracted the attention of many researchers and manufacturers due to its unique properties. Through the current work, six fungal isolates have been screened for their ability to reduce potassium tellurite (K₂TeO₃) into elemental tellurium nanoparticles (TeNPs). The most promising fungal isolate was identified as Aspergillus welwitschiae and given the accession number (KY766958) based on molecular basis and has been used for biogenic (enzymatic) production of TeNPs. The produced TeNPs have been characterized using DLS, TEM and FTIR. Data showed that, the particle size is 60.80 d.nm with oval to spherical shape. The produced TeNPs have been evaluated for antimicrobial activity at 25 mg/ml. Data revealed antibacterial activity against E. coli and Staphylococcus aureus (MRSA). Evaluation of the effect of γ-irradiation on TeNPs production showed that, the productivity was improved at 1 kGy and suppressed gradually at higher doses.

Emerging tellurium nanostructures: controllable synthesis and their applications

Tellurium (Te) is a rare element in trace amounts of about one part per billion, comparable to that of platinum and ranked 75th in the abundance of the elements in the earth crust. Te nanostructures, as narrow bandgap semiconductors, have numerous potential applications in the fabrication of many modern devices. The past decades have witnessed an explosion in new strategies for synthesizing diverse emerging Te nanostructures with controlled compositions, sizes, shapes, and structures. Their structure-determined nature makes functional Te nanomaterials an attractive candidate for modern applications. This review focuses on the synthesis and morphology control of emerging Te nanostructures and summarizes the latest developments in the applications of Te nanostructures, such as their use as chemical transformation templates to access a huge family of nanowires/nanotubes, batteries, photodetectors, ion detection and removal, element doping, piezoelectric energy harvesting, gas sensing, thermoelectric devices and many other device applications. Various Te nanostructures with different shapes and structures will exploit the beneficial properties associated with their assembly process and nanofabrication. Finally, the prospects for future applications of Te nanomaterials are summarized and highlighted.

Low Cost Metal Carbide Nanocrystals as Binding and Electrocatalytic Sites for High Performance Li-S Batteries

Lithium sulfur (Li-S) batteries are considered as promising energy storage systems for the next generation of batteries due to their high theoretical energy densities and low cost. Much effort has been made to improve the practical energy densities and cycling stability of Li-S batteries via diverse designs of materials nanostructure. However, achieving simultaneously good rate capabilities and stable cycling of Li-S batteries is still challenging. Herein, we propose a strategy to utilize a dual effect of metal carbide nanoparticles decorated on carbon nanofibers (MC NPs-CNFs) to realize high rate performance, low hysteresis, and long cycling stability of Li-S batteries in one system. The adsorption experiments of lithium polysulfides (LiPS) to MC NPs and corresponding theoretical calculations demonstrate that LiPS are likely to be adsorbed and diffused on the surface of MC NPs because of their moderate chemical bonding. MC NPs turn out to have also an electrocatalytic role and accelerate electrochemical redox reactions of LiPS, as proven by cyclic voltammetry analysis. The fabricated Li-S batteries based on the W₂C NPs-CNFs hybrid electrodes display not only high specific capacity of 1200 mAh/g at 0.2C but also excellent rate performance and cycling stability, for example, a model setup can be operated at 1C for 500 cycles maintaining a final specific capacity of 605 mAh/g with a degradation rate as low as 0.06%/cycle.

Fabrication of ultralong ceria nanobelts via a coordination polymer precursor method

Ultralong cerium-based coordination polymer (CP) nanobelts have been successfully synthesized through a facile solvothemal approach. After calcination in air and being loaded 1 wt% Pt, the catalyst showed satisfactory activity of catalytic reduction of p-nitrophenol.

HMTA-assisted formation of hierarchical Co-based materials built by low-dimensional substructures as water oxidation electrocatalysts

We report a 3D Co-based micro-flower constructed from 2D nanosheets, which exhibits excellent OER performance.

Chitin Liquid-Crystal-Templated Oxide Semiconductor Aerogels

Chitin nanocrystals have been used as a liquid crystalline template to fabricate layered oxide semiconductor aerogels. Anisotropic chitin liquid crystals are transformed to sponge-like aerogels by hydrothermally cross-linked gelation and lyophilization-induced solidification. The hydrothermal gelation of chitin aqueous suspensions then proceeds with peroxotitanate to form hydrogel composites that recover to form aerogels after freeze-drying. The homogeneous peroxotitanate/chitin composites are calcined to generate freestanding titania aerogels that exhibit the nanostructural integrity of layered chitin template. Our extended investigations show that coassembling chitin nanocrystals with other metal-based precursors also yielded semiconductor aerogels of perovskite BaTiO₃ and CuO_x nanocrystals. The potential of these materials is great to investigate these chitin sponges for biomedicine and these semiconductor aerogels for photocatalysis, gas sensing, and other applications. Our results present a new aerogel templating method of highly porous, ultralight materials with chitin liquid crystals.

