Search

Despite the unique ability of lanthanide-doped upconversion nanoparticles (UCNPs) to convert near-infrared (NIR) light to high-energy UV-vis radiation, low quantum efficiency has rendered their application unpractical in biomedical fields. Here, we report anatase titania-coated plasmonic gold nanorods decorated with UCNPs (Au NR@aTiO2@UCNPs) for combinational photothermal and photodynamic therapy to treat cancer. Our novel architecture employs the incorporation of an anatase titanium dioxide (aTiO2) photosensitizer as a spacer and exploits the localized surface plasmon resonance (LSPR) properties of the Au core. The LSPR-derived near-field enhancement induces a threefold boost of upconversion emissions, which are re-absorbed by neighboring aTiO2 and Au nanocomponents. Photocatalytic experiments strongly infer that LSPR-induced hot electrons are injected into the conduction band of aTiO2, generating reactive oxygen species. As phototherapeutic agents, our hybrid nanostructures show remarkable in vitro anticancer effect under NIR light [28.0% cancer cell viability against Au NR@aTiO2 (77.3%) and UCNP@aTiO2 (98.8%)] ascribed to the efficient radical formation and LSPR-induced heat generation, with cancer cell death primarily following an apoptotic pathway. In vivo animal studies further confirm the tumor suppression ability of Au NR@aTiO2@UCNPs through combinatorial photothermal and photodynamic effect. Our hybrid nanomaterials emerge as excellent multifunctional phototherapy agents, providing a valuable addition to light-triggered cancer treatments in deep tissue.

Graphitic porous carbons with combined two-dimensional layer crystallinity and porosity have shown great potential for energy storage. This report documents the design of ternary carbide (MAX)-derived carbon (MDC) from a MAX precursor with highly porous graphitic features, prepared through one-pot chlorination synthesis. The MDCs exhibited a peculiar discharge capacity pattern during long-term cycling, in which the discharge capacity decreased from 620 mA h g−1 (1st cycle) to 500 mA h g−1 (20th cycle) and then increased in proportion to the cycle number, reaching a value of ∼680 mA h g−1 (300th cycle) at 0.1C-rate. Even at high 0.5C-rate, the discharge cycling pattern was similar to that at 0.1C-rate, with a high reversible capacity of ∼650 mA h g−1 at the 500th cycle. Furthermore, despite applying two C-rate steps from 0.1C to 0.5C, an outstanding performance of ∼720 mA h g−1 at 0.1C-rate was observed at the 400th cycle, eclipsing the cycleability at a single 0.1 C-rate. In the MDCs, the order-to-disorder transformation in parts of the graphite upon prolonged cycling gave rise to defect structures consisting of many connected pores, which can facilitate Li-ion migration and increase the ion paths and storage sites.

Hybrid nanostructures are promising for ultrasound-triggered drug delivery and treatment, called sonotheranostics. Structures based on plasmonic nanoparticles for photothermal-induced microbubble inflation for ultrasound imaging exist. However, they have limited therapeutic applications because of short microbubble lifetimes and limited contrast. Photochemistry-based sonotheranostics is an attractive alternative, but building near-infrared (NIR)-responsive echogenic nanostructures for deep tissue applications is challenging because photolysis requires high-energy (UV-visible) photons. Here, we report a photochemistry-based echogenic nanoparticle for in situ NIR-controlled ultrasound imaging and ultrasound-mediated drug delivery. Our nanoparticle has an upconversion nanoparticle core and an organic shell carrying gas generator molecules and drugs. The core converts low-energy NIR photons into ultraviolet emission for photolysis of the gas generator. Carbon dioxide gases generated in the tumor-penetrated nanoparticle inflate into microbubbles for sonotheranostics. Using different NIR laser power allows dual-modal upconversion luminescence planar imaging and cross-sectional ultrasonography. Low-frequency (10 MHz) ultrasound stimulated microbubble collapse, releasing drugs deep inside the tumor through cavitation-induced transport. We believe that the photoechogenic inflatable hierarchical nanostructure approach introduced here can have broad applications for image-guided multimodal theranostics.

In recent years, metal halide perovskites (MHPs) have attracted attention as semiconductors that achieve desirable properties for optoelectronic devices. However, two challenges—instability and the regulated nature of Pb —remain to be addressed with commercial applications. The development of Pb-free halide double perovskite (HDP) materials has gained interest and attention as a result. This family offers potential in the field of optoelectronic devices through flexible material designs and compositional adjustments. We highlight recent progress and development in halide double perovskites and encompass the synthesis, optoelectronic properties, and engineering of the electronic structures of these materials along with their applications in optoelectronic devices. Computational and data-driven statistical methods can also be used to explore mechanisms and discover promising candidate double perovskites.

As strenuous research works approach the theoretical limits of the lithium-ion battery, the need to exploit more sustainable chemistries has emerged as a primary concern. The development of the lithium–sulfur (Li–S) battery offers an energy density of 2567 W h kg−1, reflecting an up to three to fivefold enhancement against the state-of-the-art Li-ion device. Solving the critical degradation of the metal anode and suppressing correlated side reactions in the Li–S cell represent, however, pivotal steps towards commercial consideration. In light of the unique Li–S electrochemistry, we examine herein the technical challenges of the lithium metal anode, including the dendritic lithium nucleation and growth during Li plating, and the stabilization of the solid electrolyte interphase (SEI). We revisit key contributions to establish a guideline of crucial factors determining the stability of the anode and its correlation with the electrolyte selection, electrode current density, and the effect of the shuttle of polysulfide intermediate species. Most importantly, our review delivers a comprehensive comparison of introduced strategies for the metal surface protection (including electrolyte-modification-based approaches and metal surface coating), along with a theoretical understanding and analysis of the underlying methodologies. This review sheds light on future opportunities towards a practical application of Li–S batteries, while stimulating progress in the exploitation of lithium metal anodes in parallel technologies in the development of energy storage for a sustainable future (266 citations).

