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Plasmonic nanoparticle clusters promise to support unique engineered electromagnetic responses at optical frequencies, realizing a new concept of devices for nanophotonic applications. However, the technological challenges associated with the fabrication of three-dimensional nanoparticle clusters with programmed compositions remain unresolved. Here, we present a novel strategy for realizing heterogeneous structures that enable efficient near-field coupling between the plasmonic modes of gold nanoparticles and various other nanomaterials via a simple three-dimensional coassembly process. Quantum dots embedded in the plasmonic structures display ∼56 meV of a blue shift in the emission spectrum. The decay enhancement factor increases as the total contribution of radiative and nonradiative plasmonic modes increases. Furthermore, we demonstrate an ultracompact diagnostic platform to detect M13 viruses and their mutations from femtoliter volume, sub-100 pM analytes. This platform could pave the way toward an effective diagnosis of diverse pathogens, which is in high demand for handling pandemic situations.

Inorganic two-dimensional (2D) materials offer a new approach to control mass diffusion at the nanoscale. Controlling ion transport in nanofluidics is key to energy conversion, energy storage, water purification, and numerous other applications wherein persistent challenges for efficient separation must be addressed. We herein discuss the recent development of 2D membranes in the emerging field of energy harvesting, water desalination, and proton/Li-ion production in the context of green energy and environmental technology. We highlight the fundamental mechanisms, 2D membrane fabrication, and challenges toward practical applications. Finally, we outline the fundamental issues of thermodynamics and kinetics along with potential membrane designs that must be resolved to bridge the gap between lab-scale experiments and production levels. This article is protected by copyright. All rights reserved.

MXene-blanketed Au nanoparticle assembly with energy level alignment effectively facilitates the charge transfer effect while securing the electromagnetic effect by guiding the analyte near to hotspot center for surface enhanced Raman scattering.

In this study, we successfully demonstrate the synthesis of a novel necklace-like Co, Fe, and N co-doped one-dimensional (1D)-assembly of hollow carbon nanoboxes (1D-HCNB-x) and its potential for supercapacitor application.

Enlargement of micropores in zeolitic imidazolate framework particles into mesopores is achieved via an ethylene glycol-assisted aqueous etching method. The etched carbon shows a higher specific capacitance than unetched one at high scan rates.

Two-dimensional (2D) transition metal dichalcogenides (TMDs) have attracted considerable attention owing to their synergetic effects with other 2D materials, such as graphene and hexagonal boron nitride, in TMD-based heterostructures. Therefore, it is important to understand the physical properties of TMD-TMD vertical heterostructures for their applications in next-generation electronic devices. However, the conventional synthesis process of TMD-TMD heterostructures has some critical limitations, such as nonreproducibility and low yield. In this paper, we synthesize wafer-scale MoS2-WS2 vertical heterostructures (MWVHs) using plasma-enhanced chemical vapor deposition (PE-CVD) via penetrative single-step sulfurization discovered by time-dependent analysis. This method is available for fabricating uniform large-area vertical heterostructures (4 in.) at a low temperature (300 °C). MWVHs were characterized using various spectroscopic and microscopic techniques, which revealed their uniform nanoscale polycrystallinity and the presence of vertical layers of MoS2 and WS2. In addition, wafer-scale MWVHs diodes were fabricated and demonstrated uniform performance by current mapping. Furthermore, mode I fracture tests were performed using large double cantilever beam specimens to confirm the separation of the MWVHs from the SiO2/Si substrate. Therefore, this study proposes a synthesis mechanism for TMD-TMD heterostructures and provides a fundamental understanding of the interfacial properties of TMD-TMD vertical heterostructures.

