Advanced Nanostructured Materials Research Articles

Efficient steam generation by inexpensive narrow gap evaporation device for solar applications

Technologies for solar steam generation with high performance can help solving critical societal issues such as water desalination or sterilization, especially in developing countries. Very recently, we have witnessed a rapidly growing interest in the scientific community proposing sunlight absorbers for direct conversion of liquid water into steam. While those solutions can possibly be of interest from the perspective of the involved novel materials, in this study we intend to demonstrate that efficient steam generation by solar source is mainly due to a combination of efficient solar absorption, capillary water feeding and narrow gap evaporation process, which can also be achieved through common materials. To this end, we report both numerical and experimental evidence that advanced nano-structured materials are not strictly necessary for performing sunlight driven water-to-vapor conversion at high efficiency (i.e. ≥85%) and relatively low optical concentration (≈10 suns). Coherently with the principles of frugal innovation, those results unveil that solar steam generation for desalination or sterilization purposes may be efficiently obtained by a clever selection and assembly of widespread and inexpensive materials.

Cadmium Chalcogenide Nano-Heteroplatelets: Creating Advanced Nanostructured Materials by Shell Growth, Substitution, and Attachment.

The current direction in the evolution of 2D semiconductor nanocrystals involves the combination of metal and semiconductor components to form new nanoengineered materials called nano-heteroplatelets. This Review covers different heterostructure architectures that can be applied to cadmium chalcogenide nanoplatelets, including variously shaped shell, metal nanoparticle decoration, and doped and alloy systems. Here, for the first time a complete classification of nano-heteroplatelet types is provided with recommended notations and a systematization of the existing knowledge and experience concerning heterostructure formation techniques, addressing the morphology, optoelectronic and magnetic properties, and novel features of different heterostructures. This Review is also devoted to possible applications of these heterostructures and of one-component nanoplatelets in multiple fields, including light-emitting devices and biological imaging.

A green method for production of nanobiochar by ball milling- optimization and characterization

Environmental considerations along with the technological challenges have led to search for green and energy-efficient processes for advanced nanostructured materials. In this study, nanobiochar was produced from pine wood biochar using a planetary ball mill. A central composite experimental design and response surface methodology was employed to optimize the ball milling parameters including time, rotational speed and ball to powder mass ratio to obtain nanoparticles in short time and at lower energy consumption. ANOVA results showed that the linear and quadratic effect estimates of time and the interaction effect of time and rotational speed were significant contributors to the size of particles during milling (p < 0.05). Based on the developed statistical model, the optimum conditions for obtaining the smallest particles, around 60 nm, were found to be 1.6 h, 575 rpm and 4.5 g/g. However, the size measurements indicated that particles had a great tendency to agglomerate. Further study showed that the conditioning of biochar at cryogenic temperatures prior to milling inhibits the agglomeration of nanoparticles which is essential in industrial processes. The adsorption test proved that the nanobiochar produced using green method is promising in the removal of micropollutants from aqueous media by removing up to 95% of carbamazepine from water. At the optimum milling parameters and conditioning for 24 h at −80 °C, nanobiochar with the average size of around 60 nm was obtained. The produced nanobiochar was characterized by Brunauer-Emmett-Teller (BET) gas porosimetry, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Also, physical and chemical properties, such as water holding capacity, organic matter, oxidation-reduction potential (ORP), elemental composition, polycyclic aromatic hydrocarbons (PAHs) and heavy metals were analyzed.

