Nanostructured Materials Research Articles

Challenges and Opportunities for 2D Materials in Energy Storage Technologies

Efficient energy storage systems represent a critical technology across many sectors including consumer electronics, electrified transportation, and a smart grid accommodating intermittent renewable energy sources. Arguably, the most important advance in energy storage over the past three decades is the lithium-ion battery, which was recognized with the Nobel Prize in Chemistry. However, despite its many successes, issues related to safety, energy density, charging time, and operating temperature range have hindered the realization of the full potential of lithium-ion battery technology, particularly in large-scale applications such as grid-level storage and full electrification of transportation networks. Nanostructured materials were once thought to present compelling opportunities for next-generation lithium-ion batteries, but inherent problems related to high surface area to volume ratios at the nanometer-scale (e.g., undesirable surface chemical interactions between electrodes and electrolytes) have impeded their adoption for commercial applications. This talk will explore how chemically inert two-dimensional (2D) materials are driving a resurgence in nanostructured lithium-ion battery materials [1,2]. For example, conformal graphene coatings on battery anode and cathode powders mitigate surface degradation and minimize the formation of the solid electrolyte interphase, thus improving cycling stability [3,4]. In addition, the high electrical conductivity of graphene reduces cell impedance, resulting in enhanced kinetics that enable high-rate capability and low-temperature performance down to –20 °C [5]. On the other hand, ionogel electrolytes based on ionic liquids and hexagonal boron nitride (hBN) nanoplatelets provide safe, high-rate operation at high temperatures up to 175 °C, which represents the highest operating temperature to date for solid-state lithium-ion batteries [6,7]. The strong interfacial interactions between hBN and ionic liquids further enable novel electrolyte architectures based on layered heterostructure ionogels that result in unprecedently high energy densities and rate performance for solid-state batteries [8]. Since hBN ionogels can be formulated into printable inks and slurries, these electrolytes also present promising opportunities for additive manufacturing of solid-state batteries, supercapacitors, and related energy storage technologies [9-11].[1] D. Lam, et al., ACS Nano, 16, 7144 (2022).[2] N. S. Luu, et al., Accounts of Materials Research, 3, 511 (2022).[3] J.-M. Lim, et al., Matter, 3, 522 (2020).[4] K.-Y. Park, et al., Advanced Energy Materials, 10, 2001216 (2020).[5] K.-Y. Park, et al., Advanced Materials, 34, 2106402 (2022).[6] W. J. Hyun, et al., ACS Nano, 13, 9664 (2019).[7] W. J. Hyun, et al., Advanced Energy Materials, 10, 2002135 (2020).[8] W. J. Hyun, et al., Advanced Materials, 33, 2007864 (2021).[9] C. M. Thomas, et al., ACS Energy Letters, 7, 1558 (2022).[10] W. J. Hyun, et al., Nano Letters, 22, 5372 (2022).[11] L. E. Chaney, et al., Advanced Materials, DOI: 10.1002/adma.202305161 (2023).

Composite Ion-Exchange Membranes with High Specific Ion Selectivity for Efficient Electro-Membrane Processes

The advancement of ion-exchange membranes (IEMs) with heightened permselectivity for specific ions is pivotal for improving electro-membrane processes. Achieving targeted ion selectivity necessitates precise control over membrane surface characteristics, including electrostatic forces, ion transport channel size, and hydrophobicity. Utilization of diverse nanostructured materials, particularly metal-organic frameworks (MOFs), offers a pathway to modify these surface properties. MOFs, known for their structural diversity, adjustable pore sizes, and customizable frameworks, are widely applied in separation, catalysis, electrochemical, and biomedical fields. This study presents novel composite membranes, enhanced with various nanostructured materials including MOFs, demonstrating improved specific ion selectivity, robust physical strength, and superior electrochemical properties compared to standard commercial membranes. Notably, these membranes exhibit augmented performance in water-splitting electrodialysis for LiOH production, attributed to enhanced proton-blocking and monovalent ion permeability. This work was supported by the National Research Foundation of Korea (NRF) grants funded by the Korea government (MEST) (NRF-2022M3C1A3081178 and NRF-2022M3H4A4097521).