Although considerable studies have focused on suppressing polysulfide shuttling in lithium–sulfur (Li–S) batteries by modifying separator surfaces, simultaneously achieving fast Li-ion transport and full active-material use remains a technological limitation. Herein, we present an effective method for anchoring zwitterionic sulfobetaine (SB) moieties on a separator surface that concurrently facilitates both selective Li-ion transport and polysulfide conversion. The platform that anchors the zwitterions was sequentially constructed by first introducing a polydopamine (PDA) coating to promote surface wettability and activity for further covalent SB binding using the aza-Michael addition reaction, which enabled the formation of a robust PDA/SB-coated separator. The zwitterion-functionalized separator exhibited a significant enhancement in ionic conductivity from 0.837 to 1.827 mS cm−1 and the Li-ion transference number from 0.186 to 0.511 due to the facile dissociation of lithium salts and selectively promoted the interactions between Li cations and the anionic sulfonate SB end groups. Along with the redox promoting effect, the polysulfide shuttling was further inhibited through strong dipole–dipole interactions. Furthermore, as Li2S precipitation was effectively mediated by the SB zwitterions and improved sulfur-conversion kinetics was achieved, outstanding Li–S battery performance with an initial discharge capacity of 1365.9 mA h g−1 was obtained, while delivering an ultra-low capacity decay rate of 0.034% during long-term cycling (up to 1200 cycles) at 3.0C, even at a high load. Therefore, we believe that the proposed study harnessing zwitterionic separator functionalization would enable the rational design of functional separators for the promoted kinetics and suppressed diffusion of unfavorable reaction intermediates for high performance batteries.

MXenes have received much attention as promising candidates for noble metal-free hydrogen evolution reaction (HER) electrocatalysts due to their high electrical conductivity, surface hydrophilicity, abundant surface functional groups, and great potential for rational hybridization with other materials. Herein, a novel porous monolayered-Ti3C2Tx@NiCoP (P-Ti3C2Tx@NiCoP) nanostructure was synthesized with uniform distribution of bimetallic compounds for improved charge transfer capability and electrocatalytic activity. In experiments, H2O2-utilized oxidation formed a highly mesoporous structure with a maximized surface area of monolayered MXenes as the support. A subsequent solvothermal process followed by phosphidation enabled successful anchoring of highly HER-active NiCoP nanoclusters onto abundantly exposed terminal edges of the P-Ti3C2Tx support. The structural porosity of the P-Ti3C2Tx nanoflakes played an important role in creating additional room for embedding catalytically active species while stably imparting high electrical conductivity to accelerate charge transfer to NiCoP nanoclusters. With structural modification and effective hybridization, P-Ti3C2Tx@NiCoP showed highly enhanced HER activity with significantly lower overpotentials of 115 and 101 mV at a current density of -10 mA cm-2 in 0.5 M H2SO4 and 1.0 M KOH, respectively, along with showing long-term stability over 60 h. As such, our approach of designing structurally modified-Ti3C2Tx and hybridizing with other electrocatalytically active species would function as a solid platform for implementing Ti3C2Tx-based hetero-nanostructures to achieve state-of-the-art performance in next-generation energy conversion applications.

Mesoporous TiO2 films are synthesized through evaporation-induced self-assembly using poly(ethylene oxide-b-ε-caprolactone) diblock copolymers as a soft-template. Using small-angle X-ray scattering and scanning electron microscopy, we investigate the effect of the TiO2/PEO-b-PCL ratio on the resulting nanoarchitectonic structure. After sputter-coating Au and Pt layers, these Au/TiO2 and Pt/TiO2 nanocomposite films display drastically enhanced photodegradation of rhodamine 6G under ultraviolet irradiation, due to the metal films inhibiting the rapid recombination of photogenerated charge carriers.

Carbonyl compounds have potential for use as cathode materials of secondary batteries because of their large specific capacities, stable redox active centers, high efficiencies and ability to regenerate, however their intrinsic solubilities and low electrical conductivities present challenges to hinder their practical utilization. Here, three-dimensional nanoporous polyquinoneimines (PQ) were synthesized by hydrothermal polymerization reactions, and examined as electrode materials in lithium-ion batteries to solve these problems of solubility and electronic conductivity. The large specific surface area (116.95 m2 g−1) and abundant pore structure (0.2428 cm3 g−1) of the PQ, which were formed by the anisotropic growth of nanosized rose flakes, shortened the lithium-ion diffusion path and reduced lithium solubility. The capacities of the PQ electrodes of 1 mg cm−2 were 228 (1st cycle; theoretical capacity of PQ with 4 electron reaction is 228 mAh g−1) and 103 (1000th) mAh g−1 at 50 mA g−1, and the declined rate per cycle at 200 mA g−1 was only 0.05% (0.077 mAh g−1 per cycle) within the first 1000 cycles. The capacity of the 500th cycle with a high load of 3 mg cm−2 was 123 mAh g−1, exhibiting a coulombic efficiency of 99%. The molecular structure during lithiation was calculated with density functional theory and showed that the robust bridge bond formed and promoted the electrochemical activity of the charge/discharge process.