Facile synthesis of ultrathin Ni-MOF nanobelts for high-efficiency determination of glucose in human serum

Ultrathin Ni-MOF nanobelts, [Ni₂₀(C₅H₆O₄)₂₀(H₂O)₈]·40H₂O(Ni-MIL-77 NBs), were synthesized by a facile one-pot solution process and can be used as an efficient catalyst electrode for glucose oxidation under alkaline conditions. Electrochemical measurements demonstrate that the NB/GCE, when used as a non-enzymatic glucose sensor, offers superior analytical performances with a wide linear range (from 1 μM to 500 μM), a low detection limit (0.25 μM, signal-to-noise = 3), and a response sensitivity of 1.542 μA mM^-1 cm^-2. Moreover, it can also be applied for glucose detection in human blood serum with the relative standard deviation (RSD) of 7.41%, showing the high precision of the sensor in measuring real samples.

Hierarchical Co(OH)F Superstructure Built by Low-Dimensional Substructures for Electrocatalytic Water Oxidation

The development of new materials/structures for efficient electrocatalytic water oxidation, which is a key reaction in realizing artificial photosynthesis, is an ongoing challenge. Herein, a Co(OH)F material as a new electrocatalyst for the oxygen evolution reaction (OER) is reported. The as-prepared 3D Co(OH)F microspheres are built by 2D nanoflake building blocks, which are further woven by 1D nanorod foundations. Weaving and building the substructures (1D nanorods and 2D nanoflakes) provides high structural void porosity with sufficient interior space in the resulting 3D material. The hierarchical structure of this Co(OH)F material combines the merits of all material dimensions in heterogeneous catalysis. The anisotropic low-dimensional (1D and 2D) substructures possess the advantages of a high surface-to-volume ratio and fast charge transport. The interconnectivity of the nanorods is also beneficial for charge transport. The high-dimensional (3D) architecture results in sufficient active sites per the projected electrode surface area and is favorable for efficient mass diffusion during catalysis. A low overpotential of 313 mV is required to drive an OER current density of 10 mA cm^-2 on a simple glassy carbon (GC) working electrode in a 1.0 m KOH aqueous solution.

Sub-1 nm Nanowire Based Superlattice Showing High Strength and Low Modulus

Polymers possess special dimension-dependent processing flexibility which is always absent in inorganic materials. Traditional inorganic nanowires own similar dimensions to polymers, but usually lack near-molecular diameters and the related properties. Here we report that inorganic nanowires with sub1 nm diameter and microscale length can be electrospinningly processed into superstructures including smooth fibers and large-area mat by tuning the viscosity and surface tension of the colloidal nanowires solution. These superstructures have shown both flexible texture and excellent mechanical properties (712.5 MPa for tensile strength, 10.3 GPa for elastic modulus) while retaining properties arising from inorganic components.

Phase-Selective Syntheses of Cobalt Telluride Nanofleeces for Efficient Oxygen Evolution Catalysts

Cobalt-based nanomaterials have been intensively explored as promising noble-metal-free oxygen evolution reaction (OER) electrocatalysts. Herein, we report phase-selective syntheses of novel hierarchical CoTe₂ and CoTe nanofleeces for efficient OER catalysts. The CoTe₂ nanofleeces exhibited excellent electrocatalytic activity and stablity for OER in alkaline media. The CoTe₂ catalyst exhibited superior OER activity compared to the CoTe catalyst, which is comparable to the state-of-the-art RuO₂ catalyst. Density functional theory calculations showed that the binding strength and lateral interaction of the reaction intermediates on CoTe₂ and CoTe are essential for determining the overpotential required under different conditions. This study provides valuable insights for the rational design of noble-metal-free OER catalysts with high performance and low cost by use of Co-based chalcogenides.

