Nanostructured Architectures Research Articles

Construction of Ternary Zn0.5Cu0.5Co2O4 Spinel Structure on Nickel Foam: A Comprehensive Theoretical and Experimental Study from Single to Ternary Metal Oxides for High-Energy-Density Asymmetric Supercapacitor Application.

Developing nanostructured multi-transition metal-based spinel architectures represents a strategic approach for boosting the energy density of supercapacitors while preserving high power density. Here, the influence of incorporating Zn and Cu into Co3O4 spinel systems on supercapacitor performance is investigated by synthesizing single (ZnO, CuO, Co3O4), binary (ZnCo2O4, CuCo2O4), and ternary (Zn0.5Cu0.5Co2O4) oxides on nickel foam substrates. Theoretical and experimental analyses highlight that the flower-like structures of Zn0.5Cu0.5Co2O4, comprising nanowires and nanoribbons, effectively reduced transport barriers and enhanced ion adsorption, thereby improving electron/ion reaction kinetics. Oxygen vacancies induced defect states in Zn0.5Cu0.5Co2O4, shifting the d- and p-band center values closer to the Fermi level and enhancing electrochemical performance. The Zn0.5Cu0.5Co2O4 exhibits a specific capacity of 271 mA h g-1 (1776 F g-1) at 1 A g-1 with 97% capacity retention after 5000 charge/discharge cycles. In a Zn0.5Cu0.5Co2O4//activated carbon configuration, the device demonstrates superior energy and power densities of 122.2 Wh kg-1 and 800 W kg-1, respectively, maintaining 91% capacitance after 10000 cycles at 30 A g-1 with high coulombic efficiency. This study presents an effective strategy to enhance ion/charge transfer and adsorption in multi-transition metal spinel architectures, advancing the development of supercapacitor electrodes.

Exploring novel nanostructural architecture of doubly doped ceria (Ce0.85Sr0.075Sm0.075O2-δ) and barium cerate (BaCeO3) as electrolytes for low-temperature solid oxide fuel cells

This study presents the development of a composite electrolyte for use in low-temperature (300–500 °C) Solid oxide Fuel Cells, focusing on a novel nanostructural design. The electrolyte comprises co-doped ceria (Ce0.85Sr0.075Sm0.075O2-δ, DCO) and barium cerate (BaCeO3, BCO), integrated into a unique nanostructural architecture. Initially, the constituent phases of the composite DCO and BCO are synthesized using a soft-chemical route separately, followed by their integration through liquid mixing technique in various compositions (90:10, 80:20, 70:30, 60:40, 50:50) of DCO:BCO in weight ratio. The composite structure is confirmed by X-ray diffraction, and refined the structural data by Rietveld refinement indicating a structural agreement with cubic and fluorite phases of DCO and BCO, respectively. Scanning Electron microscopy (SEM) and Energy Dispersive X-ray Analysis (EDAX) reveal a uniform distribution of two phases with fine size distribution below 50 nm. Transmission Electron microscopy (TEM) images illustrate the core-shell-like integration of the two phases. High-resolution TEM images indicate that the core consists of the DCO phase, while the shell is composed of the BCO phase. The microstructure of sintered pellets exhibits gas-tight densification, with grains dominated by the DCO phase and BCO phase dispersed along grain boundaries. The ionic conductivity of composite systems is extracted from Electrochemical impedance spectroscopy (EIS) studies, showing that DCO-BCO-40 exhibits the highest conductivity 1.132 × 10−3 Scm−1 @400 °C, which is higher than pristine DCO (0.34 × 10−4 Scm−1 @400 °C). Single cells fabricated using DCO-BCO-40 electrolytes deliver a power output of 280 mW cm−2 whereas pristine DCO showed 279 mW @500 °C. This study exhibits the potential of the core-shell-like nanostructural architecture of electrolytes in advancing Low-temperature solid oxide Fuel cell (LT-SOFC) technology and facilitating the transition toward sustainable energy systems.