(Invited) Design of Photoactive Inorganic Nanomaterials for Environmental Challenges

Nowadays, one of the main technological challenges that we are facing is the ability to provide a sustainable supply of clean energy and, among all renewable sources, solar energy displays the greatest potential. Recently, the development of novel synthetic strategies has led to the preparation of nanostructured materials displaying unique properties compared to the bulk counterpart systems, with controlled and tunable morphologies able to enhance the activity and selectivity of a catalytic process. In particular, nanostructured materials synthesized via the bottom–up approach present an opportunity for future generation manufacturing of devices.This talk will focus on the importance of tuning the morphological features of a catalyst as a strategy to improve its optical and photocatalytic properties, focusing on how rationally designing inorganic materials at the nanoscale can lead to morphologies and structures suitable to enhance the performance of industrially and environmentally important processes. The talk will discuss some environmental applications that can be addressed by photoactive multi-component oxide systems synthesized via the bottom–up approach, highlighting their structure-reactivity relationship. Water contamination, in particular, is one of the upfront issues to be solved and complex organic molecules and pharmaceuticals, including antibiotics, are gaining attention due to their abuse and their low degradability. Photocatalytic drugs degradation will be presented as a successful case history [1-3] to provide inspiration to produce cheap, environmentally friendly, stable, and efficient photocatalysts, which hold a great potential for the development of new technologies not only for water remediation applications but also for energy applications in the field of solar fuel production.[1] E. Moretti, L. Storaro, A. Talon, P. Riello, A. Infantes Molina, E. Rodríguez-Castellón, Appl. Catal. B: Environmental 168 (2015) 385.[2] M. Telkhozhayeva, B. Hirsch, R. Konar, E. Teblum, R. Lavi, M. Weitman, B. Malik, E. Moretti, G.D. Nessim, Appl. Catal. B: Environmental 318 (2022) 121872.[3] L. Liccardo, M. Bordin, P.M. Sheverdyaeva, M. Belli, P. Moras, A. Vomiero, E. Moretti, Adv. Funct. Mater. 33 (2023) 2212486.

MnCo2O4 Spinel & Carbon Black coated Nickel Foam Electrode. A Bifunctional Water-Splitting Catalyst?

Hydrogen has the potential to revolutionise how we produce and consume energy. We can meet energy demands without compromising the environment by using renewable sources such as wind, solar and wave power producing low-cost electricity to split the water molecule into its constituent parts. We could then convert Hydrogen back to electricity using a fuel cell, as illustrated in Figure 1. The by-product in this entire process is water, giving a clean technology with no toxic or greenhouses gases. Currently the best performing electrocatalytic materials for water splitting are noble metal based, namely platinum for the hydrogen evolution reaction (HER) and Ruthenium for the oxygen evolution reaction (OER). The use of these materials is unsustainable and makes fuel cells too expensive for commercial applications. We must engineer sustainable, cost-effective alternatives.Nickel foam electrodes display desirable electrocatalytic properties such as a large surface area compared to volume with highly conducting, porous networks, while transition metal dichalcogenides show very good electronic properties with high surface areas and large active sites. In this work we show that it is possible to electrochemically and solvothermally produce CoSex and CoSex composites on a porous nickel foam electrode (NFE). The best performing materials were selected and evaluated via electrochemical impedance spectroscopy. This analysis showed high electrochemical active surface area (ECSA) values and good stability across the selected materials. Scanning electron microscopy (SEM) images reveal that the surfaces of the synthesized materials exhibit distinct morphologies and have been significantly modified. Further electrochemical evaluation of the materials reveals low overpotentials for both hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) thus showing promise as a potential bi-functional electrocatalyst in overall water splitting.References(1) Chaudhari, N. K.; Jin, H.; Kim, B.; Lee, K. Nanostructured Materials on 3D Nickel Foam as Electrocatalysts for Water Splitting. Nanoscale. 2017. https://doi.org/10.1039/c7nr04187j.(2) Minadakis, M. P.; Tagmatarchis, N. Exfoliated Transition Metal Dichalcogenide-Based Electrocatalysts for Oxygen Evolution Reaction. Advanced Sustainable Systems. 2023. https://doi.org/10.1002/adsu.202300193.(3) Sukanya, R.; da Silva Alves, D. C.; Breslin, C. B. Review—Recent Developments in the Applications of 2D Transition Metal Dichalcogenides as Electrocatalysts in the Generation of Hydrogen for Renewable Energy Conversion. J Electrochem Soc 2022, 169 (6). https://doi.org/10.1149/1945-7111/ac7172. Figure 1

