Water scarcity remains a critical global challenge, driving the need for efficient technologies that can capture water directly from the atmosphere. Among various adsorbents, metal-organic frameworks (MOFs) have shown great promise for water capture owing to their tunable pore structures and chemical functionalities. In this work, a linker functionalization strategy incorporating embedded hydrophilic atoms was employed to design a new MOF, LMRC-2 (LMRC = Lanzhou Magnetic Resonance Center). LMRC-2 exhibits over a 10-fold increase in water uptake at low relative humidity (RH) compared to that of its hydrophobic parent MOF, while maintaining a comparable total capacity at high RH. Solid-state NMR spectroscopy provided direct evidence that the pyrrolic nitrogen atoms in the linker act as strong water adsorption sites. These results highlight the effectiveness of rational linker modification for tuning the hydrophilicity of MOFs and demonstrate that solid-state NMR can be a powerful probe for elucidating water adsorption mechanisms in porous materials.

Photochemical vapor generation (PVG) offers a green and efficient alternative for sample introduction in atomic spectrometry; however, its efficiency in low-acidity media remains limited due to the lack of effective sensitizers. In this work, we report the application of a single-atom catalyst (SAC) in highly efficient PVG of osmium (Os) in highly dilute formic acid medium (0.001 M). Specifically, a cadmium single-atom catalyst anchored on a porphyrin-based covalent organic framework (Cd-COF) was synthesized via a rapid dielectric barrier discharge (DBD) strategy followed by wet impregnation. The isolated Cd sites exhibit excellent stability and photocatalytic activity under mild and low-acid conditions, achieving a limit of detection (LOD) of 0.20 ng L-1 for Os by inductively coupled plasma mass spectrometry (ICP-MS). Notably, a ∼30-fold signal enhancement over the acid-only system was achieved under these mild conditions. The practicality of this method was validated through the successful analysis of environmental water samples. Mechanistic investigations reveal that the atomically dispersed Cd sites promote efficient charge separation and facilitate dual redox pathways, enabling the formation of volatile Os-containing species. This work validates the feasibility of single-atom catalysts for trace Os PVG and demonstrates their potential for developing environmentally friendly and ultrasensitive PVG platforms for trace element analysis by atomic spectrometry.

Atomic fluorescence spectrometry (AFS) has become a widely used method for determining inorganic elements. However, improving the sensitivity and selectivity of AFS detection for trace or ultratrace elements is a major bottleneck. In this work, a single cobalt site catalyst anchored on a ketoenamine-based covalent organic framework (Co-COF) was developed and first utilized as a simultaneous adsorbent and photocatalyst for the determination of Bi3+ by photochemical vapor generation-atomic fluorescence spectrometry (PVG-AFS). The interference from coexisting hydride-forming elements and transition metal ions was greatly reduced after the matrix separation with Co-COF. Under the selected experimental conditions, the analytical sensitivity for bismuth by PVG-AFS was largely improved, and the limit of detection (LOD) was reduced to 0.009 μg L-1. The method accuracy was validated by successful determination of bismuth in natural water samples and soil-certified reference materials. This work unveils the great potential of single-atom catalysts in PVG and opens a new avenue for sample introduction in atomic spectrometry.

A Yb:YAG single-crystal rod (SCR) with great optical properties was successfully grown based on the laser-heated pedestal growth (LHPG) method, and its laser characteristics were comprehensively studied. Pumped by a 940 nm laser diode, the output power of the continuous-wave (CW) laser was 3.72 W, corresponding to a slope efficiency of 44.3%. The continuous tuning range of the Yb:YAG SCR was 22 nm. In addition, a semiconductor saturable absorber mirror (SESAM) was used to realize the passively mode-locked Yb:YAG SCR laser. Operating at 1049.5 nm, the laser oscillator had a 1.6 ps pulse width with a repetition rate of 54.5 MHz.

We reported an intra-cavity pumped Q-switched laser with dual-wavelength synchronous output at 2066.7 nm and 1940nm. Ho:YLF crystal was pumped by a self-Q-switched Tm:YAP laser, which was served as both a gain medium and a saturable absorber simultaneously. For Ho:YLF laser, under 11.4-W incident pump power, a stable pulse laser was achieved at 2066.7 nm with the highest peak power of 69.65 W and the pulse repetition rate of 42.14 kHz. Under the same incident pump power, the highest peak power and pulse repetition rate of Tm:YAP laser were 17.85 W and 50.82 kHz, corresponding to the central wavelength of 1940nm. These results suggested that Q-switching without additional absorber element were effective way to obtain high-efficiency and compact 2.1 µm pulsed laser.