Electromagnetic characterization of advanced nanostructured materials and multilayer design optimization for metrological and low radar observability applications

In this work the electromagnetic characterization of composite materials reinforced with carbon and metallic nanoparticles is presented. In particular, the electric permittivity and the magnetic permeability as a function of the frequency are used to evaluate the electromagnetic absorption capability of the nanocomposites. The aim is the study of possible applications in advanced coating able to tune the electromagnetic reflectivity of satellite surfaces in specific frequency ranges, in a special way for those surfaces that for some reason could be exposed to the antenna radiation pattern. In fact, the interference caused by the spurious electromagnetic multipath due to good electric conductive satellite surface components could in turn affect the main radiation lobe of TLC and Telemetry antennas, thus modifying its main propagation directions and finally increasing the microwave channel pathloss. The work reports the analysis of different nanostructured materials in the 2–10GHz frequency range. The employed nanopowders are of carbon nanotubes, cobalt, argent, titanium, nickel, zinc, copper, iron, boron, bismuth, hafnium, in different weight percentages versus the hosting polymeric matrix. The materials are classified as a function of their electromagnetic losses capability by taking into account of both electric and magnetic properties. The possibility to design multi-layered structures optimized to provide specific microwave response is finally analyzed by the aid of swam intelligence algorithm. This novel technique is in general interesting for metrological purpose and remote sensing purposes, and can be effectively used in aerospace field for frequency selective materials design, in order to reduce the aircraft/spacecraft radar observability at certain frequencies.

Facile Preparation of 3D Nanostructured O/N co-Doped Porous Carbon Constructed by Interconnected Carbon Nanosheets for Excellent-Performance supercapacitors

A facile and readily scalable approach to prepare O/N co-doped 3D nanostructured foam-like porous carbon composed of interconnected carbon nanosheets (NFPCs) has been successfully explored. The NFPCs are synthesized from normal reagents including melamine resin, coal tar pitch, magnesium acetate and KOH, and firstly found that the KOH exerts a vital role in constructing the 3D foam-like nanostructure. The 3D foam-like porous carbon possesses continuous macropores, high surface area, interconnected 8nm thick carbon nanosheets, especially, a good deal of nanosized fissures in carbon nanosheets and high content of oxygen/nitrogen heteroatoms, which endow NFPCs with superior capacitive performance. The NFPC0.4-0.4Y-700 exhibits a high specific capacitance of 302Fg−1 at 5Ag−1 and high rate capability (92% retention from 5 to 50Ag−1) in 6M KOH. The NFPC0.4-0.4Y-700 symmetrical supercapacitor has presented a high energy density of 21 Wh kg−1 at 865Wkg−1 in 1M Na2SO4 electrolyte. The simple, cost-effective and scalable synthesis strategy to produce advanced nanostructured carbon materials from industrialized reagent provides a new protocol for fabricating excellent performance supercapacitors.

Recent Modifications of bentonite Clay for Adsorption Applications

Adsorptive removal of toxic compounds makes practical and effective use of modified bentonite composite is a standout amongst the most appealing methodologies. Lately, the modified bentonite, a subset of advanced porous nanostructured materials, due to their unique characteristics are demonstrating awesome guarantee for better adsorption of different water contaminants. Given the significance of organic and inorganic removal, as a vital class of pollutants, this research article intends to review and summarize, quickly the as of late published research on the adequacy of various modified bentonite adsorbents under different physico-chemical process parameters in organic and inorganic contaminants adsorption. The impact of pH, the adsorption mechanism and the applicability of various adsorption kinetic and thermodynamic models are briefly discussed. The vast majority of the outcomes watched demonstrated that the adsorption kinetic and isotherm mostly followed the pseudo-second order and Langmuir models respectively.

Advanced Particle Characterization Techniques

Advanced Particle Characterization Techniques

Iron-Based Electrocatalysts Supported on Nanostructured Carbon to Enhance Oxygen Reduction in Microbial Fuel Cells