(Invited) Quantitative Photonic Characterization and Modelling of Light Emission, Confinement, and Enhancement in Nanostructured Materials

Optical spectroscopy and imaging provide non-destructive, contactless, and fast strategies to study the nature and technological aspects of thin films and nanostructured materials for photonic and optoelectronic applications. Furthermore, the design, engineering, and optimization of such devices requires quantitative information with high-precision standards in measuring and modelling as is the case, for example, in the determination of the optical critical dimension (OCD) in the semiconductor industry. Our application of these strategies to the study of tunable self-assembled nanolasers, hybrid photonic-plasmonic sensors, and photovoltaic devices, among many other materials and devices has led us to the development of i) new modelling strategies based on the Finite-Difference Time-Domain (FDTD) method, and ii) home-made customizable characterization strategies based on spectroscopic ellipsometry (SE). The advantages of the FDTD method include its ability to i) obtain a wide spectral response from one time-domain simulation, ii) model single non-periodic structures, and iii) flexibility and generality to include, for example, non-linear and thermal effects. On its part, SE stands out from other optical techniques because, as a self-referenced and phase sensitive strategy, it can deliver extreme precision and sensitivity and has demonstrated flexibility that has been implemented in multiple spectral ranges and operation conditions. With this in mind, our group has systematically demonstrated the synergic use of FDTD-SE strategy, with complementary strengths and close-matched precision, in a range of materials and devices. We will report the fundamentals, status of our on-going efforts, and a critical review of the perceived limitations and expected outcomes of the FDTD-SE strategy as a quantitative tool for photonic and plasmonic subwavelength structures of interest in optoelectronic, sensing, and energy applications.We gratefully acknowledge the financial support from the RGC (Projects CityU - 11210218, 11219919, 11215121 and 11310122) and ITC (Project ITS/461/18) of HKSAR, China.

Distinct High-Pressure Responses of Halide Perovskites from Bulk to Low Dimension

Hybrid organic-inorganic perovskites (HOIPs) are low-cost and highly efficient optoelectronic and photovoltaic materials for applications in solar cells, light emitting diodes (LEDs), and so on, which is correlated with their intrinsic structures. Now the hybrid perovskite families include three-dimensional (3D) (CH3NH3PbBr3), two-dimensional (2D) ((C4H9NH3)2(CH3NH3)n-1PbnI3n+1) and nanostructured ((CH3NH3PbBr3 nanoparticles) materials. Herein, well understanding the relationship between the cystal structures and the related functional properties of HOIP materials is essential to the application point of view. High pressure up to gigapascal, offers a comprehensive way to study the structure-property correlation of solid materials in the atomic level, where both crystal structures and electronic properties are changed dramatically.In this presentation, high pressure induced dramatically inorganic and organic part changes in 2D HOIPs are comprehensively studied[1,2], as shown in Figure 1. On the other hand, structural phase transition and morphology changes are also explored in 3D HOIP and their nanoparticles[3], as shown in Figure 2. All the high pressure-induced inorganic structural transition is resolved by in situ X-ray powder diffraction (XRD) measurements, morphology change is resolved by transmission electron microscopy (TEM), the correlated optical responses are investigated by absorption and photoluminescence spectroscopy. And the rotational isomerism is evidenced by the vibrational properties of the organic BA chain by Raman spectroscopy combined with the Ab initio calculations.Reference:[1] T Yin, B Liu, J Yan, Y Fang, M Chen, WK Chong, S Jiang, J-L Kuo, J Fang, P L, S-H W, K-P Loh, T-C Sum, T J. White, and Z Xiang, J. Am. Chem. Soc. 141, 1235 (2019).[2] Yin T, Yan H, Abdelwahab I, Lekina Y, Lü X, Yang W, Sun H, Leng K, Cai Y, Shen Z, Loh KP, Nat. Commun. 14, 411 (2023).[3] T Yin, Y Fang, WK Chong, KT Ming, S Jiang, X Li, J-L Kuo, J Fang, T-C Sum, T J. White, J Yan, and Z Xiang, Adv. Mater. 30, 1705017 (2018). Figure 1

(Digital Presentation) On-Chip Micro-Supercapacitors of 3D Carbon Nanotube/Gold Nanocomposites through Silicon-Based MEMS Technology