A new chemical method is developed for the preparation of a unique one-dimensional (1D) Sn(IV) hydroxide nanofluid. The 1D-Sn(IV) hydroxide nanowires of ca. 600 nm in length and ca. 25 nm in width yield transparent glass type flakes when the nanofluid is dried in air. The stability of the system, keeping it safe from sedimentation even after a year, is believed to rely on its high zeta-potential of ca. 55 mV (± 2.5 mV). We extensively investigate the thermal conductivity and viscosity of the system in order to evaluate its nanofluidic merits, resulting in thermal conductivity exceeding 1 W m−1 K−1. The nanofluid is further investigated for nonlinear optics (NLO) applications, revealing a reversible switching from positive Z-scan (convex lens) to negative Z-scan (concave lens) of the nonlinear phase when the laser power is tuned from 500 to 1000 μW.

This paper describes adaptive sliding mode control of a steer-by-wire (SBW) system to guarantee rack position tracking performance in various driving situations. The proposed control algorithm was developed using only motor position sensors (MPS) without information on tire/road friction. A stiffness parameter adaptation law was designed to compensate for disturbances in the SBW rack system. It is demonstrated that the proposed adaptation algorithm provides good tracking performance without using an additional gain tuning approach under various road conditions. Moreover, in the proposed algorithm, a dynamic stiffness model has been developed to improve rack position tracking performance under a zero vehicle speed scenario. In a dynamic stiffness model, the stiffness center is not fixed but changes depending on the actual rack position. In the event than an SBW vehicle is parking, it is important to ensure rack position tracking performance at low and zero vehicle speeds. Computer simulations and vehicle tests were performed under various driving situations to test the performance of the proposed control algorithm. The results demonstrate that the proposed control algorithm ensures tracking performance on dry asphalt and wet road conditions, as well as at zero vehicle speed.

Highly efficient nanoparticle-on-metallic-mirror (NPOM) systems with a large gap size exhibiting good plasmonic enhancement are desirable for numerous practical applications. Careful, explicit design optimization strategies are required for preparing NPOMs and it is especially important in utilizing spherical nanoparticles. In this work, a new design blueprint for evaluating the role of random facets in spherical nanoparticles was investigated in detail to realize optimal NPOMs. We found that a precise single facet positioned at the nanoparticle's cavity outperformed multiple random facets due to the gap mode contribution. Differences and changes in the plasmonic modes were interpreted with the help of three-dimensional surface charge density mappings. A high-performance, single, bottom-faceted NPOM device with a large gap size (example 20 nm) was realized having 80-50% facet design, resulting in excellent gap mode enhancement. We succeeded in fabricating single bottom-faceted NPOMs (the non-facet region had a smooth spherical surface) with a large-scale unidirectionality (2 cm × 1.5 cm). Simulations and experimental characterizations of these components displayed excellent agreement. Our highly efficient NPOM design with a large gap size(s) enables interesting practical applications in the field of quantum emitters, energy devices, fuel generation and plasmon chemistry.

Correction for ‘Co, Fe and N co-doped 1D assembly of hollow carbon nanoboxes for high-performance supercapacitors’ by Minjun Kim et al., J. Mater. Chem. A, 2022, 10, 24056–24063, https://doi.org/10.1039/D2TA06950D.

Herein, the synergistic effects of hollow nanoarchitecture and high specific surface area of hollow activated carbons (HACs) are reported with the superior supercapacitor (SC) and capacitive deionization (CDI) performance. The center of zeolite imidazolate framework-8 (ZIF-8) is selectively etched to create a hollow cavity as a macropore, and the resulting hollow ZIF-8 (HZIF-8) is carbonized to obtain hollow carbon (HC). The distribution of nanopores is, subsequently, optimized by KOH activation to create more nanopores and significantly increase specific surface area. Indeed, as-prepared hollow activated carbons (HACs) show significant improvement not only in the maximum specific capacitance and desalination capacity but also capacitance retention and mean desalination rates in SC and CDI, respectively. As a result, it is confirmed that well-designed nanoarchitecture and porosity are required to allow efficient diffusion and maximum electrosorption of electrolyte ions.