Porous One-Dimensional Nanomaterials: Design, Fabrication and Applications in Electrochemical Energy Storage

Electrochemical energy storage technology is of critical importance for portable electronics, transportation and large-scale energy storage systems. There is a growing demand for energy storage devices with high energy and high power densities, long-term stability, safety and low cost. To achieve these requirements, novel design structures and high performance electrode materials are needed. Porous 1D nanomaterials which combine the advantages of 1D nanoarchitectures and porous structures have had a significant impact in the field of electrochemical energy storage. This review presents an overview of porous 1D nanostructure research, from the synthesis by bottom-up and top-down approaches with rational and controllable structures, to several important electrochemical energy storage applications including lithium-ion batteries, sodium-ion batteries, lithium-sulfur batteries, lithium-oxygen batteries and supercapacitors. Highlights of porous 1D nanostructures are described throughout the review and directions for future research in the field are discussed at the end.

General solvothermal approach to synthesize telluride nanotubes for thermoelectric applications

One-dimensional tellurides are good candidates for thermoelectric applications, but the fabrication of telluride nanotubes is still challenging.

Highly Flexible and Porous Nanoparticle-Loaded Films for Dye Removal by Graphene Oxide-Fungus Interaction

Highly flexible and porous films with the ability to load various nanoscale adsorbents are of particular importance in the purification field. Herein, we report the sustainable and large-scale fabrication of a porous and flexible hybrid film based on the graphene oxide/hyphae interaction at a relatively low temperature of 130 °C. Under identical conditions, such films cannot be constructed with solely graphene oxide or hyphae. Moreover, through the addition of nanoscale building blocks [e.g., nanoscale poly(m-phenylenediamine) (PmPD) adsorbents] in the interaction process, the nanoparticles can be in situ loaded into the film. According to FTIR and XPS analyses, the film formation mechanisms mainly involve redox and cross-linking reactions between graphene oxide and fungus hyphae. In a proof-of-concept study, a PmPD nanoparticle-loaded hybrid film was used as a superior key component to build a flow-through adsorption device that displayed a promising adsorption performance toward dye pollutants.

Template Synthesis of Noble Metal Nanocrystals with Unusual Crystal Structures and Their Catalytic Applications

Noble metal nanocrystals own high chemical stability, unique plasmonic and distinctive catalytic properties, making them outstanding in many applications. However, their practical applications are limited by their high cost and scarcity on the earth. One promising strategy to solve these problems is to boost their catalytic performance in order to reduce their usage amount. To realize this target, great research efforts have been devoted to the size-, composition-, shape- and/or architecture-controlled syntheses of noble metal nanocrystals during the past two decades. Impressively, recent experimental studies have revealed that the crystal structure of noble metal nanocrystals can also significantly affect their physicochemical properties, such as optical, magnetic, catalytic, mechanical, electrical and electronic properties. Therefore, besides the well-established size, composition, shape, and architecture control, the rise of crystal structure-controlled synthesis of noble metal nanocrystals will open up new opportunities to further improve their functional properties, and thus promote their potential applications in energy conversion, catalysis, biosensing, information storage, surface enhanced Raman scattering, waveguide, near-infrared photothermal therapy, controlled release, bioimaging, biomedicine, and so on. In this Account, we review the recent research progress on the crystal structure control of noble metal nanocrystals with a template synthetic approach and their crystal structure-dependent catalytic properties. We first describe the template synthetic methods, such as epitaxial growth and galvanic replacement reaction methods, in which a presynthesized noble metal nanocrystal with either new or common crystal structure is used as the template to direct the growth of unusual crystal structures of other noble metals. Significantly, the template synthetic strategy described here provides an efficient, simple and straightforward way to synthesize unusual crystal structures of noble metal nanocrystals, which might not be easily synthesized by commonly used chemical synthesis. To be specific, by using the epitaxial growth method, a series of noble metal nanocrystals with unusual crystal structures has been obtained, such as hexagonal close-packed Ag, 4H Ag, Pd, Pt, Ir, Rh, Os, and Ru, and face-centered cubic Ru nanostructures. Meanwhile, the galvanic replacement reaction method offers an efficient way to synthesize noble metal alloy nanocrystals with unusual crystal structures, such as 4H PdAg, PtAg, and PtPdAg nanostructures. We then briefly introduce the stability of noble metal nanocrystals with unusual crystal structures. After that, we demonstrate the catalytic applications of the resultant noble metal nanocrystals with unusual crystal structures toward different chemical reactions like hydrogen evolution reaction, hydrogen oxidation reaction and organic reactions. The relationship between crystal structures of noble metal nanocrystals and their catalytic performances is discussed. Finally, we summarize the whole paper, and address the current challenges and future opportunities for the template synthesis of noble metal nanocrystals with unusual crystal structures. We expect that this Account will promote the crystal structure-controlled synthesis of noble metal nanocrystals, which can provide a new way to further improve their advanced functional properties toward their practical applications.