The high-power and high-frequency response characteristics of supercapacitors have enabled their promising application in fasting charging/discharging scenarios such as power grid stabilization and Internet of Things (IoT). The widespread use of portable electronic devices and the evolution of the IoT have underscored the growing demand for the ongoing miniaturization and enhanced energy autonomy of existing circuit components [1]. Micro-supercapacitors (MSCs) have surfaced as a promising solution to meet these demands, offering superior power density and cycle life compared to similar battery products [2]. However, integrating MSCs with electronic circuits presents significant challenges, often serving as a roadblock to comprehensive system miniaturization. To cater to the requirements of practical application scenarios, particularly in System-in-Package (SiP) and System-on-Chip (SoC) contexts, the fabrication of MSCs requires the use of silicon-based semiconductors or Micro-Electro-Mechanical Systems (MEMS) technology [3]. This strategic approach not only enhances performance but also ensures shorter interconnection distances, more compact dimensions, and increased energy and power density across all components. Emphasizing high power density, elevated energy density, and responsive high-frequency behavior is crucial for the optimal characteristics of MSCs in future applications. As for electrode materials, carbon, which is abundant and cost-effective, has spurred extensive research into various nanostructured carbon-based materials for Electric Double-Layer (EDL) MSCs, including activated carbon, carbon nanotubes (CNTs), carbide-derived carbon, and onion-like carbon [4]. Additionally, transition metal oxides such as ruthenium oxide and manganese oxide, along with conductive polymers like polypyrrole and polyaniline, have proven useful as materials for pseudocapacitive micro supercapacitors [5]. Notably, CNTs fabricated through Chemical Vapor Deposition (CVD) are unequivocally compatible with MEMS microfabrication technology. In the context of EDL MSCs, a dense CNT network structure boosts energy density but impedes ion transport, thereby reducing power density. Conversely, a sparse CNT network structure facilitates ion transport but compromises high-frequency response due to fewer charge transfer paths. Therefore, the development of CNT-based MSCs tailored to practical application needs a more thorough investigation into CNT network structures and their current collector designs.Here, we report the fabrication of on-chip MSCs that are fully compatible with Silicon-based MEMS technology. Figure 1 illustrates the fabrication and characterization process of on-chip MSCs utilizing silicon-based MEMS technology, showing distinct surface morphologies of b-Si nanostructures after CNT growth and Au layer deposition. Figure 2 presents the electrochemical performance of the on-chip MSCs. The CV curves exhibit an ideal rectangular shape at a scan rate of 1 V/s. Even at a high scan rate of 100 V/s, the CV curve maintains a quasi-rectangular shape with minimal distortion, confirming the ultrafast response performance (Fig. 2 (a-b)). The phase angles of the on-chip MSCs are measured to be -68.9° and -66.2° in 1.0 M Na2SO4, and -64.1° and -70.8° in 0.5 M H2SO4 at 120 Hz (Fig. 2 (c)). The absence of a prominent semicircle in the Nyquist plots at high frequencies region implies fast electron transfer and ion diffusion within CNT/Au nanocomposite electrodes. Furthermore, the equivalent series resistances (ESR) are 0.604 Ω·cm2, 0.201 Ω·cm2, 0.504 Ω·cm2, and 0.126 Ω·cm2 for Si-CNT-20 and Si-CNT-20-Au MSCs (Fig. 2 (d)), indicating excellent interfacial contact between the CNT layer and Au current collector and good electrode conductivity. Fig. 2(e) shows that the MSCs deliver a specific capacitance (CA ) of 0.049 mF/cm2, 1.041 mF/cm2, 0.101 mF/cm2, and 1.368 mF/cm2 in 1.0 M Na2SO4 and 0.5 M H2SO4 at 120 Hz, respectively. The relaxation time constant (τ0 ) is calculated to be as short as 1.65 ms for the MSCs (Si-CNT-20-Au), underscoring rapid ion diffusion within electrodes in 0.5 M H2SO4 electrolyte (Fig. 2 (e)).In conclusion, we have successfully used b-Si as the scaffold structure and 3D CNT/Au nanocomposites as the active material for on-chip MSCs application. Significantly, the incorporation of this silicon-based 3D CNT/Au nanocomposite electrode presents promising prospects for the application of MSCs in varied domains, including wearable electronics, IoT devices, and sensor networks.