We report a distinct method for the production of organic-inorganic hybrid perovskite (OIHP) nanostructures using block copolymer micelles as scaffolds. We reveal that various nanostructures can be obtained by controlling the parameters related to micelle disassembly. The strategy reported herein can be generalized for the fabrication of diverse nanostructures toward target-oriented potential applications.

Despite the ability to precisely tune their bandgap energies, mixed halide perovskites (MHPs) suffer from significant spectral instability, which obstructs their utilization for the rational design of light-emitting diodes. Here, we investigate the origin of the electroluminescence peak shifts in layered MHPs containing bromide and iodide. X-ray diffraction and steady-state absorption measurements prove effective integration of iodide into the cubic lattice and the spatially uniform distribution of halides in the ambient environment. However, the applied electric field during the device operation is found to drive the systematic halide migration. Quantum mechanical density functional theory calculations reveal that the different activation energies required for directional ion hopping lead to the redistribution of anions. In-depth analyses of the electroluminescence spectra indicate that the spectral shifting rate is dependent on the drift velocity of halides. Finally, it is suggested from our study that the dominant red emission is ascribed to the thermodynamically favorable selective hole injection. Our mechanistic study provides insights into the fundamental reason for the spectral instability of devices based on MHPs.

The colorimetric gas sensor offers an opportunity for the simple and rapid detection of toxic gaseous substances based on visually discernible changes in the color of the sensing material. In particular, the accurate detection of trace amounts of certain biomarkers in a patient's breath provides substantial clues regarding specific diseases, for example, hydrogen sulfide (H2S) for halitosis and ammonia (NH3) for kidney disorder. However, conventional colorimetric sensors often lack the sensitivity, selectivity, detection limit, and mass-productivity, impeding their commercialization. Herein, we report an inexpensive route for the meter-scale synthesis of a colorimetric sensor based on a composite nanofiber yarn that is chemically functionalized with an ionic liquid as an effective H2S adsorbent and lead acetate as a colorimetric dye. As an eye-readable and weavable sensing platform, the single-strand yarn exhibits enhanced sensitivity supported by its high surface area and well-developed porosity to detect the breath biomarker (1 ppm of H2S). Alternatively, the yarn loaded with lead iodide dyes could reversibly detect NH3 gas molecules in the ppm-level, demonstrating the facile extensibility. Finally, we demonstrated that the freestanding yarns could be sewn into patterned textiles for the fabrication of a wearable toxic gas alarm system with a visual output.

Catalysis with single-atom catalysts (SACs) exhibits outstanding reactivity and selectivity. However, fabrication of supports for the single atoms with structural versatility remains a challenge to...

We developed perovskite solar cells (PSCs) with a ZnO electron-transporting layer (ETL) of which the surface was passivated with methoxybenzoic acid self-assembled monolayers (SAMs). The self-assembled monolayer (SAM) simultaneously improved the photovoltaic performance and device stability. First, the methoxybenzoic acid, which is noncovalently bonded to the methylammonium of the perovskite layer, effectively induced dipole moments; in particular, 3,4,5-trimethoxybenzoic acid (TMBA) gave a larger workfunction shift of ZnO ETL compared with 4-methoxybenzoic acid (MBA) and 3,4-dimethoxybenzoic acid (DMBA) owing to its strong dipole moment and hydrogen-bonding between the methoxy group and ammonium. This effectively enhanced the built-in voltage of the perovskite solar cell (PSC) device, which resulted in an improved electron transfer from the active layer to the ETL and a higher open-circuit voltage. Secondly, the SAM layer controlled the wettability of the perovskite precursor solution on the ZnO ETL and significantly improved the crystalline properties of the perovskite layer. Moreover, the ZnO/SAM ETL remarkably increased the PSC device stability under ambient conditions by preventing the proton transfer reaction between the perovskite layer and the ZnO ETL. As a result, the TMBA-SAM based PSC device achieved a significantly enhanced efficiency of 13.75% compared to 1.44% for the bare ZnO with high long-term stability.

Two-dimensional (2D) inorganic nanomaterials have attracted enormous interest in diverse research areas because of their intriguing physicochemical properties. However, reliable method for the synthesis and composition manipulation of polycrystalline inorganic nanosheets (NSs) are still considered grand challenges. Here, we report a robust synthetic route for producing various kinds of inorganic porous NSs with desired multiple components and precise compositional stoichiometry by employing tunicin, i.e., cellulose extracted from earth-abundant marine invertebrate shell waste. Cellulose fibrils can be tightly immobilized on graphene oxide (GO) NSs to form stable tunicin-loaded GO NSs, which are used as a sacrificial template for homogeneous adsorption of diverse metal precursors. After a subsequent pyrolysis process, 2D metallic or metal oxide NSs are formed without any structural collapse. The rationally designed tunicin-loaded GO NS templating route paves a new path for the simple preparation of multicompositional inorganic NSs for broad applications, including chemical sensing and electrocatalysis.

A compact composite of reduced graphene oxide (RGO) and spherical activated carbon (sAC) was prepared by microwave irradiation reduction using water as the solvent after mixing RGO and sAC and is a promising electrode material for supercapacitors. The removal of the oxygen functional group in RGO and the distinct structure of compact RGO/sAC composites are confirmed by FT–IR, XRD and XPS analyses. The morphology of the composite exhibits homogeneous and thick coating with an RGO nanosheet on the surface of the sAC. This structure has high micropore volume and leads to enhanced electrochemical performance. Based on the specific capacitance from the cyclic voltammetry curves, while the physical mixing compound of RGO/sAC (PM–RGO/sAC) is only 120 F/g at a scan rate of 2 mV/s, the compact RGO/sAC compound (MI–RGO/sAC) is 166 F/g by microwave irradiation, which enhances the specific capacitance by approximately 138% compared to that of the PM–RGO/sAC. Therefore, the composite material of MI–RGO/sAC driven by microwave irradiation can facilitate fast ion transport in supercapacitors and is a good candidate for electrodes.