Sustainable waste management and energy supply can find a concrete answer in the technology of microbial fuel cells (MFCs). One of the major barriers to the widespread diffusion of this technology is the high cost of materials, among which the platinum-based cathode accounts for about 50 % of the total cell cost. Although platinum is a highly effective oxygen reducing catalyst, its activity is decreased by a variety of poisoning substances present in wastewater [1]. Latest development on nanostructured carbon for energy storage and conversion has brought to light carbon nanofibers (CNF), carbon nanotubes (CNT) and activated carbon (AC) as good candidates to replace costly Pt. These materials have high surface area and conductivity, and nitrogen doping has been demonstrated to be an effective approach to modulate their electronic properties [2]. Moreover, recent advances on non platinum group metal (NPGM) catalysts demonstrated the possibility to replace Pt with earth-abundant elements, such as Mn, Fe, Co, and Cu [3]. Among all, iron based catalysts supported on carbon have being used at cathodes of MFCs, active sites arising from Fe/N/C coordination. Aim of this study is to evaluate and compare catalytic activity towards oxygen reduction reaction (ORR) of catalysts based on iron phthalocyanine (FePc) supported over different carbon substrates with physical and morphological differences. Commercial carbon black, carbon nanotubes, and black pearls were used as catalyst support. Furthermore, the use of different advanced nanostructured carbon materials, such as carbon nanofibers and carbon xerogels was also investigated, owing to their porous structure and surface properties which can be tailored according to catalytic requirements [4, 5]. To facilitate catalyst dispersion and obtain effective ORR active sites, the supports were modified by a two-step treatment with nitric acid and ammonia gas. The treatment allowed introducing oxygen and nitrogen functionalities on the carbon surface while maintaining an extensively developed porous structure, as demonstrated by elemental analysis, BET, and X-ray photoelectron spectroscopy (XPS). Electrocatalysts derived from iron phthalocyanine (FePc) and the different carbon supports were prepared and their electrochemical activity towards ORR was assessed by cyclic voltammetry and rotating disk voltammetry experiments. The electrochemical results demonstrated that the prepared electrocatalysts are all active towards ORR at neutral pH; the higher the density of pyridinic nitrogen on the sample surface, the greater is the performance, as indicated by XPS. The applicability of FePc-based materials as ORR cathodes of MFCs was evaluated by assemblying FePc cathodes in single chamber air-catodes MFCs operating with sodium acetate in phosphate buffer solution, which coulombic efficiency, polarization and power density curves, and voltage generation cycles over time were acquired. The body of results demonstrated the potential ability of FePc-electrocatalysts to substitute platinum for ORR in MFCs.

(Invited) Impact of Spark Plasma Sintering on the Thermoelectric Properties of Advanced Nanostructured Materials for Waste Heat Recovery

The rapid development of nanomaterials in the past decade has provided a possibility of directly converting waste heat back to electricity based on the thermoelectric Seebeck effect. In the past four years, we have developed a transformative approach to pioneered low cost and scalable solution-phase growth methods to mass produce thermoelectric nanowires and nanowire heterostructures to match the physical and economic magnitudes of energy use and economical entertainment in the manufacture/recycling. We have studied how spark plasma sintering can help to improve the density, mechanical strength, and electrical conductivity of these nanowires and nanowire heterostructures while minimizing the phase impurity and grain growth. These nanostructured thermoelectric materials show a significantly enhanced performance compared to the bulk crystals based on the quantum confinement and energy filtering.

Advanced Nano-Structured Materials for Photocatalytic Water Splitting

The production of oxygen and hydrogen from solar water splitting has been considered to be an ultimate solution for energy and environmental issues, and over the past few years, nano-sized semiconducting metal oxides alone and with graphene have been shown to have great promise for use in photocatalytic water splitting. It is challenging to find ideal materials for photoelectrochemical water splitting, and these have limited commercial applicability due to critical factors, including their physico-chemical properties, the rate of charge-carrier recombination and limited light absorption. This review article discusses these main features, and recent research progress and major factors affect the performance of the water splitting reaction. The mechanism behind these interactions in transition metal oxides and graphene based nano-structured semiconductors upon illumination has been discussed in detail, and such characteristics are relevant to the design of materials with a superior photocatalytic response towards UV and visible light. Keywords: Photocatalyst, graphene nanocomposites, Water splitting, Hydrogen energy storage, Photoelectrochemical cell

Advanced Nano-Structured Materials for Photocatalytic Water Splitting

Advanced Nano-Structured Materials for Photocatalytic Water Splitting

Switchable Materials for Smart Windows.