Pseudocapacitive Storage in Molybdenum Oxynitride Nanostructures Reactively Sputtered on Stainless-Steel Mesh Towards an All-Solid-State Flexible Supercapacitor

Exploiting pseudocapacitance in rationally engineered nanomaterials offers greater energy storage capacities at faster rates. The present research reports a high-performance Molybdenum Oxynitride (MoON) nanostructured material deposited directly over stainless-steel mesh (SSM) via reactive magnetron sputtering technique for flexible symmetric supercapacitor (FSSC) application. The MoON/SSM flexible electrode manifests remarkable Na+-ion pseudocapacitive kinetics, delivering exceptional ~881.83 F.g-1 capacitance, thanks to the synergistically coupled interfaces and junctions between nanostructures of Mo2N, MoO2, and MoO3 co-existing phases, resulting in enhanced specific surface area, increased electroactive sites, improved ionic and electronic conductivity. Employing 3D Bode plots, b-value, and Dunn’s analysis, a comprehensive insight into the charge-storage mechanism has been presented, revealing the superiority of surface-controlled capacitive and pseudocapacitive kinetics. Utilizing PVA-Na2SO4 gel electrolyte, the assembled all-solid-state FSSC (MoON/SSM||MoON/SSM) exhibits impressive cell capacitance of 30.7 mF.cm-2 (438.59 F.g-1) at 0.125 mA.cm-2. Moreover, the FSSC device outputs superior energy density of 4.26 μWh.cm-2 (60.92 Wh.kg-1) and high power density of 2.5 mW.cm-2 (35.71 kW.kg-1). The device manifests remarkable flexibility and excellent electrochemical cyclability of ~91.94% over 10,000 continuous charge-discharge cycles. These intriguing pseudocapacitive performances combined with lightweight, cost-effective, industry-feasible, and environmentally sustainable attributes make the present MoON-based FSSC a potential candidate for energy-storage applications in flexible electronics. Figure 1

Ni3C/Ni3S2 Heterojunction Electrocatalyst for Efficient Methanol Oxidation via Dual Anion Co-modulation Strategy.

Enhancing active states on the catalyst surface by modulating the adsorption-desorption properties of reactant species is crucial to optimizing the electrocatalytic activity of transition metal-based nanostructured materials. In this work, an efficient optimization strategy is proposed by co-modulating the dual anions (C and S) in Ni3C/Ni3S2, the heterostructured electrocatalyst, which is prepared via a simple hot-injection method. The presence of Ni3C/Ni3S2 heterojunctions accelerates the charge carrier transfer and promotes the generation of active sites, enabling the heterostructured electrocatalyst to achieve current densities of 10/100mA cm-2 at 1.37V/1.53V. The Faradaic efficiencies for formate production coupled with hydrogen evolution approach 100%, accompanied with a stability record of 350h. Additionally, operando electrochemical impedance spectroscopy (EIS), in situ Raman spectroscopy, and density functional theory (DFT) calculations further demonstrate that the creation of Ni3C/Ni3S2 heterointerfaces originating from dual anions' (C and S) differentiation is effective in adjusting the d-band center of active Ni atoms, promoting the generation of active sites, as well as optimizing the adsorption and desorption of reaction intermediates. This dual anions co-modulation strategy to stable heterostructure provides a general route for constructing high-performance transition metal-based electrocatalysts.

Unveiling the role of heterophase nanostructure in MnO2-based colorimetric sensors for ascorbic acid detection.

Nanozymes based on manganese oxide (MnO2) are demonstrated to be promising probes in colorimetric sensing applications. In this study, the r-MnO2/β-MnO2 heterophase nanostructure was simply prepared by a calcination process with controllable temperature. The characterization of the nanostructured material was confirmed by SEM, UV-vis spectroscopy, Raman, TGA-DSC, and XRD analysis. The r-MnO2/β-MnO2 exhibits a remarkably good catalytic activity in the oxidation process of 3,3',5,5'-tetramethylbenzidine (TMB) compared withthe r-MnO2 or Mn2O3 nanostructure owing to its heterophase junctions. The enhanced performance of the colorimetric sensor for ascorbic acid (AA) detection was investigated using the r-MnO2/β-MnO2 heterophase nanostructure as probe. The r-MnO2/β-MnO2 material enhanced the monitoring of AA in the wide linear range from 1µM to 50μM with alimit of detection of0.84µM. This work presents a promising and straightforward approach for the construction of MnO2-based colorimetric sensor and their practical application in plant growth monitoring.