Harvesting low-energy photons by strategically exploiting the photocatalytic properties of plasmonic and upconversion nanocomponents is a promising route to improve solar energy utilization. Herein, a rationally designed 3D composite photoanode integrating NIR-responsive upconversion nanocrystals (UCNs) and visible-responsive plasmonic Au nanoparticles (NPs) into 3D TiO2 inverse opal nanostructures (Au/UCN/TiO2) has been shown to extend the solar energy utilization in the UV–vis–NIR range. The NIR-responsive properties of NaYF4:Yb3+-based UCNs doped with Er3+ or Tm3+ ions, and the effect of an alternating sequential introduction of UCN and Au, have been assessed. With an extended overlap between the emission of Er-UCN and the characteristic SPR band of Au, our ternary Au/Er-UCN/TiO2 hybrid nanostructure unveiled a notable 10-fold improvement in photocurrent density under UV–vis–NIR illumination compared with a pristine TiO2 reference. The Au incorporation was confirmed to play a key role in enhancing the ...

In this work, we developed the perovskite photodiodes based on the dimensionality-reduced quasi two-dimensional (Q-2D) photoactive layer structure by incorporating phenylethylammonium iodide (PEAI) into methylammonium lead iodide (MAPbI3), which effectively enhanced both the crystalline phase and the ambient stability of the perovskite. The Q-2D perovskite photodiode exhibited a dark current of 1.76 × 10−7 A/cm2, resulting in the detectivity (D*) of 2.20 × 1012 J and responsivity of 0.53 A/W, which is among the highest performance levels without the voltage bias (0 V) due to the systematically optimized perovskite phase resulting in the reduced leakage current. In addition, the current density of Q-2D perovskite photodiode maintained 76% of the initial level current density even after 80 days in the ambient condition, compared to 15% of 3D perovskite photodiode control sample. Such superior performance and stability were mainly attributed to the enhanced degree of crystallization of the Q-2D perovskites, which was confirmed by X-ray diffraction and grazing incidence wide-angle X-ray scattering (GIWAXS) measurement. Also, the improved stability of Q-2D perovskite films was confirmed by both lifetime test and atomic force microscopy studies where the negligible number of pinholes was observed in the quasi-2D perovskite films while considerable deformations were found in the 3D perovskites photodiode. Our study suggests a simple and robust protocol for the development of stable and high-performance perovskite photodetectors via dimensional and constitutional optimization of conventional perovskites for the practical usage of perovskite in the photodiode applications.

Owing to the Purcell effect, optical micro-structures can control the radiative decay of the quantum emitters in transition metal dichalcogenide (TMDC) media. However, conventional optical microstructures change the local density of optical states (LDOS) not only at the photoluminescence (PL) wavelength of the TMDC quantum emitters and but also at the pump wavelength simultaneously and thus cause an inevitable influence on the excitation conditions. We propose and experimentally demonstrate a reflective metallic metasurface for independently engineering the excitation and radiation of quantum emitters in the TMDC monolayer

Continuous monitoring of hydrogen sulfide (H2S) in human breath for early stage diagnosis of halitosis is of great significance for prevention of dental diseases. However, fabrication of a highly selective and sensitive H2S gas sensor material still remains a challenge, and direct analysis of real breath samples has not been properly attempted, to the best of our knowledge. To address the issue, herein, we introduce facile cofunctionalization of WO3 nanofibers with alkaline metal (Na) and noble metal (Pt) catalysts via the simple addition of sodium chloride (NaCl) and Pt nanoparticles (NPs), followed by electrospinning process. The Na-doping and Pt NPs decoration in WO3 grains induces the partial evolution of the Na2W4O13 phase, causing the buildup of Pt/Na2W4O13/WO3 multi-interface heterojunctions that selectively interacts with sulfur-containing species. As a result, we achieved the highest-ranked sensing performances, that is, response (Rair/Rgas) = 780 @ 1 ppm and selectivity (RH2S/REtOH) = 277 against 1 ppm ethanol, among the chemiresistor-based H2S sensors, owing to the synergistic chemical and electronic sensitization effects of the Pt NP/Na compound cocatalysts. The as-prepared sensing layer was proven to be practically effective for direct, and quantitative halitosis analysis based on the correlation (accuracy = 86.3%) between the H2S concentration measured using the direct breath signals obtained by our test device (80 cases) and gas chromatography. This study offers possibilities for direct, highly reliable and rapid detection of H2S in real human breath without the need of any collection or filtering equipment.

Conductive metal-organic frameworks (cMOFs) are emerging materials for various applications due to their high surface area, high porosity, and electrical conductivity. However, it is still challenging to develop cMOFs having high surface reactivity and durability. Here, highly active and stable cMOF are presented via the confinement of bimetallic nanoparticles (BNPs) in the pores of a 2D cMOF, where the confinement is guided by dipolar-interaction-induced site-specific nucleation. Heterogeneous metal precursors are bound to the pores of 2D cMOFs by dipolar interactions, and the subsequent reduction produces ultrasmall (≈1.54 nm) and well-dispersed PtRu NPs confined in the pores of the cMOF. PtRu-NP-decorated cMOFs exhibit significantly enhanced chemiresistive NO2 sensing performances, owing to the bimetallic synergies of PtRu NPs and the high surface area and porosity of cMOF. The approach paves the way for the synthesis of highly active and conductive porous materials via bimetallic and/or multimetallic NP loading.