Phase formation, structure and properties of quaternary MAX phase thin films in the Cr-V-C-Al system: A combinatorial study

Tailoring of individual atomic layers via alloying to synthesize quaternary MAX phases allows for expanding their chemical diversity and fine-tuning of their properties. In this study, Cr-V/C/Al multilayered precursors were deposited via combinatorial magnetron sputtering, creating nanostructured architectures with periodic stacking of nanolayers and varying Cr:V ratios. Their phase transformation and underlying reaction mechanisms during subsequent thermal annealing in argon towards the prospective quaternary solid solution (CrV)n+1AlCn MAX phases formation was systematically studied. Crystallization of (CrV)2AlC starts at approximately 500°C, while growth of higher-ordered (CrV)4AlC3 is observed from 960°C. Notably, intergrowth of (CrV)2AlC and (CrV)4AlC3 structures with coherent interface suggests that (CrV)2AlC acts as template for nucleation of (CrV)4AlC3. Thermal stability and high-temperature oxidation tests found that (CrV)2AlC exhibits higher thermal stability compared to (CrV)4AlC3 and films with Cr72.7V27.3 displayed good oxidation resistance at 1000°C, forming a protective bilayer oxide scale consisting of (Cr,Al)2O3 and Al2O3.

Approaching 1 GPa Ultra‐High Tensile Strength in a Nanostructured Al–Zn–Mg–Cu–Zr–Sc Alloy Prepared by Severe Plastic Deformation

Alloy composition and heat treatment processes have limited possibility to enhance ultra‐high strength of aluminum alloys, which restricts their widespread application in lightweight equipment. Consequently, high‐density dislocations and grain refinement are suggested to strengthen ultra‐high strength aluminum alloys. Herein, a novel nanostructured Al–Zn–Mg–Cu–Zr–Sc (AZMCZS) alloy with homogeneous microstructure is prepared through the synergistic processing of hot extrusion and high‐pressure torsion. Additionally, the microstructures and strengthening mechanisms of the nanostructured Al alloy are analyzed. It is observed that the ultimate tensile strength of the nanostructured Al alloy reaches nearly 1 GPa, and the elongation of the alloy is 1.9%. The nanostructured Al alloy mainly consists of nanoscale grains (≈117.7 nm), high‐density dislocations (2.4 × 1015 m−2), nano‐sized precipitates (the size of 20–51 nm), and solute atom clusters (≈3 nm). The multiple strengthening mechanisms of the nanostructured Al alloy are revealed in terms of grain refinement, dislocations, precipitates, and solute atom clusters. Grain refinement and dislocation strengthening show superior outcomes and are considered to be the predominant strengthening mechanisms. These findings demonstrate that this nanostructural architecture offers a new way to design super‐strength metals and alloys by effectively controlling the processing regime of severe plastic deformation.

Multiscale analysis of hierarchical flax-epoxy biocomposites with nanostructured interphase by xyloglucan and cellulose nanocrystals

Natural biological systems feature hierarchical nanostructured architectures achieving high strength and toughness. In this work, the spontaneous adsorption of xyloglucan (XG) and cellulose nanocrystals (CNC) onto flax fabrics is considered to develop hierarchical interphases with improved interfacial adhesion in epoxy-based biocomposites. A multi-scale analysis is carried out, from the nano & micrometric scale with the characterization of fibre surface topography, work of adhesion and interfacial shear strength (IFSS) between flax fibres and epoxy resin, to the macroscopic scale with the transverse mechanical properties of biocomposites. At the fibre scale, XG and CNC increase the surface roughness of flax fibres, as well as their adhesion to epoxy resin with IFSS improved by 60 %, up to 22.3 MPa. At the composite scale, the treatments have a major influence on the cohesion of flax cell walls and microstructure of the biocomposites. Transverse tensile tests reveal both cohesive and adhesive interfacial failure.