Exploration of advanced carbon anode material is the key to circumventing the sluggish kinetics and poor rate capability for potassium ion storage. Herein, a synergistic synthetic strategy of engineering both surface and structure is adopted to design N, S co-doped carbon nanotubes (NS-CNTs). The as-designed NS-CNTs exhibit unique features of defective carbon surface, hollow tubular channel, and enlarged interlayer space. These features significantly contribute to a large potassium storage capacity of 307 mA h g

Over the past few decades, most cities worldwide have experienced a rapid expansion with unprecedented population growth and industrialization. Currently, half of the world’s population is living in urban areas, which only account for less than 1% of the Earth. A rapid and unplanned urban expansion, however, has also resulted in serious challenges to sustainable development of the cities, such as traffic congestion and loss of natural environment and open spaces. This study aims at modeling and predicting the expansion of urban areas in South Korea by utilizing an explainable artificial intelligence (XAI) model. To this end, the study utilized the land-cover maps in 2007 and 2019, as well as several socioeconomic, physical, and environmental attributes. The findings of this study suggest that the urban expansion tends to be promoted when a certain area is close to economically developed area with gentle topography. In addition, the existence of mountainous area and legislative regulations on land use were found to significantly reduce the possibility of urban expansion. Compared to previous studies, this study is novel in that it captures the relative importance of various influencing factors in predicting the urban expansion by integrating the XGBoost model and SHAP values.

Organic photovoltaics (OPVs) are a promising next-generation photovoltaic technology with great potential for wearable and transparent device applications. Over the past decades, remarkable advances in device efficiency close to 20 % have been made for bulk heterojunction (BHJ)-based OPV devices with long-term stability, and room for further improvements still exists. In recent years, ancillary components have been demonstrated as effective in improving the photovoltaic performance of OPVs by controlling the optoelectronic and morphological properties of BHJ blends. Herein, an updated understanding of polymer-based blend OPVs is provided, and the role and impact of ancillary components in various blend systems are categorized and discussed. Lastly, a strategic perspective on the ancillary components of blend-based OPVs for commercialization is provided.

In this study, three-dimensional (3D) ZIF-8-derived carbon (ZIF-8C) polyhedrons have been successfully coated with polydopamine (PDA) nanothin layer via a facile synthetic method that exploits oxidative self-polymerization of dopamine in alkaline solutions. It is observed that ca. 20 nm of PDA nanothin film is coated on ZIF-8C surface with a good homogeneity. Our results show clear morphological changes in core-shell structured PDA-coated ZIF-8C (ZIF-8C@PDA) as compared to bare ZIF-8C. In addition, the cyclic voltammetry shows conspicuous redox peaks in ZIF-8C@PDA. The observed redox activity is attributed to a series of redox reactions of oxygen species of catechol and quinone groups of PDA. With superior adhesive property and redox activity as additional surface functionality, ZIF-8C@PDA can be used in various applications, especially in energy storage applications in the future.

Carbon materials, especially N-doped carbon materials with a one-dimensional (1D) hollow structure, have attracted great attention as one of the most efficient and eco-friendly catalysts for advanced oxidation processes (AOPs). The complex synthesis process of 1D hollow carbon however remains a major challenge in meeting the growing demand for it as a superior carbon-based catalyst. Herein, we demonstrate a facile strategy to synthesize 1D hollow carbon nanofibers (HCNFs) in a scalable manner. In this study, zeolitic imidazolate framework-8 (ZIF-8)/polyacrylonitrile (PAN) fibers were fabricated via electrospinning, and subsequent pyrolysis of the as-prepared ZIF-8/PAN composite nanofibers produced HCNFs. With excellent structural advantages and N-doped composition, HCNFs exhibited a remarkable level of catalytic degradation of tetracycline (TC) in the peroxymonosulfate (PMS) activation system. Furthermore, the HCNFs also showed good mechanical flexibility. A catalytic device was then constructed to explore the potential applications of HCNFs.

Herein, poly(3-hexylthiophene) films with periodic wavy surface structures are generated upon laser irradiation at a wavelength of 530 nm using a pulse duration of 5 ns and a repetition frequency of 10 Hz. The optical properties of the films irradiated with 1200, 3000, and 6000 pulses, respectively, are studied using various techniques.