Magnetic and spintronic media have offered fundamental scientific subjects and technological applications. Magneto-optic Kerr effect (MOKE) microscopy provides the most accessible platform to study the dynamics of spins, magnetic quasi-particles, and domain walls. However, in the research of nanoscale spin textures and state-of-the-art spintronic devices, optical techniques are generally restricted by the extremely weak magneto-optical activity and diffraction limit. Highly sophisticated, expensive electron microscopy and scanning probe methods thus have come to the forefront. Here, we show that extreme anti-reflection (EAR) dramatically improves the performance and functionality of MOKE microscopy. For 1-nm-thin Co film, we demonstrate a Kerr amplitude as large as 20° and magnetic domain imaging visibility of 0.47. Especially, EAR-enhanced MOKE microscopy enables real-time detection and statistical analysis of sub-wavelength magnetic domain reversals. Furthermore, we exploit enhanced magneto-optic birefringence and demonstrate analyser-free MOKE microscopy. The EAR technique is promising for optical investigations and applications of nanomagnetic systems., Magneto-optic Kerr effect microscopy is useful for dynamic magnetic studies, but is limited by the weak magneto-optical activity. Here, the authors show that extreme anti-reflection result in a Kerr amplitude as large as 20° and enables real-time detection of sub-wavelength magnetic domain reversals.

The interlayer exciton of van der Waals heterostructure has become a promising platform for realizing Bose-Einstein condensation and demonstrating novel excitonic devices. For increasing the critical temperature of bosonic condensation or long-range transport, the short lifetime of the interlayer excitons has to be improved by suppressing both the radiative and non-radiative recombination processes[1,2]. However, due to its out-of-plane electric dipole nature, the radiative recombination of the interlayer exciton has not yet been able to be suppressed with conventional optical approaches[3,4]. Here, we present a theoretical study on the reflective metasurface that can suppress the density of optical states for the out-of-plane dipole moment. The metasurface consists of Au nanodisks arranged in a square lattice on the Au substrate. We examined the out-of-plane dipole emitter inside the 20-nm-thick hexagonal-BN layer, which is placed on the flat surface of the 140-nm-thick SiO2 layer covering the Au disk array. We targeted the WSe2/MoSe2 interlayer exciton of which the radiation wavelength is 900 nm. Blocking the radiative decay channels of the dipole emitter to the horizontal directions as well as the vertical directions, the proposed metasurface strongly suppresses the Purcell factor down to ~0.011 at maximum (~0.018 on average), which corresponds to the enhancement of the radiative decay time as amount as ~91 times (~56 times).

The development of freestanding fiber-type chemiresistors, having high integration ability with various portable electronics including smart clothing systems, is highly demanding for the next-generation wearable sensing platforms. However, critical challenges stemming from the irreversible chemical sensing kinetics and weak reliability of the freestanding fiber-type chemiresistor hinder their practical use. In this work, for the first time, we report on the potential suitability of the freestanding and ultraporous reduced graphene oxide fiber functionalized with WO3 nanorods (porous WO3 NRs-RGO composite fiber) as a sensitive nitrogen dioxide (NO2) detector. By employing a tunicate cellulose nanofiber (TCNF), which is a unique animal-type cellulose, the numerous mesopores are formed on a wet-spun TCNF-GO composite fiber, unlike a bare GO fiber with dense surface structure. More interestingly, due to the superior wettability of TCNF, the aqueous tungsten precursor is uniformly adsorbed on an ultraporous TCNF-GO fiber, and subsequent heat treatment results in the thermal reduction of a TCNF-GO fiber and hierarchical growth of WO3 NRs perpendicular to the porous RGO fiber (porous WO3 NRs-RGO fiber). The freestanding porous WO3 NRs-RGO fiber shows a notable response to 1 ppm NO2. Furthermore, we successfully demonstrate reversible NO2 sensing characteristics of the porous WO3 NRs-RGO fiber, which is integrated on a wrist-type wearable sensing device.

Flexible and stretchable electrochromic supercapacitor systems are widely considered as promising multifunctional energy storage devices that eliminate the need for an external power source. Nevertheless, the performance of conventional designs deteriorates significantly as a result of electrode/electrolyte exposure to atmosphere as well as mechanical deformations for the case of flexible systems. In this study, we suggest an all-transparent stretchable electrochromic supercapacitor device with ultrastable performance, which consists of Au/Ag core–shell nanowire-embedded polydimethylsiloxane (PDMS), bistacked WO3 nanotube/PEDOT:PSS, and polyacrylamide (PAAm)-based hydrogel electrolyte. Au/Ag core–shell nanowire-embedded PDMS integrated with PAAm-based hydrogel electrolyte prevents Ag oxidation and dehydration while maintaining ionic and electrical conductivity at high voltage even after 16 days of exposure to ambient conditions and under application of mechanical strains in both tensile and bending condit...

Pt-based catalysts are suffering from the intrinsic high cost and poor stability for practical use in fuel cells. We develop a free-standing fabric type Pt-free high-performance oxygen reduction reaction (ORR) catalyst, consisting of N, Fe-codoped carbon nanofibers and graphene (N/Fe-CG) hybrids. Electrospinning is used to synthesize the free-standing fabric catalysts. Incorporation of graphene into the nanofiber structure greatly increases the electrical conductivity and catalytic surface area. X-ray photoelectron spectroscopy (XPS) analysis provides evidence that Fe-N4 active centers are possibly formed in the catalyst, as is confirmed by electrochemical tests also. Compared to commercial Pt/C, our N/Fe-CG exhibits a similar level of catalytic activity but superior stability and methanol tolerance in both alkaline and acidic media, making it a good candidate for an ORR electrocatalyst in energy storage/conversion and other relevant applications.