Self-Powered Quasi-Solid-State Photoelectrochemical Photodetectors Based on MXene Paper Modified by ZnO Nanostructured Architecture

Self-Powered Quasi-Solid-State Photoelectrochemical Photodetectors Based on MXene Paper Modified by ZnO Nanostructured Architecture

Nanostructured Materials for Enhanced Performance of Solid Oxide Fuel Cells: A Comprehensive Review

Solid oxide fuel cells (SOFCs) have emerged as promising candidates for efficient and environmentally friendly energy conversion technologies. Their high energy conversion efficiency and fuel flexibility make them particularly attractive for various applications, ranging from stationary power generation to portable electronic devices. Recently, research has focused on utilizing nanostructured materials to enhance the performance of SOFCs. This comprehensive review summarizes the latest advancements in the design, fabrication, and characterization of nanostructured materials integrated in SOFC. The review begins by elucidating the fundamental principles underlying SOFC operation, emphasizing the critical role of electrode materials, electrolytes, and interfacial interactions in overall cell performance, and the importance of nanostructured materials in addressing key challenges. It provides an in-depth analysis of various types of nanostructures, highlighting their roles in improving the electrochemical performance, stability, and durability of SOFCs. Furthermore, this review delves into the fabrication techniques that enable precise control over nanostructure morphology, composition, and architecture. The influence of nanoscale effects on ionic and electronic transport within the electrolyte and electrodes is thoroughly explored, shedding light on the mechanisms behind enhanced performance. By providing a comprehensive overview of the current state of research on nanostructured materials for SOFCs, this review aims to guide researchers, engineers, and policymakers toward the development of high-performance, cost-effective, and sustainable energy conversion systems.

Self-supported Pt nanoparticles-NiFeP nanosheets arrays nanohybrid with hydrophilic surface towards urea electrolysis

Urea-assisted water electrolysis is a clean, sustainable, and energy-saving method towards hydrogen production. However, the development of earth-abundant, stable, and highly active bifunctional catalysts towards urea electrolysis is still a significant technical challenge. Herein, the highly dispersed Pt nanoparticles decorated NiFeP nanosheets arrays on nickel foam (Pt-NiFeP/NF) electrode is rationally designed, which combines the advantages of superhydrophilic interface, ultrathin nanostructure and open three-dimensional (3D) architecture. Consequently, Pt-NiFeP/NF displays a remarkable electroactivity towards both hydrogen evolution reaction (HER) and urea electrooxidation reaction (UEOR), which only needs the overpotential of 32 mV to achieve the current density of 10 mA cm−2 towards HER, and drives a current density of 50 mA cm−2 at 1.38 V towards UEOR. More importantly, the urea electrolysis system assembled with Pt-NiFeP/NF only requires a cell voltage of 1.41 V to achieve a current density of 100 mA cm−2, much lower than the traditional water electrolysis (1.94 V). This work promotes the application of Pt nanoparticles decorated bimetallic phosphides as a bifunctional catalyst towards urea-rich wastewater treatment and green electrochemical hydrogen production.

A new nanostructured γ-Li3PO4/GeO2 composite for all-solid-state Li-ion battery applications.

High-temperature sintering is crucial to achieve good crystallinity and fast-ion conduction in oxide-type solid-electrolytes such as lithium garnets, NASICONs and LISICONs, leading to stiff ceramics which are difficult to integrate in all-solid-state batteries. Developing conventional oxide-based solid-electrolytes in deformable forms that maintain good ion transport properties and allow facile formulation of bulk-type solid-state batteries, hence, remains a challenge. Here, a new γ-Li3PO4/GeO2 composite, that adopts a novel nanostructured architecture and retains deformability after calcination at 500 °C, is successfully synthesized and densified by cold-pressing. Cold-pressed pellets of the new composite showed an ion conductivity that is four orders of magnitude higher than that of the parent γ-Li3PO4 and comparable to those of high-temperature stiff Li3+xP1-xGexO4 ceramics. The γ-Li3PO4/GeO2 composite is stable against high voltages (up to 5 V vs Li+/Li), which suggests a safe use in contact with high-voltage cathodes. The new composite can also be modified to serve as an active anode layer in solid-state cells due to the electrochemical activity of GeO2 at low voltages (<1 V vs. Li+/Li). This study emphasizes the potential of using low-temperature synthesis to develop novel oxide-based nanoarchitectures for all-solid-state battery applications.