Highly efficient single-atom catalysts (SACs) hold great potential for promoting peroxymonosulfate (PMS) activation to facilitate organic pollutant degradation but precisely regulating and enhancing their catalytic efficiency remains a challenge. Here, single Cu atom catalysts anchored on a series of ketoenamine-based covalent organic frameworks (COFs) were developed as PMS activators via a facile dielectric barrier discharge (DBD) plasma and wet chemical method. Based on the systematic engineering of photoelectric structures at the molecular level, the charge distribution was precisely regulated by introducing different functional groups (Cu@TpPa-X, where X= -(CH3)2, -H, -CN). Among the obtained materials, Cu@TpPa-(CH3)2 possesses the best photocatalytic capability, and the mineralization (90%) of carbamazepine (CBZ) and the reaction rate constant (0.322 min-1) are comparable to those of the most advanced photocatalysts. Experiments and calculations demonstrate that the introduction of individual metal atoms increases the electron density at the active centre, and electron-donating groups accelerate the transfer of photogenerated carriers and improve the PMS adsorption to the material, which significantly improves the overall oxidation and mineralization kinetics. This work pioneers a novel approach for tailoring high-efficiency COF-based SACs, thus broadening their potential applications in photocatalysis. Introducing single Cu atoms and electron-donating groups onto ketoenamine-based covalent organic frameworks effectively regulates the local electron density and adsorption energy, thus significantly enhancing Fenton-like photo-oxidation performance.

It remains crucial but challenging to construct single-atom photocatalysts based on covalent organic framework (COF) materials in a simple, fast, and controllable manner and to clarify their structure-efficacy relationship. Here, a single-atom photocatalyst (Ni-TpBpy) featuring atomically dispersed Ni sites with a high loading content and a specific tetra-coordinated N2-Ni-Cl2 environment in a bipyridine-based COF was for the first time rapidly synthesized using dielectric barrier discharge (DBD) plasma and a wet chemical method. Visible light-driven Ni-TpBpy can achieve 97.8% photodegradation efficiency of acetaminophen at 0.177 min-1 in 30 min, outperforming other advanced photocatalysts. Experimental studies and density-functional theory (DFT) calculation clarified the role of well-dispersed Ni active sites in enhanced photodegradation, which not only narrowed the bandgap, facilitating carrier separation and migration, but also promoted the generation of reactive superoxide radicals. This study represents the first use of single-atom Ni-TpBpy in the efficient photocatalytic degradation of emerging pollutants with remarkable stability and universality, bringing new insights into the application of COF-based single-atom materials in environmental remediation.