In the development of water splitting technologies, the design of hybrid architectures incorporating multiple phases which provide active centers with precise functionalities is a promising strategy. Herein, we report the design of Ni- and Ru-based electrocatalysts within a wide Ni/Ru ratio range, prepared through a one-step heat treatment of ultra-thin ruthenate nanosheets and NiCl2·6H2O and NaH2PO2·H2O precursors. At 250 °C under an argon flow, a pristine Ru electrode was shown to undergo preferential ruthenate-to-metallic Ru phase transformation, revealing preferable hydrogen evolution reaction (HER) fingerprints. At low Ni/Ru ratios, the interaction between the Ni2+ ions and the negatively charged ruthenate favored the in situ growth of highly dispersed surface Ni-based moieties below 5 nm in diameter. XPS measurements confirmed, however, that these narrow moieties were swiftly oxidized to NiO, whereas larger Ni-based agglomerates at higher Ni/Ru ratios were less prone to oxidation. This size-dependent propensity of Ni2P moieties toward oxidation, reported here for the first time, agrees with the surface oxidation of Ni2P nanoparticles (50–100 nm) to a limited extent. At Ni/Ru = 0.36, the incorporated NiO favored a synergistically superior oxygen evolution reaction (OER) performance and an optimal 1.7-fold activity enhancement at limiting current densities. An antagonistic effect in the HER performance of these hybrid materials was, nonetheless, simultaneously observed and ascribed to the blockage of the active Ru surface. While the performance of these nano-architectures remains a modest addition to the current state-of-the-art of water splitting platforms in alkaline electrolyte media, our results primarily reveal representative bottlenecks in the integration of multiple phases during synthesis steps and the effects of arising between integrated components on the catalytic behavior of resulting hybrids.

Multi-heterogeneous oxide sensing layers, i.e., NiO/Fe2O3 catalyst loaded SnO2 fiber-in-tube nanostructures (NiO/Fe2O3-FITs), were rationally synthesized from an electrospinning solution containing a bio-inspired chitosan-bimetal complex template. The NiO/Fe2O3-FITs showed remarkably enhanced sensing properties and superior cross-sensitivity toward sub-ppm levels of formaldehyde.

The atmospheric pressure plasma jet (APPJ) has a merit to treat curved or 3D surface without using a ground electrode but nonetheless limits applications for expanding treatment area due to the localized ionization energy induced by the propagation along the direction of guided ionization waves. This paper proposes a uniform area treatment for surface modification based on the experimental case studies relative to variations of the APPJ structures, such as the number of array jets and guide-tube, including bluff-body (GB) system plus gas compositions. In these case studies, the current, infrared (IR), and optical emission spectrum (OES) are analyzed to investigate the factors affecting intensive glow-like plasma generation for uniform area treatment. Plasma-treated polyethylene terephtalate (PET) films are additionally examined to check the possibility of uniform area treatment for surface modification by using atomic force microscope (AFM), Fourier transform-infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and water contact angle (WCA). Only in case of three-array jets with GB system using Ar with O2 gas, the intense glow-like plasma is observed to be produced widely in discharge space, thereby enabling the entire surface of PET films to be treated uniformly. In particular, the proposed APPJs are observed to generate more abundantly the reactive nitrogen species (RNS) ranging from 330 and 380 nm and the reactive oxygen species (ROS) at 777.4 and 844.6 nm. Furthermore, the plasma-treated PET film shows that the abundant RNS and ROS play a significant role in smoothening and changing its surface into hydrophilic surface. As a result, it is confirmed that the intense glow-like plasma generated broadly by the proposed APPJs can uniformly treat the entire surface of PET films.

2D black phosphorus (BP) and MXenes have triggered enormous research interest in catalysis, energy storage, and chemical sensing. Unfortunately, the low stability of these materials under practical operating conditions remains a critical bottleneck, particularly as they are prone to oxidization under moisture. In this work, the design and application of stable 2D heterostructures obtained from decorating BP and MXene (Ti3 C2 Tx ) with few-layer holey graphene oxide (FHGO) membranes are presented. In the resulting heterostructured systems, FHGO serves as a multifunctional passivation layer that shields BP or MXene from oxidative degradation, while allowing the selective diffusion of target gas molecules through its micropores and toward the underlying 2D material. Through a case study of dilute NO2 sensing, it is demonstrated that these heterostructures show a greatly enhanced sensing performance under humid conditions, where fast sensing speed and response are consistently observed, and high stability is impressively retained upon repetitive sensing cycles for 1000 min. These results corroborate the efficacy of material decoration with porous FHGO membranes and suggest that this is a generalizable strategy for reliable high-performance applications of 2D materials.

In article number https://doi.org/10.1002/advs.201903318, Il‐Doo Kim, Sung‐Yool Choi, and co‐workers propose a low‐thermal‐budget and ambient‐air process for simultaneous heteroatom doping and reduction of graphene oxide (GO) through the synthesis of B‐doped reduced GO by single‐shot irradiation with intense pulsed light. The resultant B‐doped reduced GO features improved NO2 sensing performance over pristine reduced GO, especially in controlled humidity.

This paper investigated the chemical bonding features and conductivity characteristics of atmospheric pressure plasma (APP) conducting polymerized polypyrrole (pPPy) by iodine (I2) doping method in...