Hybrid nano-microstructured and bioinspired conductive hydrogels with tunable multifunctionality

Conductive hydrogels with tunable multifunctionality show great potential in wearable smart devices. In this work, inspired by the nano-structured architecture strategy and natural mussel adhesive mechanism, a conductive hydrogel (AgPMP...

Atomic layer deposition of magnetic thin films: Basic processes, engineering efforts, and road forward

Atomic layer deposition (ALD) is known as a key enabler of the continuous advances in device engineering for microelectronics. For instance, the state-of-the-art transistor technology depends entirely on ALD-grown high-κ materials. Another application branch where ALD could potentially play a similar important role in future is the magnetic thin film devices. Spin-based devices based on high-quality magnetic thin films are anticipated to provide high-efficiency operations with low power consumption. The strict quality demands the magnetic thin films must fulfill in the next-generation applications form the strong bases for the efforts to implement ALD in this application area. In this first comprehensive review on the topic, our aim is to provide an insightful account of the ALD processes so far developed for magnetic materials and to highlight the application-relevant magnetic properties of the thus fabricated thin films. Moreover, we discuss the various innovative engineering efforts made toward different multi-layered and nanostructured composite materials and complex architectures uniquely enabled by the sophisticated self-terminated film-growth mechanism of ALD. The review is finished with a brief outlook toward the future prospects and challenges in the field.

3D Imaging and Quantitative Subsurface Dielectric Constant Measurement Using Peak Force Kelvin Probe Force Microscopy

AbstractNoninvasive and depth‐sensitive measurements of dielectric properties are becoming of great interest in advanced and complex nanostructured architectures. Here, a straightforward parallel approach applicable in peak force Kelvin probe force microscopy for a 3D measurement of dielectric constants at the nanoscale is demonstrated. The proposed approach features a simultaneous measurement of the mechanical, electrical, and depth‐dependent dielectric properties applied to embedded nanostructures. The findings provide initial elements for further development of experimental dielectric nano‐tomography methods for characterizing buried and embedded systems and dielectric interfaces.

Solar absorptivity analysis of nanostructure perovskite solar cell

Perovskite solar cell is a promising alternative to silicon solar cells; it is cheaper and more environmentally friendly to fabricate with comparable power conversion efficiency. This research investigated the enhancement of the solar absorptivity of a planar structure perovskite solar cell by implementing various nanostructures. Four different glass nanostructure architectures, including nanocone, nanopyramid, nanotube, and nanorod placed at the initial top layer of the cell, were simulated using the three-dimensional finite element method. We studied the effects of nanostructure architecture's varying height and domain area on solar absorptivity. The result showed that the tapered shapes had higher solar absorptivity with increased height. The nanocone with a domain area of 300 nm × 300 nm at the tallest height of 200 nm had the most significant solar absorptivity enhancement with 407 W/m2 of integrated irradiance, 3.3% higher compared to the planar structure. In addition, the analysis of integrated irradiance using AM 1.5 G of different nanocone domain areas revealed various local maxima and minima. These findings suggest an alternative design option to increase efficiency without texturing the active perovskite cell layer.

Enhanced photoelectrochemical properties of ordered branched CdTe nanotubes arrays with near-ideal antireflection

Developing high-performance, stable, and cost-effective photoelectrodes for hydrogen production has been a long-standing challenge. A promising approach has been to utilize photoelectrodes in a nanostructured architecture to improve optical absorption and charge collection. In this work we demonstrate the fabrication of highly ordered branched p-type Cadmium Telluride (CdTe) nanotube arrays and test their efficacy for hydrogen production. The branched CdTe nanotube arrays were fabricated using a combination of top down and bottom up approaches. The diameter and branch shape of vertically aligned CdTe nanotubes are controlled to increase the optical absorption due to the increased optical path length and to improve the charge carrier transfer due to the reduced transfer distance in the nanostructures for charge separation. The CdTe nanotubes with long and fine needle-like shaped branches show enhanced photoelectrochemical properties compared to those of broad-branched CdTe nanotubes. The optical absorption and charge transfer characteristics of a photoelectrochemical photoelectrode can be improved using narrow band-gap materials in well-designed nanostructures.