Sustainable Hydrothermal Carbonization Synthesis of Iron/Nitrogen-Doped Carbon Nanofiber Aerogels as Electrocatalysts for Oxygen Reduction

It is urgent to develop new kinds of low-cost and high-performance nonprecious metal (NPM) catalysts as alternatives to Pt-based catalysts for oxygen reduction reaction (ORR) in fuel cells and metal-air batteries, which have been proved to be efficient to meet the challenge of increase of global energy demand and CO₂ emissions. Here, an economical and sustainable method is developed for the synthesis of Fe, N codoped carbon nanofibers (Fe-N/CNFs) aerogels as efficient NPM catalysts for ORR via a mild template-directed hydrothermal carbonization (HTC) process, where cost-effective biomass-derived d(+)-glucosamine hydrochloride and ferrous gluconate are used as precursors and recyclable ultrathin tellurium nanowires are used as templates. The prepared Fe/N-CNFs catalysts display outstanding ORR activity, i.e., onset potential of 0.88 V and half-wave potential of 0.78 V versus reversible hydrogen electrode in an alkaline medium, which is highly comparable to that of commercial Pt/C (20 wt% Pt) catalyst. Furthermore, the Fe/N-CNFs catalysts exhibit superior long-term stability and better tolerance to the methanol crossover effect than the Pt/C catalyst in both alkaline and acidic electrolytes. This work suggests the great promise of developing new families of NPM ORR catalysts by the economical and sustainable HTC process.

High-Oriented Polypyrrole Nanotubes for Next-Generation Gas Sensor

Highly oriented PPy nanotubes are grown by in situ vapor phase polymerization within a nanoscale template under low temperature. As-fabricated PPy nanotubes are used for gas sensing, where an ultralow detection limit (0.05 ppb) and very fast response are achieved. Such an in situ mass-productive method for synthesizing highly oriented conducting polymers may pave a new step toward next-generation gas sensors.

Understanding the Solvent Molecules Induced Spontaneous Growth of Uncapped Tellurium Nanoparticles

Understanding the thermodynamic behavior and growth kinetics of colloidal nanoparticles (NPs) is essential to synthesize materials with desirable structures and properties. In this paper, we present specific uncapped Te colloidal NPs obtained through laser ablation of Te in various protic or aprotic solvents. At ambient temperature and pressure, the uncapped Te NPs spontaneously exhibited analogous evolution and growth of “nanoparticle-nanochain-agglomerate-microsphere” in different solvents. The distinctive growth kinetics of the formation of nanochains strongly depended on the polarity and dielectric constant of solvent molecules. The growth rate of agglomerates and microspheres was closely related to the zeta potential of the colloidal solution of Te nanochains and the average size of Te agglomerates. Furthermore, the resulting uncapped Te NPs and Te nanochains displayed a prominent size-dependent and structure-inherited chemical reductive ability. These findings provide insights into the growth of active uncapped nanoparticles in various dispersion media. This study also provides an alternative route in designing novel nanostructures of alloys, telluride, and functional composites using Te as a unique reactive precursor.

Coupling Microbial Growth with Nanoparticles: A Universal Strategy To Produce Functional Fungal Hyphae Macrospheres

Macroscale assembly of nanoscale building blocks is an intriguing way to translate the unique characteristics of individual nanoparticles into macroscopic materials. However, the lack of the efficient universal assembly strategy seriously hinders the possibility of macroscale architectures in practical applications. Herein, we develop a general, environment-friendly, and scalable microbial growth method for the construction of macroscopic composite assemblies with excellent mechanical strength by in situ integrating various types of nanoparticles into fungal hyphae (FH) macrospheres. Notably, the size of the FH-based composite spheres and the loading amount of the nanoparticles with different dimensions can be well tuned by controlling the cultivation time and the dosage of nanoparticles, respectively. Interestingly, bifunctional FH-based core-shell macrospheres can also be achieved by programmed assembling two different kinds of nanoparticles in the cultivation process. The produced multifunctional FH-based composite spheres exhibit wide potential applications in magnetic actuation, photothermal therapy, and contaminant adsorption, etc.