Efficient Ionovoltaic Energy Harvesting via Water-Induced p-n Junction in Reduced Graphene Oxide.

Water motion-induced energy harvesting has emerged as a prominent means of facilitating renewable electricity from the interaction between nanostructured materials and water over the past decade. Despite the growing interest, comprehension of the intricate solid-liquid interfacial phenomena related to solid state physics remains elusive and serves as a hindrance to enhancing energy harvesting efficiency up to the practical level. Herein, the study introduces the energy harvester by utilizing inversion on the majority charge carrier in graphene materials upon interaction with water molecules. Specifically, various metal electrode configurations are employed on reduced graphene oxide (rGO) to unravel its distinctive charge carriers that experience the inversion in semiconductor type upon water contact, and exploit this characteristic to leverage the efficacy of generated electricity. Through the strategic arrangement of the metal electrodes on rGO membrane, the open-circuit voltage (Voc) and short-circuit current (Isc) have exhibited a remarkable augmentation, reaching 1.05V and 31.6µA, respectively. The demonstration of effectively tailoring carrier dynamics via electrode configuration expands the practicality by achieving high power density and elucidating how the water-induced carrier density modulation occurs in 2D nanomaterials.

Biosynthesis of microrubble-shaped nanoporous Co3O4/rGO NCs using leaves extract of Neolamarckia cadamba and its antibacterial/antioxidant performance

Nowadays, the whole globe is paying great attention for the sustainable development, eco-friendly and economical production of nanostructures materials. With this motivation, the present work portrayed one-step ‘in-situ’ bioinspired green fabrication of Co3O4–reduced graphene oxide nanocomposites (Co3O4–rGO NCs) for the first time utilizing an aqueous leaf extract of Neolamarckia cadamba. As-fabricated NCs were characterized by several analytical and electron microscopic techniques viz. X-ray diffraction (XRD), Fourier Transform-Infrared (FT-IR), Energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), BET (Brunauer-Emmett-Teller), Scanning electron microscopy (SEM), and Transmission electron microscopy (TEM) to evaluate their phases, structure, shape, composition, chemical state, porosity, optical and morphological aspects. The XRD study revealed a cubic spinel symmetry of NCs, while crystallite size estimated around 25 nm. TEM spectroscopy exposed an average particle size 8–10 nm of Co3O4 grown on the surface of reduced graphene oxide (rGO NCs), whereas SEM analysis showed sharped microrubble-shaped morphology. The formation of NCs by doping metal oxide with rGO through in-situ method were confirmed by XRD, EDS, Raman, and XPS spectroscopy. The BET study estimated the specific surface area and pore size of NCs as 98 m2/g and 8.9 nm respectively. The Co3O4–rGO NCs demonstrated an effective bactericidal activity against S. aureus, E. coli, K. pneumoniae, and B. subtillis. Prominently it was found that, a significant antibacterial activity seen against E. coli and S. aureus at a concentration 0.1 mg/100 µL may be due to scaffold morphology, nanoscale-structures and nanoporosity of the NCs. Due to receiving significant antibacterial activity, material’s molecular docking was assessed. Furthermore, an antioxidant activity of leaf extract and NCs was evaluated by DPPH method. An outstanding biological study of bioinspired NCs revealed that material could be used as a potent antimicrobial agent.

Cu-MOF-derived carbon nanomaterials as efficient catalysts for the reduction of nitro compounds

In this paper, we have synthesized a new light blue crystal Cu-MOF-1 with Cu(II) as the central metal ion by using two mixed ligands, where N,N’-bis(3-pyridyl)adipamide (3-bpaa) and fumaric acid (H2FA). Taking this material as the precursor of the study, it is found that Cu-MOF-1 possesses a single-crystal-to-single-crystal (SCSC) transition phenomenon, using its structure in the free state of water molecules in the heating process will be dehydrated and thus transformed into dark blue crystal Cu-MOF-2. This color distinctive change can be intuitively identify the temperature conversion, and thus be applied to the direction of the temperature sensing. Moreover, using Cu-MOF-1 as a precursor, the carbon-based nanostructured materials (Cu@X) of Cu and CuxO were derived from Cu-MOF-1 as a precursor in a straightforward and effective a single-step pyrolysis under different temperatures (400 °C, 600 °C, 800 °C and 1000 °C). As a result, Cu@1000 shown good activity (100 % conversion within 5 min) in the reduction of 4-nitrophenol (4-NP) by the presence of sodium borohydride (NaBH4) at mild circumstances, yielding a rate constant (Kapp) of 1.699 min−1. This remarkable performance is due to the utilization of both the uniform distribution of Cu-based nanoparticals (CuNPs) in the carbon matrix and the abundance of defect sites in the surface. This paper describes innovative MOF-derived catalysts that can be employed in a range of useful applications.