Filtering low‐energy carriers to enhance thermoelectric performance of Cd‐doped SnSe via incorporation of MXene sheets

AbstractSnSe‐based materials have attracted widespread attention in thermoelectrics due to their outstanding thermoelectric performance. However, the pristine and unmodified polycrystalline SnSe reveals poor electrical properties. Doping and constructing nanostructured composite architectures to produce energy filtering effect proved to be an effective method to strengthen thermoelectric performance. In this study, Ti3C2/Sn0.98Cd0.02Se composites are successfully fabricated by the solvothermal method combined with the electrostatic self‐assembly method and spark plasma sintering. The phase interface introduced by incorporating Ti3C2 into Sn0.98Cd0.02Se can effectively filter low‐energy carriers due to its generation of energy barriers, thereby the Seebeck coefficient of x wt% Ti3C2/Sn0.98Cd0.02Se x = (0.05, 0.5, 1) samples is better than that of the pristine Sn0.98Cd0.02Se over the whole temperature range. Meanwhile, high conductivity was also obtained in 1 wt% Ti3C2/Sn0.98Cd0.02Se sample so that the high power factor of 3.31 μWcm−1K−2 was acquired at 773 K. Ultimately, a peak ZT value of 0.41 was obtained at 773 K, compared with pristine Sn0.98Cd0.02Se, and the thermoelectric performance improved by 24%. This study offers an available approach to efficiently enhance the thermoelectric properties of polycrystalline SnSe‐based materials.

Interfaces in Atomic Layer Deposited Films: Opportunities and Challenges

Atomic layer deposition (ALD) is an effective method for precise layer‐wise growth of thin‐film materials and has allowed for substantial progress in a variety of fields. Advances in the technique have instigated high‐level interpretations of the relationship between nanostructure architecture and performance. An inherent part in the ALD of films is the underlying interfaces between each material, which plays a significant role in advanced electronics. Considering the impact of sandwiched substructures, it is appropriate to highlight opportunities and challenges faced by applications that rely on these interfaces. This review encompasses the current prospects and obstacles to further performance improvements in ALD‐generated interfaces. 2D electron gas, high‐k materials, freestanding layered structures, lattice matching, and seed layers, as well as prospects for future research, are explored.

One-Dimensional, First-Row Transition Metal, Core-Shell Architectures as Multifunctional Electrocatalysts in Alkaline and Acidic Conditions

The development of practical electrocatalysts for fuel cells, electrochemical sensors, and batteries requires nanostructured architectures with high catalytic activity and good long-term durability. It is also essential that they have very low or even no platinum content. There has also been a recent emphasis on the importance of designing multifunctional catalysts with the ability to efficiently catalyze a wide-range of electrochemical reactions in both acidic and alkaline media. In light of these requirements, we have developed a solution-based synthetic method to prepare core-shell nanowires consisting of inexpensive and abundant first-row transition metals coated with precious metal shells. The core-shell motif enables a substantial quantity of platinum to be removed from the catalytically inactive core of the material, while also resulting in the ability to tune the activity of platinum through electronic and structural interactions between the two metals. The as-synthesized core-shell nanowires have a complex surface structure that brings together metal oxide and precious metal active sites that are active toward OER and result in a significant reduction in the overpotential for OER when compared with pure Pt and Co nanowires. In addition, we have developed an electrochemical process that selectively removes the metal oxide from the surface of the nanowires enabling the catalysts to be activated toward SOM oxidation in acidic media and ORR in alkaline media. For example, the activated core-shell nanowires display a 1.5-fold and a 4-fold increase in the specific activity and mass activity of methanol oxidation, respectively, relative to a pure platinum nanowire.

Electric Field-Induced Nano-Assembly Formation: First Evidence of Silicon Superclusters with a Giant Permanent Dipole Moment.