This article reviews the basic principles of and recent developments in electrochromic, photochromic, and thermochromic materials for applications in smart windows. Compared with current static windows, smart windows can dynamically modulate the transmittance of solar irradiation based on weather conditions and personal preferences, thus simultaneously improving building energy efficiency and indoor human comfort. Although some smart windows are commercially available, their widespread implementation has not yet been realized. Recent advances in nanostructured materials provide new opportunities for next-generation smart window technology owing to their unique structure-property relations. Nanomaterials can provide enhanced coloration efficiency, faster switching kinetics, and longer lifetime. In addition, their compatibility with solution processing enables low-cost and high-throughput fabrication. This review also discusses the importance of dual-band modulation of visible and near-infrared (NIR) light, as nearly 50% of solar energy lies in the NIR region. Some latest results show that solution-processable nanostructured systems can selectively modulate the NIR light without affecting the visible transmittance, thus reducing energy consumption by air conditioning, heating, and artificial lighting.

Binder-free network-enabled MoS2-PPY-rGO ternary electrode for high capacity and excellent stability of lithium storage

A unique MoS2-based composite composed of MoS2 nanosheets wrapped by a conductive polypyrrole (PPY) layer and closely incorporated within reduced graphene oxide (rGO) nanosheets is prepared by all-solution method. As a free-binder electrode for lithium-ion batteries, the ternary electrode delivers an initial discharge capacity of 1428 mAh g−1, maintains 1070 mAh g−1 after 400 cycles at a current density of 200 mA g−1, and also exhibits superior rate capacity of 600 mAh g−1 at a high current density of 2000 A g−1. The enhanced electrochemical performance is attributed to the advantageous combination of the 3D hierarchically rGO skeleton and in-situ formed conductive PPY coating. This design route represents a new direction for high-performance lithium ion batteries and related energy storage application with advanced nanostructured materials.

Charge storage in KCu7S4 as redox active material for a flexible all-solid-state supercapacitor

Supercapacitors are promising devices for highly efficient energy storage and power management. A notable improvement in performance has been achieved through recent advances in understanding charge storage mechanism and the development of advanced nanostructured materials. Here, by combining experimental and theoretical investigations, we have unveiled the detailed charge storage mechanism of KCu7S4 wires based on a flexible all-solid-state supercapacitor. KCu7S4 with a unique double-tunnel structure and excellent conductivity exhibits outstanding properties as an electrode material in supercapacitors. Both electrochemical experiments and DFT calculations show that the stable energy storage process is mainly contributed by potassium ions׳ insertion/extraction, where potassium ions are proved to have been more active than lithium ions in the redox reactions on the KCu7S4 electrodes. The flexible supercapacitor based on the KCu7S4/Graphene paper is low-cost, easy to fabricate and environmentally friendly. The understanding for the charge storage presented in this work would guide the improvement on supercapacitor and exploration of new electrode materials.

Modeling the Flow in Nanostructured Sensors within Hybrid Welding Systems

This paper aims to present the recent results in modeling flows behavior in some specific nanostructured sensors. The sensor’s concept is based on the advanced properties of the nanostructured materials. That is because the results in the field of the nanotechnologies showed that the sensors that are using advanced nanostructured materials are smaller, more precise, faster in response, and more efficient. The efficiency of such new type of sensor is claimed by some aspects which appear during the hybrid welding process.

ChemInform Abstract: Nanostructured Metallic Electrocatalysts for Carbon Dioxide Reduction

AbstractReview: [38 refs.