Synthesis and characterization of hierarchically mesoporous silica nanoparticles templated by polymer-surfactant complexes

The mesomorphous complex of poly(acrylic acid) and cationic surfactant as templates are widely used to prepare hierarchically meso-structured materials. Here, the effects of different cationic surfactant in complexes on the morphology and nano-structure of the mesoporous silica materials were studied. It was found chain length of hydrophobic tail significantly affected the meso-structure. With the increase of the chain length, three different of meso-structure of disordered, 3-dimentional cubic ordered, 2-dimentional hexagonal could be achieved. Significantly, the hierarchically mesoporous silica nanoparticles (50–100 nm) with 2-dimentional hexagonal meso-structure (P6mm) were firstly obtained in polymer-surfactant synthetic system.

Applications of nanostructured materials for severe acute respiratory syndrome-CoV-2 diagnostic

There is a growing concern that severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) infections will continue to rise, and there is now no safe and effective vaccination available to prevent a pandemic. This has increased the need for rapid, sensitive, and highly selective diagnostic techniques for coronavirus disease (COVID-19) detection to levels never seen before. Researchers are now looking at other biosensing techniques that may be able to detect the COVID-19 infection and stop its spread. According to high sensitivity, and selectivity that could provide real-time results at a reasonable cost, nanomaterial show great promise for quick coronavirus detection. In order to better comprehend the rapid course of the infection and administer more effective treatments, these diagnostic methods can be used for widespread COVID-19 identification. This article summarises the current state of research into nanomaterial-based biosensors for quick SARS‑CoV‑2 diagnosis as well as the prospects for future advancement in this field. This research will be very useful during the COVID-19 epidemic in terms of establishing rules for designing nanostructure materials to deal with the outbreak. In order to predict the spread of the SARS-CoV-2 virus, we investigate the advantages of using nano-structure material and its biosensing applications.

Thermoelectric bismuth telluride nanostructures fabricated by electrodeposition within flexible templates

Bismuth telluride, a highly efficient thermoelectric material, stands out for applications around room temperature in wearable devices. By harnessing the thermal gradient established between the human body and ambient temperature, we can generate useable electricity. Notably, bismuth telluride nanostructures exhibit significantly lower thermal conductivities compared to their bulk counterparts. As a result, the thermoelectric efficiency achieved is notably higher. Our research focuses on developing efficient nanostructured materials based on bismuth telluride inside a flexible substrate made of polyester. We employ scalable methods, such as template-assisted electrochemical deposition, to fabricate these nanostructures. In this study, we present an approach to the development of flexible nanostructured thermoelectric materials. Despite using a reduced quantity of active material, our electrochemically deposited nanostructures inside a flexible template demonstrate a remarkable performance. They exhibit 24 % of the Power Factor reported for conventional electrochemically fabricated Bi2Te3 thin films, and notably, they even surpass the Power Factor reported for flexible Bi2Te3-based inks used in the creation of flexible generators. This achievement underscores the potential of our method in the advancement of efficient, flexible thermoelectric devices.

Fabrication of iron manganese oxide-reduced graphene oxide nanocomposite: A highly effective synergistic electrocatalyst for sensitive metronidazole detection

Efficient 2D-inorganic spinel perovskites nanostructure materials are used as potential candidates for highly sensitive detection of harmful substances present in the environment. In this regard, a facile one-pot hydrothermal synthesis was employed to fabricate nanocomposite material containing iron manganese oxide (FeMn2O4) decorated with reduced graphene oxide (rGO) which is used as an electrochemical detection of metronidazole (MTZ). The crystalline nature and structural insights of the as-synthesized FeMn2O4-rGO nanocomposite were established using various spectroscopic and electrochemical techniques. Distinctively FeMn2O4-rGO nanocomposite fashioned glassy carbon electrode (GCE) showed excellent linear range (0.01–512.2 μM), sensitivity (71.4 μA mM−1 cm−2), limit of detection (0.0129 μM), reproducibility, stability and resist-interference capability towards metronidazole (MTZ) antibiotic drug. In addition, the fabricated FeMn2O4-rGO/GCE electrochemical sensor exhibited a remarkable MTZ detection in spiked water as well as urine samples with better recovery percentages supporting its facile and feasible nature for environmental applications. The present work established the fabrication of FeMn2O4-rGO/GCE nanocomposite for effective determination of antibiotic drugs in real sample analysis.