The outstanding properties of silicon nanoparticles have been extensively investigated during the last few decades. Experimental evidence and applications of their theoretically predicted permanent electric dipole moment, however, have only been reported for silicon nanoclusters (SiNCs) for a size of about one to two nanometers. Here, we have explored the question of whether suitable plasma conditions could lead to much larger silicon clusters with significantly stronger permanent electric dipole moments. A pulsed plasma approach was used for SiNC production and surface deposition. The absorption spectra of the deposited SiNCs were recorded using enhanced darkfield hyperspectral microscopy and compared to time-dependent DFT calculations. Atomic force microscopy and transmission electron microscopy observations completed our study, showing that one-to-two-nanometer SiNCs can, indeed, be used to assemble much larger "superclusters" with a size of tens of nanometers. These superclusters possess extremely high permanent electric dipole moments that can be exploited to orient and guide these clusters with external electric fields, opening the path to the controlled architecture of silicon nanostructures.

Binder-free Li-O 2battery cathodes using Ni- and PtRu-coated vertically aligned carbon nanofibers as electrocatalysts for enhanced stability

The development of an ideal cathode for Li-O₂ battery (LOB) has been a great challenge in achieving high discharge capacity, enhanced stability, and longevity. The formation of undesired and irreversible discharge products on the surface of current cathode materials limit the life span of the LOB. In this study, we report the systematic electrochemical study to compare the performance of LOB employing a unique graphitic nanostructured carbon architecture, i.e., vertically aligned carbon nanofiber (VACNF) arrays, as the cathode materials. Transition metal (Ni) and noble metal alloy (PtRu) are further deposited on the VACNF array as electrocatalysts to improve the discharge/charge processes at the cathode. The structure of as-prepared electrodes was examined with the field emission scanning electron microscopy, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy (XPS). The LOB with VACNF-Ni electrode delivered the highest specific and areal discharge capacities (14.92 Ah·g⁻¹, 4.32 mAh·cm⁻²) at 0.1 mA·cm⁻² current density as compared with VACNF-PtRu (9.07 Ah·g⁻¹, 2.62 mAh·cm⁻²), bare VACNF (5.55 Ah·g⁻¹, 1.60 mAh·cm⁻²) and commercial Vulcan XC (3.83 Ah·g⁻¹, 1.91 mAh·cm⁻²). Cycling stability tests revealed the superior performance of VACNF-PtRu with 27 cycles as compared with VACNF-Ni (13 cycles), VACNF (8 cycles), and Vulcan XC (3 cycles). The superior cycling stability of VACNF-PtRu can be attributed to its ability to suppress the formation of Li₂CO₃ during the discharge cycle, as elucidated by XPS analysis of discharged samples. We also investigated the impact of carbon cloth and carbon fiber as cathode electrode substrate on the performance of LOB.

Reaction stoichiometry directs the architecture of trimetallic nanostructures produced via galvanic replacement.

Galvanic replacement (GR) of monometallic nanoparticles (NPs) provides a versatile route to interesting bimetallic nanostructures, with examples such as nanoboxes, nanocages, nanoshells, nanorings, and heterodimers reported. The replacement of bimetallic templates by a more noble metal can generate trimetallic nanostructures with different architectures, where the specific structure has been shown to depend on the relative reduction potentials of the participating metals and lattice mismatch between the depositing and template metal phases. Now, the role of reaction stoichiometry is shown to direct the overall architecture of multimetallic nanostructures produced by GR with bimetallic templates. Specifically, the number of initial metal islands deposited on a NP template depends on the reaction stoichiometry. This outcome was established by studying the GR process between intermetallic PdCu (i-PdCu) NPs and either AuCl2- (Au1+) or AuCl4- (Au3+), producing i-PdCu-Au heterostructures. Significantly, multiple Au domains form in the case of GR with AuCl2- while only single Au domains form in the case of AuCl4-. These different NP architectures and their connection to reaction stoichiometry are consistent with Stranski-Krastanov (SK) growth, providing general guidelines on how the conditions of GR processes can be used to achieve multimetallic nanostructures with different defined architectures.