Organic-inorganic hybrid perovskites are ideal materials for photodetection owing to their high charge carrier mobility, long charge carrier diffusion length, low dark current density and sharp absorption edge. However, a relatively small band gap (1.6 eV) limits their photon-harvesting efficiency in the near-infrared region. In the present work, we demonstrate a hybrid methylamine iodide and Pb-Sn binary perovskite as the light absorption layer in photodetectors. Experimentally, the wavelength of photoresponse onset for the photodetectors can be extended to as great as 1,000 nm when the Sn content of the hybrid perovskite is increased to 30 mol%. In addition, the photodetectors exhibit a photoresponsivity of 0.39 A W−1, a specific detectivity of 7×1012 Jones, a fast photoresponse with rise and decay time constants and an external quantum efficiency greater than 50% in the wavelength range of 350–900 nm, with a maximum value of about 80% at 550 nm.

Developing photocatalysts with effective charge separation and fast surface reaction kinetics is crucial to realizing efficient photocatalytic water splitting. In this study, we report a strongly coupled two-dimensional-ternary-heterostructured photocatalyst by sequentially introducing reduced graphene oxide (rGO) and NiFe-layered double hydroxide (NiFe-LDH) on the surface of lanthanum titanate (LTO) via a facile hydrothermal and electrostatic self-assembly methodology, respectively. The synthesized 2D-rGO/LTO/NiFe-LDH photocatalyst showed remarkable photocatalytic H2 evolution activity under simulated light irradiation, even without expensive Pt cocatalyst. The enhancement of photocatalytic activity could be attributed to the efficient interfacial charge transfer at the rGO/LTO heterojunction interface, and the enhanced hole (h+) trapping ability of NiFe-LDH cocatalyst at the LTO/NiFe-LDH interface, respectively. These attributes could effectively enlarge the life time of photo-generated electron-hole pairs, and increase the electron density for hydrogen production. The optimal rGO/LTO/NiFe-LDH nanocomposite remain sustained even after four successive experimental runs, without apparent change in the H2 evolution rate. The present work elucidates a new strategy to maximize the efficiency via synergetic effect of incorporating rGO and NiFe-LDH as dual cocatalysts, and shows a feasible strategy of using earth-abundant materials as cocatalysts to enhance the overall photocatalytic water splitting reactions.

In recent years, the concept of combined therapy using gold hybrid nanomaterials has been broadly adopted to pioneer new anticancer treatments. However, their synergistic anticancer effects have yet to be thoroughly investigated. Herein,a hybrid gold nanobipyramid nanostructure coated with molybdenum disulfide (MoS2) semiconductor (AuNBPs@MoS2) was proposed as a smart nanozyme for anticancer therapy and two-photon bioimaging. The hybrid material showed dramatically enhanced localized surface plasmon resonance property under excitation owing to its anisotropic nature, coupled with the rich electron density in MoS2, resulting in the superior in situ photogeneration of reactive oxidative species (ROS - 1O2, •OH). We demonstrated that the synergistic effect of enhanced photothermal conversion and generation of ROS could increase the anticancer effect of AuNBPs@MoS2. Two-photon luminescence imaging confirmed that AuNBPs@MoS2 was successfully internalized in cancer cells and that simultaneous anticancer treatments based on catalytic and photothermal therapy could be achieved. This study highlighted, for the first time, a novel approach of plasmon-mediated powerful anticancer therapy and imaging via the unprecedented combination of anisotropic AuNBPs and two-dimensional MoS2 material.

Extraordinary light–matter interaction on the surface of metallic nanostructures can excite surface plasmons (SPs), followed by generation of charge carriers with high energy, that is, “hot electrons and holes”, via nonradiative decay. Such plasmonic hot carriers are potentially useful for photocatalysis, electrocatalysis, photovoltaics, optoelectronics, and theragnosis since hot carrier transfer to the desired substrate can accelerate specific redox reactions or facilitate electrical benefits on devices. In this regard, there is a growing interest in the detection and visualization of hot carriers at the location where plasmonic hot carriers are practically generated and transferred by means of conventional or newly developed procedures, as summarized in Table 1 of the main paper. Although direct imaging of plasmonic hot carriers or pathways are still challenging due to ultrafast dynamics of plasmonic hot carriers, state-of-the-art microscopic approaches have successfully demonstrated the mapping of the ...

Semiconducting metal oxides (SMOs) based gas sensors are inherently hampered by requirement of high working temperature because of their wide bandgaps. Consequently, there are remain challenges to utilize SMOs based gas sensors with regard to continuous gas monitoring platform with low power consumption. To address the inherent limitation, nitridation (i.e., N doping) of WO3 NFs to WOxNy NFs was herein introduced for realization of low-temperature NO2 sensing. Importantly, nitridation was conducted at intervals of 50 °C from 400 to 600 °C to adjust the degree of phase transition from semiconducting WO3 to conductive WON phases. To further optimize the conductivity and improve the sensing characteristics, i.e., reduction of optimal operating temperature and enhancement of sensitivity, WOxNy NFs were functionalized with platinum (Pt) catalytic nanoparticles (NPs) by physical mixing. Pt NPs functionalized WOxNy NFs nitrided at 550 °C exhibited improved normalized resistance change and superior selectivity against C2H5OH, C7H8, CH4, CO, NH3, and NO at 50 °C. The noble metal catalyst–metal oxynitride hybrid system is suggested as an effective NO2 sensing platform for low-temperature chemical sensor.