Objective Bragg fibers have multiple unique optical properties such as photonic bandgap light guides, single -mode transmission over a wide frequency range, dispersion management, and low transmission loss, which make them attractive for broad applications. The transmission ability of a traditional hollow Bragg fiber is restricted by air -core collapse and structured -cladding deformation during optical fiber preparation. Even under tiny fiber cladding deformations, the bandgap can be violently degraded. All solid-state structures have been proven to solve the core collapse and cladding deformation problems of hollow Bragg fibers. Therefore, an urgent requirement exists to develop novel fiber structures and effective fiber fabrication methods to improve fiber transmission capability. In this study, an all -solid Bragg fiber with a chalcogenide glass core is fabricated via a compensated -stacking extrusion technique to address the challenge of hollow -core deformation in traditional Bragg fibers. The fiber consists of three pairs of uniform periodic cladding and low -loss windows in the range of 4-10 p.m. This experimental data can assist further study regarding mid -infrared bandgap-controlled fibers and unlock new directions for the development of high -quality laser transmissions or optical sensors in the mid -infrared region.Methods In this study, we first establish a theoretical model for all -solid-state Bragg fibers. Mid -infrared chalcogenide glasses Ge20As20Se15Te45and As2S3are chosen as high- and low -refractive -index cladding materials. The large difference in the refractive index between the alternating -layer materials helps to form the widest photonic bandgap. Two groups of fibers based on equal- or compensated -thickness glass are prepared for comparison. The cross sections, transmission loss values, and near -field energy distributions of these optical fiber types are calculated and analyzed.Results and Discussions According to the simulation results, the optimal structural parameters of all solid-state chalcogenide Bragg fibers are obtained. The experimental results show that optimized stacking extrusion based on compensated -thickness glass is the simplest and most effective method for improving fiber structural uniformity. The cross -sections of the all -solid Bragg fiber based on equal -thickness glass [Figs. 7(a)-(c)] show that the core and innermost cladding are irregularly elliptical, with a large difference in the thickness of the three pairs of periodic claddings. The thickness of the layers ranges from 10 p.m to 600 p.m, which significantly differs the simulation results [Fig. 8(a)]. The fiber cross -sections based on thickness -compensated glass [Figs. 7(d)-(f)] show that the fiber structure is highly circular, without deformation, and no obvious defects such as bubbles or holes are observed at the interfaces of adjacent layers. Three pairs of periodic claddings have similar thicknesses in a 6 -meter -long fiber, and the average ratio of each layer thickness to the fiber diameter is approximately 3:100 for an entire fiber length with 6 m length [Fig. 8(b)]. It is proven experimentally that it is feasible to solve the problem of uneven claddings and deformational cores using thickness -compensated glass. The average loss of fibers based on equal -thickness glass is 4 dB/m-6 dB/m, however, the uneven fiber structure results in light propagation in the cladding [Fig. 9(a)]. The fiber based on thickness compensated glass has four low loss windows [Fig. 9(b)]. For good light transmission effect, the light is confined in the core and almost no energy leaks into the cladding. Conclusions Bragg fibers based on the principle of effective omnidirectional reflection achieve high -power transmission at specific wavelengths by tuning the structural parameters of the claddings; however, some problems remain. In this study, an all -solid-state Bragg fiber with a chalcogenide glass core is fabricated using a compensated stacking extrusion technique to solve the problem of hollow core deformation in traditional Bragg fibers. Ge20As20Se15Te45 and As2S3 glasses are doped as high- and low -refractive -index cladding materials, respectively, and an all -solid-state chalcogenide glass Bragg fiber with three pairs of periodic cladding layers is successfully fabricated via compensated stacking extrusion. The superior structural uniformity of the prepared chalcogenide Bragg fibers is verified by comparing the cross -sections of the front, middle, and end of the Bragg fibers. Three pairs of periodic claddings have similar thicknesses in a 6 -meter -long fiber, and the average ratio of each layer thickness to the fiber diameter is approximately 3:100 for an entire fiber with length of 6 m. The light spot pattern proves that the optical fiber has good light transmission ability.It is proven experimentally that it is feasible to prepare chalcogenide Bragg fibers using the extrusion method. In future, our research will further improve the extrusion mold and conditions aiming to develop higher performance photonic crystal fibers based on chalcogenide glass.

Fluorescence-based chemical sensors have garnered significant attention due to their rapid response, high sensitivity, cost-effectiveness and ease of operation. Recently, metal-organic frameworks (MOFs) have been extensively utilized as platforms for constructing fluorescence sensors, owing to their ultra-high porosity, flexible tunability, and excellent luminescent properties. This feature article summarizes the progress made mainly by our research group in recent years in the construction strategies, principles, and types of MOF sensors, as well as their applications in quantitative sensing, qualitative identification analysis, and multimodal/multifunctional analysis. In addition, the challenges and an outlook on the future progression of MOF-based sensors are discussed, highlighting how these studies can contribute to addressing these issues. Hopefully, this feature article can provide some valuable guidance for the construction and application of MOFs in fluorescence sensing, thereby broadening their practical applications. This feature article summarizes the synthesis and application of metal-organic framework-based fluorescence sensors.

Abstract First‐principles computations are performed to investigate the catalytic oxidation of CO on a Ti‐decorated Cr2TiC2O2 MXene monolayer, through comprehensive analysis of charge transfer, electronic density of states, and charge density difference of the interacting systems. By comparing the reaction energy barriers, it is found that, rather than the traditional Langmuir–Hinshelwood, Eley–Rideal, and Mars‐van Krevelen (MvK) mechanisms, the CO oxidation favours a new variant of the MvK mechanism, in which the anchored Ti atom activates the surface oxygen to spill over from the substrate and take part in the CO oxidation. This work highlights the importance of activating the surface oxygen atoms of MXene by foreign metal atoms to improve the catalytic activity, and suggests that further studies into the new MvK mechanism for CO oxidation may prove worthwhile.