Mesostructured polydopamine (PDA) coating has been successfully achieved on the surface of zeolitic imidazolate framework-8 (ZIF-8) particles by incorporating Pluronic F127 (with a pore-expanding agent, 1,3,5-trimethylbenzene) as a pore-directing agent during dopamine polymerization. Upon pyrolysis at high temperatures, mesostructured PDA-coated ZIF-8 particles become hierarchically porous double-shell carbons (HPDCs) with a wide pore size distribution ranging from micro- and meso- to macropores. The formation of a hollow inner shell progresses initially with the shrinkage of ZIF-8 at the periphery where the interface interactions with mesostructured PDA exist, and then the subsequent disintegration of the ZIF-8 core at higher temperatures occurs. Our HPDCs prepared in this study feature physical and electrochemical advantages of hierarchically porous carbons such as high electrochemically accessible surface area, short diffusion distance, and high mass-transfer rate, thus demonstrating significantly improved ion diffusion and surface-enhanced high specific capacitance at high charge-discharge rates. HPDC5.0 therefore exhibits the capacitance retention of up to 76.7% from 1 to 10 A g-1 and maximum specific capacitance of 344.7 F g-1 at 1 mV s-1. It also possesses superior electrochemical stability with about 108% capacitance retention even after 10,000 consecutive cycles of galvanostatic charge-discharge at 10 A g-1.

Layered transition metal dichalcogenide (LTMD)/carbon nanocomposites obtained by incorporating conductive carbons such as graphene, carbon nanotubes (CNT), carbon nanofibers (CF), hybrid carbons, hollow carbons, and porous carbons exhibit superior electrochemical properties for energy storage and conversion. Due to the incorporation of carbon into composites, the LTMD/carbon nanocomposites have the following advantages: (1) highly efficient ion/electron transport properties that promote electrochemical performance; (2) suppressed agglomeration and restacking of active materials that improve the cycling performance and electrocatalytic stability; and (3) unique structures such as network, hollow, porous, and vertically aligned nanocomposites that facilitate the shortening of the ion and electrolyte diffusion pathway. In this context, this review introduces and summarizes the recent advances in LTMD/carbon nanocomposites for electrochemical energy-related applications. First, we briefly summarize the reported synthesis strategies for the preparation of LTMD/carbon nanocomposites with various carbon materials. Following this, previous studies using rationally synthesized nanocomposites are discussed based on a variety of applications related to electrochemical energy storage and conversion including Li/Na-ion batteries (LIBs/SIBs), Li-S batteries, supercapacitors, and the hydrogen evolution reaction (HER). In particular, the sections on LIBs and the HER as representative applications of LTMD/carbon nanocomposites are described in detail by classifying them with different carbon materials containing graphene, carbon nanotubes, carbon nanofibers, hybrid carbons, hollow carbons, and porous carbons. In addition, we suggest a new material design of LTMD/carbon nanocomposites based on theoretical calculations. At the end of this review, we provide an outlook on the challenges and future developments in LTMD/carbon nanocomposite research.

This research was supported by the Basic Science Research Program of the National Research Foundation of Korea (NRF), funded by the Ministry of Education, Science and Technology (NRF-2015R1A1A1A05027848). K. Kim was supported by the Occasional Technology Development Project for Industrial Site Core Technology of the Ministry of Trade, Industry and Energy (No. 10054694).

Mesoporous noble metals and their patterning techniques for obtaining unique patterned structures are highly attractive for electrocatalysis, photocatalysis, and optoelectronics device applications owing to their expedient properties such as high level of exposed active locations, cascade electrocatalytic sites, and large surface area. However, patterning techniques for mesoporous substrates are still limited to metal oxide and silica films, although there is growing demand for developing techniques related to patterning mesoporous metals. In this study, the first demonstration of mesoporous metal films on patterned gold (Au) substrates, prefabricated using photolithographic techniques, is reported. First, different growth rates of mesoporous Au metal films on patterned Au substrates are demonstrated by varying deposition times and voltages. In addition, mesoporous Au films are also fabricated on various patterns of Au substrates including stripe and mesh lines. An alternative fabrication method using a photoresist insulating mask also yields growth of mesoporous Au within the patterning. Moreover, patterned mesoporous films of palladium (Pd) and palladium-copper alloy (PdCu) are demonstrated on the same types of substrates to show versatility of this method. Patterned mesoporous Au films (PMGFs) show higher electrochemically active surface area (ECSA) and higher sensitivity toward glucose oxidation than nonpatterned mesoporous Au films (NMGF).