Carbon nanofibers (CNFs) are used as active materials for electrodes in various energy devices, such as lithium ion secondary batteries, supercapacitors, and fuel cells. Recent studies have shown that nanoscale coatings on carbon nanotubes increase the output and lifespan of these devices owing to the improvement of their mechanical and chemical properties. Among various coating methods, atomic layer deposition (ALD) can adjust the thickness of the coating layer conformally without any directional growth. Therefore, ALD can coat particles with high aspect ratios, such as CNFs, even at nanometer levels of thickness. In this work, we grew two different morphologies of a SnO2 layer on CNF. We used two types of ALD equipment: flow-type ALD (static ALD), and fluidized bed reactor-type ALD (dynamic ALD). Static ALD could form a discontinuous SnO2, while a uniform SnO2 layer was formed by pre-inserting a layer of Al2O3. On the other hand, dynamic ALD formed a uniform SnO2 layer without pre-insertion of an Al2O3 layer. X-ray photoelectron spectroscopy analysis revealed that both Sn4+ and Sn2+ were present in SnO2 on the CNF deposited by static ALD, probably due to the formation of an interfacial layer between the SnO2 and CNF. When the dynamic ALD method was used, only Sn4+ was present in the SnO2 on CNF. Cyclic voltammetry analysis was performed to characterize the electrochemical properties of the SnO2-coated CNF as an electrode on a direct methanol fuel cell. It was revealed that the discontinuous SnO2 on CNF deposited by static ALD showed the highest current efficiency as well as enhanced electrocatalytic stability.

The development of high-performance near-infrared (NIR) photocatalysts with long-term stability and the elucidation on the working mechanism along with multifunctional activity toward biomedical ap...

The α-clusterization of an atomic nucleus has been studied for a long time, even from the earliest days of nuclear physics. Our understanding of the α-cluster structure is, however, mainly limited to the self-conjugate A = 4n (n = 2, 3, 4, · · · ) light nuclei and some of the neutron-rich radionuclides such as 10Be, 11B, and 14C. In order to study the α-cluster structure of a neutron-deficient 22Mg nucleus, we have measured the 18Ne(α, α)18Ne scattering in inverse kinematics by using radioactive 18Ne beams and the 4He gas target at the Center for Nuclear Study radioactive ion beam separator of the University of Tokyo. Recoiling α particles from the scattering were detected by using silicon strip detectors, which constitute ΔE-E telescopes for particle identification. By adopting a thick target method, we were able to investigate a wide range of excitation energies Ex = 9.9 - 16.5 MeV in 22Mg in this work.

The 25 mol% K2O-added K(Sr2Na)Nb4O13 ceramic sintered at 1275 °C exhibited a pure and dense K(Sr2Na)Nb4O13 phase, which had four octahedral layers. Synthesis of a pure K(Sr2Na)Nb4O13 ceramic was not possible without excess K2O, due to the formation of a Na-deficient K(Sr2Na2)Nb5O16 secondary phase, because of K2O evaporation during sintering. The dielectric constant (er) of the K(Sr2Na)Nb4O13 ceramic was 43.8 at 100 kHz, two times higher compared to the KSr2Nb3O10 ceramic, which has three octahedral layers. The increased er can be explained by the increased number of octahedral layers. Some of the Sr2+ ions in K(Sr2Na)Nb4O13 ceramic were replaced by Ba2+ ions, which have high ionic polarizability, to further increase er. The 25 mol% K2O-excess K(Sr0.8Ba0.2)2NaNb4O13 ceramic sintered at 1250 °C showed a high er of 67.4 at 100 kHz, which can be explained by the increased dipole moments and distortion of the NbO6 octahedra.

The temperature-dependent electrical properties of Au/GaN Schottky diodes with an Al2O3 layer prepared by using atomic layer deposition (ALD) were investigated. Compared to the Au/GaN junction, the Au/Al2O3/GaN junction was found to have lower barrier heights and higher ideality factors. For the Au/GaN junction, the native oxide and the thin surface barrier formed by surface states caused a large leakage current and a small capacitance. Due to surface passivation through the ALD process, the leakage current for the Au/Al2O3/GaN junction was reduced. The barrier height reduction for the Au/Al2O3/GaN junction was associated with interface dipole formation at the Al2O3/GaN interface.

Metal–organic frameworks (MOFs) are used as a new intriguing class of templates, which enable the creation of porous inorganic nanostructures via calcination. In this work, we first introduce in situ coupling of multidimensional MOFs for producing heterogeneous metal-oxide composite with multiple p–n junctions. Controlling relative ratios of two mixed solvents (water and ethanol), in zeolitic imidazolate framework (ZIF) growth, leads to the distinctive morphological evolution such as rod, sheet, and polyhedron particles. One-pot hybridization of ZIF-8 (sheet) with ZIF-67 (rods) results in the generation of hierarchically assembled 1D ZIF-67 rods anchored on a 2D ZIF-8 sheet. Through the calcination of such hybridized ZIFs, we successfully prepared hierarchically assembled 1D Co3O4 rods immobilized in a 2D ZnO sheet, possessing numerous n-type ZnO/p-type Co3O4 heterogeneous interfaces. This unique structure offers a remarkably enhanced chemiresistive sensing performance (Ra/Rg = 29 at 5 ppm acetone)., The hybridization of ZIF nanorod with ZIF nanosheet offers great potential for producing hierarchically assembled heterogeneous metal oxides, which are mostly suitable for chemiresistive gas sensors.

Bimodally meso- (2–50 nm) and macroporous (>50 nm) WO3 microbelts (MBs) functionalized with sub-3 nm Pt catalysts were fabricated via the electrospinning technique followed by subsequent calcination. Importantly, apoferritin (Apo), tea saponin and polystyrene colloid spheres (750 nm) dispersed in an electrospinning solution acted as forming agents for producing meso- and macropores on WO3 MBs during calcination. Particularly, mesopores provide not only numerous reaction sites for effective chemical reactions, but also facilitate gas diffusion into the interior of the WO3 MBs, dominated by Knudsen diffusion. The macropores further accelerate gas permeability in the interior and on the exterior of the WO3 MBs. In addition, Pt nanoparticles with mean diameters of 2.27 nm were synthesized by using biological protein cages, such as Apo, to further enhance the gas sensing performance. Bimodally porous WO3 MBs functionalized by Pt catalysts showed remarkably high hydrogen sulfide (H2S) response (Rair/Rgas = 61 @...