Noble metal and semiconductor composite substrates possess high sensitivity, excellent stability, good biocompatibility, and selective enhancement, making them an important research direction in the field of surface-enhanced Raman scattering (SERS). Ta2O5, as a semiconductor material with high thermal stability, corrosion resistance, outstanding optical properties, and catalytic performance, has great potential in SERS research. This study aims to design and fabricate a composite SERS substrate based on Ta2O5 nanostructures, achieving optimal detection performance by combining the urchin-like structure of Ta2O5 with silver nanoparticles (Ag NPs). The urchin-like Ta2O5 nanostructures were prepared using a hydrothermal reaction method. The bandgap was modulated through structure design and the self-doping technique, the charge transfer efficiency and surface plasmon resonance effects were improved, thereby achieving better SERS performance. The composite substrate enables highly sensitive quantitative detection. This composite SERS substrate combines the electromagnetic enhancement mechanism (EM) and chemical enhancement mechanism (CM), achieving ultra-low detection limits of 10-13 M for R6G. Within the concentration range above 10-12 M, there is a good linear relationship between concentration and peak intensity, demonstrating excellent quantitative analysis capabilities. Furthermore, this composite SERS substrate is capable of precise detection of analytes such as crystal violet (CV) and methylene blue (MB), holding broad application prospects in areas such as food safety and environmental monitoring.

Carbon monoxide (CO) oxidation is an efficient way to purify CO. Herein, the geometrical properties, electronic structure and CO oxidation catalytic activity of Zn single atom catalyst (SAC) on pristine Ti2CT2 (T = N/O/F) MXenes and defective ones (Tv/Ti2CT2) with a functional-group vacancy (Tv) were calculated by using density functional theory (DFT) calculations. The results revealed that Ti2CN2 may serve as an excellent substrate to stabilize single Zn atom catalyst, compared to Ti2CT2 (T = O/F) and Tv/Ti2CN2 (T = N/O/F). The catalytic oxidation mechanism of CO on the surface of Zn-Ti2CN2 has been systematically studied. The Eley-Rideal (ER) mechanism was identified as the most preferential pathway with the smallest rate-determining energy barrier of 0.06 eV, since the Zn atom can considerably promote the activation of O2 molecule and weaken the O-O bond. Electronic structure analysis confirmed the synergistic effects of adsorbed single Zn atom and substrate in regulating electron transfer, activating the adsorbed small molecule reactants and enhancing CO oxidation ac-tivity. Overall, this work reveals that Zn-Ti2CN2 could be a promising low-temperature CO oxidation candidate and probably provides a new theoretical guidance and inspiration for the experimental and theoretical research to design more effective single atom catalysts with nonprecious metals.

The geometric stability, electronic structure and catalytic properties towards CO oxidation of a single Pt atom supported on PtS2 , PtSe2 , PtTe2 with a S, Se, and Te vacancies (Pt1/PtX2) were systematically explored by density functional theory calculations. The results showed that the single Pt atom can be located at the vacancy site stably, providing accessible active sites for CO oxidation. Both the Langmuir-Hinshelwood (LH) mechanism and the termolecular Eley-Rideal (TER) mechanism were considered comprehensively. By comparing the rate-determining step ( RDS ) of CO oxidation process, we found that the LH mechanism is easier to achieve. Meanwhile, as the X atom changes from S to Te, the RDS energy barrier gradually decreases, which is attributed to promoted adsorption and activation of O2 molecules on Pt1/PtX2. The results show that Pt1/PtTe2 is the most active catalysts with a low RDS barrier of 0.41 eV. This work provides an important reference for the design of single atom catalysts (SACs) based on transition metal dichalcogenides (TMDs), and has profound implications for the use of supported SACs on defective TMDs for CO oxidation or other reactions.