Carbon nanomaterials in flexible wearable sensors

Recent remarkable advances in flexible and wearable functional electronics have been achieved due to their advantages of lightweight, convenience to detect complex measured objects, and flexibility, which makes electronic equipment develop from a rigid system to a flexible system. Flexible materials toward wearable devices present a huge market prospect, which demonstrate promise in healthcare, human motion detection, biomedicine, environmental monitoring, and other fields. Unique physical and chemical properties are the critical characteristics of flexible wearable sensors, and the huge surface-to-volume ratio facilitates carbon nanomaterials to be used in various flexible sensors. This review comprehensively introduces the structure, properties, and preparation of carbon nanomaterials like carbon nanotubes, graphene, and MXene. The sensing mechanism of the sensor is outlined, and flexible sensors based on carbon nanomaterials in detecting targets such as pressure, temperature, and gases are proposed. Enhancement of conductivity, sensing factor, and sensitivity of carbon nanomaterials by modifying their structure or preparing composites is presented in detail. Finally, this paper outlines the challenges associated with implementing carbon nanomaterials within the field of flexible wearable sensors and future development.

Influence of fibril aspect ratio, chemical functionality, and volume fraction on the mechanical properties of cellulose nanofibril materials

Nanocellulose has emerged as a widely utilized building block in nanostructured materials due to its availability, sustainability, large surface area, and high stiffness and aspect ratio. The wet or dry elastoplastic properties of these materials are determined by the fibrils' stiffness, chemical properties, hemicellulose content, and the number of fibril contacts. However, the specific contributions and relative importance of each factor remain unclear. Therefore, this work was devoted to systematically comparing the material properties of gels, aerogels, and wet and dry sheets prepared from CNFs with different aspect ratios, chemical functionality, and hemicellulose content. The fibrils were prepared by chemical and mechanical processing of different pulps. By preserving the native structure as much as possible, higher aspect ratio fibrils can be obtained, which allows for the development of more mechanically robust materials. The results demonstrate that higher aspect ratios lead to more interconnected networks at a lower solids concentration, resulting in a more evenly distributed stress and longer-range stress transfer, yielding stiffer and more ductile materials. The most important finding was that the aspect ratio influences the network formation, resulting in different network topologies. The results were also compared to earlier published data and integrated into a theoretical beam-bending model for a complete elastoplastic description of the network properties, including the influence of fibril aspect ratio and chemical functionality. This information improves our understanding and description of nanofibril networks for which general models have been missing. It can be used to optimize nanofibril preparation and, hence, the resulting eco-friendly materials.

Quantitative 3D structural analysis of small colloidal assemblies under native conditions by liquid-cell fast electron tomography

Electron tomography has become a commonly used tool to investigate the three-dimensional (3D) structure of nanomaterials, including colloidal nanoparticle assemblies. However, electron microscopy is typically done under high-vacuum conditions, requiring sample preparation for assemblies obtained by wet colloid chemistry methods. This involves solvent evaporation and deposition on a solid support, which consistently alters the nanoparticle organization. Here, we suggest using electron tomography to study nanoparticle assemblies in their original colloidal liquid environment. To address the challenges related to electron tomography in liquid, we devise a method that combines fast data acquisition in a commercial liquid-cell with a dedicated alignment and reconstruction workflow. We present the advantages of this methodology in accurately characterizing two different systems. 3D reconstructions of assemblies comprising polystyrene-capped Au nanoparticles encapsulated in polymeric shells reveal less compact and more distorted configurations for experiments performed in a liquid medium compared to their dried counterparts. A similar expansion can be observed in quantitative analysis of the surface-to-surface distances of self-assembled Au nanorods in water rather than in a vacuum, in agreement with bulk measurements. This study, therefore, emphasizes the importance of developing high-resolution characterization tools that preserve the native environment of colloidal nanostructures.