Nanostructured Metallic Electrocatalysts for Carbon Dioxide Reduction

AbstractThe recent development of nanostructured electrocatalysts for CO2 reduction has attracted much attention because they exhibit unique properties compared to their bulk counterparts. In this minireview, the latest studies on electrocatalytic CO2 reduction with a focus on the advances of nanostructured metallic electrocatalysts are reviewed and discussed. The distinct catalytic properties and potential challenges of nanostructured electrocatalysts are summarized. The behavior of nanosized catalysts in ionic liquid electrolytes is also discussed. Ideas for the design of next‐generation electrocatalysts by taking the advantages of nanostructured materials are proposed.

Nanostructured Carbon Materials as Supports in the Preparation of Direct Methanol Fuel Cell Electrocatalysts

Different advanced nanostructured carbon materials, such as carbon nanocoils, carbon nanofibers, graphitized ordered mesoporous carbons and carbon xerogels, presenting interesting features such as high electrical conductivity and extensively developed porous structure were synthesized and used as supports in the preparation of electrocatalysts for direct methanol fuel cells (DMFCs). The main advantage of these supports is that their physical properties and surface chemistry can be tailored to adapt the carbonaceous material to the catalytic requirements. Moreover, all of them present a highly mesoporous structure, diminishing diffusion problems, and both graphitic character and surface area can be conveniently modified. In the present work, the influence of the particular features of each material on the catalytic activity and stability was analyzed. Results have been compared with those obtained for commercial catalysts supported on Vulcan XC-72R, Pt/C and PtRu/C (ETEK). Both a highly ordered graphitic and mesopore-enriched structure of these advanced nanostructured materials resulted in an improved electrochemical performance in comparison to the commercial catalysts assayed, both towards CO and alcohol oxidation.

Three-Dimensional Hierarchical Ternary Nanostructures for High-Performance Li-Ion Battery Anodes

Silicon is considered one of the most promising anode materials for high-performance Li-ion batteries due to its 4200 mAh/g theoretical specific capacity, relative abundance, low cost, and environmental benignity. However, silicon experiences a dramatic volume change (∼300%) during full charge/discharge cycling, leading to severe capacity decay and poor cycling stability. Here, we report a three-dimensional (3D) ternary silicon nanoparticles/conducting polymer/carbon nanotubes hybrid anode material for Li-ion batteries. The hierarchical conductive hydrogel framework with carbon nanotubes as the electronic fortifier offers a continuous electron transport network and high porosity to accommodate the volume expansion of Si particles. By 3D wrapping of silicon nanoparticles/single-wall carbon nanotubes with conducting polymer nanostructures, a greatly improved cycling performance is achieved with reversible discharge capacity over 1600 mAh/g and 86% capacity retention over 1000 cycles at the current rate of 3.3 A/g. Our findings represent a new direction for fabricating robust, high-performance lithium-ion batteries and related energy storage applications with advanced nanostructured materials.

Determination of atomistic J-integral of graphene sheet using the molecular dynamics method

Over the past decade, mechanical characterization data for nanoparticle-reinforced polymer matrix composites have shown significant improvements in compressive strength and interlaminar shear strength, in comparison with baseline properties. While the synergistic reinforcing influence of nanoparticle reinforcement is obvious, a simple rule-of-mixtures approach fails to quantify the dramatic increase in mechanical properties. Consequently, there is an immediate need to investigate and understand the mechanisms at the nanoscale that are responsible for such unprecedented strength enhancements. A multi-scale and multi-physics simulation approach is considered computationally more viable since relying on a single time or length scale may require huge amounts of computational resources and can potentially lead to inaccurate results. A proof-of-concept case study involving crack initiation in a graphene nanoplatelet is presented, together with a methodology for computing the atomistic J-integral based on Hardy estimates of continuum fields. The same methodology will be used to gain a better understanding of the influence of nanoscale phenomena on continuum-scale mechanical properties of a polymer nanocomposite. It is envisioned that the current research will contribute towards the understanding of advanced nanostructured composite materials within the context of integrated computational materials engineering.