The incorporation of plasmonic properties recently emerged as an advanced strategy for achieving high-performance catalysis. The hot carriers and near-field enhancement induced by localized surface plasmon resonance (LSPR) excitation are the key parameters that are responsible for the enhanced performance. Thus, the logical combination of the plasmonic nanostructures and electrocatalytic materials can be an effective strategy for further widening application of the plasmonic effect. This short Review provides a concise overview of the fundamental principles of LSPR; the mechanism of plasmon-enhanced electrocatalysis; alternative design methods of plasmonic nanomaterials for various catalytic systems; and recent progress in plasmon-mediated electrocatalysis for the production of energy, including electrochemical conversion of different feedstocks into fuels along with fuel cell catalysis. This Review also sheds light on the areas where major advancements are required to further improve the field of plasmon...

An Al2O3/AlN bilayer deposited on GaN by atomic layer deposition (ALD) is employed to prepare Al2O3/AlN/GaN metal-insulator-semiconductor (MIS) diodes, and their interfacial properties are investigated using X-ray photoelectron spectroscopy (XPS) with sputter etch treatment and current-voltage (I-V) measurements. XPS analyses reveal that the native oxides on the GaN surface are reduced significantly during the early ALD stage, indicating that AlN deposition effectively clelans up the GaN surface. In addition, the suppression of Al-OH bonds is observed through the ALD process. This result may be related to the improved device performance because Al-OH bonds act as interface defects. Finally, temperature dependent I-V analyses show that the barrier height increases and the ideality factor decreases with an increase in temperature, which is associated with the barrier inhomogeneity. A Modified Richardson plot produces the Richardson constant of A** as 30.45 Acm−2K−2, which is similar to the theoretical value of 26.4 Acm−2K−2 for n-GaN. This indicates that the barrier inhomogeneity appropriately explains the forward current transport across the Au/Al2O3/AlN/GaN interface.

In recent years, the electroreduction of CO2 to valuable products has emerged as a rational answer to rising CO2 emissions and a strategic approach to incorporate renewable electricity from intermittent sources (e.g., wind and solar) into the global energy supply. The reduction of CO2 to CO has been highlighted in the widely explored industrial conversion of syngas (CO and H2) to fuels. Herein, we report a promising electrocatalyst incorporating well-dispersed gold nanoparticles (Au NPs) on ultrathin titanate nanosheets (TiNS). By tuning the contents of Au (in the ranges of 0 to 93 wt % Au) in the hybrid Au/TiNS architecture, CO product selectivity was effectively controlled (in the range of CO Faradaic efficiency from 3 to over 80%) with the sole additional formation of H2, which is of pronounced industrial interest. Most importantly, a control of both component amounts was suggested to result in a variation of corresponding electronic properties based on the interaction between Au NP and TiNS substrate,...

Although single-nozzle electrospraying seems a versatile technique in the synthesis of spherical semiconducting metal oxide structures, the synthesized structures find limited use in gas-sensing applications because of their thick and dense morphology, which minimizes the accessibility of their inner surfaces. Herein, unprecedented spherical SiO2@SnO2 core–shell structures are synthesized upon calcination of single-nozzle as-electrosprayed spheres (SPs) containing tin (Sn) and silicon (Si) precursors. Subsequent etching of SiO2 in NaOH (pH 12) affords meso/macroporous SnO2 hollow spheres (HSPs) with short diffusion length (31.4 ± 3.1 nm), small crystallites (15.5 nm), and large Brunauer–Emmett–Teller surface area (124.8 m2 g–1). Apart from surface meso/macropores, diffusion of gases into porous SnO2 sensing layers is realized through inner interconnection of voids of the SnO2 HSPs into a three-dimensional network. Functionalization of the postetched SnO2 HSPs with platinum (Pt) nanoparticles at 0.08 wt % ...

Electrospun WO 3 nanofibers (NFs) with hierarchically interconnected porosity (HP_WO 3 NFs) are designed by using dual sacrificial templates including zero-dimensional (0D) polystyrene (PS) colloids and one-dimensional (1D) multi-walled carbon nanotubes (MWCNTs). Multi-dimensionally interconnected pore-loaded structures offer much enhanced surface area and abundant gas penetration pathway into the inner sensing layers, which are essential requirements for effective gas adsorption-desorption reactions, fast gas diffusion, and high gas response. Moreover, such porous WO 3 NFs are homogeneously decorated by Pt nanoparticles (Apo-Pt) encapsulated in a protein nanocage, i.e., apoferritin, which enables uniform catalyst sensitization in interior and exterior of highly gas accessible NFs. The HP_WO 3 NFs sensitized by Apo-Pt (Apo-Pt@HP_WO 3 NFs) exhibited highly selective and sensitive acetone response (R air /R gas = 10.80 ± 0.06 @ 1 ppm) under high humidity atmosphere (90% RH). To investigate the potential suitability as exhaled breath analyzers, we tested three sensor arrays consisting of mesoporous WO 3 NFs templated by MWCNTs (MP_WO 3 NFs), HP_WO 3 NFs, and Apo-Pt@HP_WO 3 NFs. The result revealed that targeted acetone molecules were clearly classified against six different interfering molecules (H 2 S, C 7 H 8 , C 2 H 5 OH, CO, NH 3 and CH 4 ) through principle component analysis (PCA), confirming excellent acetone selectivity of the designed sensor arrays.

This article has analyzed conducting polymer from the viewpoint of material properties, which is polymerized under atmospheric pressure condition for coupling and remote conditions, respectively. T...

This work presents a deposition of carbon thin films on the substrate from sucrose-containing-carbon source, that is, sugar, by using the two different plasma processes; one process is that the car...