Biomass-derived carbons are widely studied as cost-effective and high-performance energy storage materials due to their high specific surface area, abundance, and facile synthetic methods. Through widespread research, a number of strategies can be implemented to maximize specific capacitance and power. Among the different approaches to improve the energy storage performance of biomass-derived carbons, an increase of specific surface area and the introduction of heteroatom doping are usually effective strategies. As such, in this study, we utilize sorghum stem biomass to obtain porous carbonaceous forms, and subsequent KOH activation to increase the porosity and surface area. The resulting activated sorghum stem-derived porous carbon materials exhibit significantly higher specific capacitance compared to their pre-activated carbon. Capacitive deionization (CDI) that is used to deionize water is also studied to demonstrate the versatility of sorghum stem-derived porous carbon. A similar performance trend is observed for both supercapacitor and CDI for all carbon samples because both applications exploit the electrostatic double-layer capacitance behavior of carbon materials.

The hybrid metal-organic frameworks (MOFs) with different Zn2+/Co2+ ratios are synthesized at room temperature with deionized water as the solvent. This use of deionized water can increase the yield of hybrid MOFs (up to 65&ndash, 70%). After the pyrolysis, the obtained nanoporous carbons (NPCs) show a decrease in the surface area, in which the highest surface area is 655 m2 g&minus, 1. The as-prepared NPCs are subjected to activation with KOH in order to increase their surface area and convert cobalt nanoparticles (Co NPs) to Co oxides. These activated carbons are applied to electrical double-layer capacitors (EDLCs) and pseudocapacitors due to the presence of CoO and Co3O4 nanoparticles in the carbon framework, leading to significantly enhanced specific capacitance as compared to that of pristine NPCs. This synthetic method can be utilized in future research to enhance pseudocapacitance further while maintaining the maximum surface area of the carbon materials.

Mesoporous TiO2 is attracting increasing interest due to properties suiting a broad range of photocatalytic applications. Here we report the facile synthesis of mesoporous crystalline TiO2-B nanobelts possessing a surface area as high as 80.9 m2 g−1 and uniformly-sized pores of 6−8 nm. Firstly, P25 powders are dissolved in NaOH solution under hydrothermal conditions, forming sodium titanate (Na2Ti3O7) intermediate precursor phase. Then, H2Ti3O7 is successfully obtained by ion exchange through acid washing from Na2Ti3O7 via an alkaline hydrothermal treatment. After calcination at 450 °C, the H2Ti3O7 is converted to a TiO2-B phase. At 600 °C, another anatase phase coexists with TiO2-B, which completely converts into anatase when annealed at 750 °C. Mesoporous TiO2-B nanobelts obtained after annealing at 450 °C are uniform with up to a few micrometers in length, 50−120 nm in width, and 5−15 nm in thickness. The resulting mesoporous TiO2-B nanobelts exhibit efficient H2 evolution capability, which is almost three times that of anatase TiO2 nanobelts.

We synthesized thiophene-based monomers (bis-EDOTs) with different ethylene glycol oligomer (EGO) lengths (TBO3, TBO4, and TBO5) and investigated their polymerization characteristics during photoelectrochemical polymerization (PEP) at the surfaces of dye (D205)-sensitized TiO2 nanocrystalline particles. During the PEP reaction, monomers were expected to diffuse toward neighboring dyes through the growing polymer layers to enable continuous chain growth. We found that the less bulky monomer (TBO3) formed a more compact polymer layer with a high molecular weight. Its diffusion to the active sites through the resulting growing polymer layer was, therefore, limited. We deployed layers of the polymers (PTBO3, PTBO4, and PTBO5) in iodine-free solid-state hybrid solar cells to investigate the lithium ion chelating properties of the polymers as a function of the number of oxygen atoms present in the EGOs. PTBO4 and PTBO5 were capable of chelating lithium ions, yielding a photovoltaic performance that was 142% of the performance obtained without the polymer layers (3.0→5.2%).