As the Bragg fiber can guide light by tuning the structure parameters of claddings, it is possible to improve the ability of laser-power transmission in the mid-infrared with effective omnidirectional reflection, but it usually suffers from the disturbance of the air core and functional bandgap. Here, the structural parameters of three pairs of periodic cladding layers were optimized by the plane wave expansion method, and the thickness of each layer is 3.36 µm, consisting of Ge 20 As 20 Se 15 Te 45 and As 2 S 3 glasses with a refractive index contrast of Δn = 0.8. The simulation results showed that a wide bandgap of 1.2 µm can be realized in the fiber after structural optimization. Then, a fiber preform was prepared via an improved stacked extrusion based on seven thickness-compensated glass plates. The experimental results show that the all-solid Bragg fiber has three pairs of uniform periodic cladding and an extra-large core. The superior optical fiber structure can also be well maintained in the whole fiber length, and the average ratio of each cladding thickness to the fiber diameter is kept nearly at 3:100. Finally, the fiber loss at 1.55 µm and 2.94 µm is 12 dB/m and 18 dB/m, respectively. In all, such a well-structured all-solid chalcogenide Bragg fiber would pave a new way to develop high-quality laser transmission or optical sensors in mid-infrared.

The influence of extrusion on the properties of chalcogenide glasses and fibers was investigated systematically via measuring and analyzing their structural and physical properties of Ge10As22Se68 and As2S3. The experimental results showed that the extrusion processing has an insignificant effect on the glass network, crystallization, and compositions, but does have an influence on the glass transmission rate, refractive index and density. Meanwhile, the fiber loss after extrusion processing was greatly improved with 57.65% or 71.43%, corresponding to Ge10As22Se68 or As2S3 fiber, respectively.

We demonstrated a passively Q-switched Er:Ca0.8Sr0.2F2 laser with indium tin oxide nanowire arrays as an optical modulator in the mid-infrared region. In the Q-switched regime, the maximum output power of 58 mW with a slope efficiency of 18.3% was acquired. Meanwhile, the minimum pulse duration and highest repetition rate of the stable pulse trains were 490 ns and 17.09 kHz, corresponding to single pulse energy of 3.4 μJ and peak power of 6.93 W, respectively. To the best of our knowledge it was the first time that indium tin oxide nanowire arrays were employed as a saturable absorber to make pulse lasers carried out at 2.8 μm. The experimental data show that indium tin oxide nanowire arrays can be employed as a competitive candidate for saturable absorber in the field of mid-infrared solid-state lasers.

Two series of novel chalcohalide glasses varying on different molar percentages of cations and anions were prepared successfully. We experimentally investigated the physical optics properties of the chalcohalide hybrid glass (Ge-As-S-Se-I) system. The results show that the short-wavelength cut-off edge (lambda(vis)), linear refractive index (n(0)), and zero-dispersion-wavelength (ZDW) regularly decrease with the increase of anionic iodine mole percentage. And the addition of cationic germanium enhances the glass transition temperature (T-g), softening temperature (T-p) and crystallization temperature (T-x). Besides, a mono-index optical fiber was drawn successfully using the high temperature polymer as the protective layer, with a minimum loss of 1.91 dB/m at 2.6 mu m. Supercontinuum (SC) covering 1.01 similar to 8.32 mu m was generated by pumping the 10-cm-long fiber at a femtosecond laser of 3.78 mu m (similar to 150 fs, 1 kHz, 20 mW). This novel infrared (IR) glass shows great potential in many applications, such as defense military, spectroscopy, long-distance remote sensing.

The efficiency of mode controlling and dispersion tunning in chalcogenide glass fiber is vital to improve the transmission capacity and spectral spanning efficiency in the mid-infrared. A solid-state ring-core fiber (RCF) is designed for mode controlling and dispersion tuning. The simulation results show that LP01-mode is well confined in the high-index cladding-ring, and the confinement loss (CL) analysis of other modes is performed as well. RCF can be regarded as an LP02-mode fiber in the center, which is different from LP01-mode in the step -index fiber when the wavelength is larger than 5.6 mu m. Moreover, OAM0,1 can be stably transmitted in the ring, since LP01-mode and OAM0,1 have identical ring-shaped profiles. For LP02 in the core, the zero-dispersion wavelength (ZDW) can be blue-shifted to 4.4 mu m from 6.7 mu m. For the first time, we have successfully fabricated a novel mid-infrared RCF based on Ge9As22Se69-Ge9As22.5Se68.5-Ge10As22Se68 glasses. The lowest loss is 0.28 dB/m at 8.1 mu m. The supercontinuum (SC) spectra can be effective broadening (1-14.4 mu m) in this RCF via pumping the ZDW around 4.5 mu m. In all, this RCF has great advantages in effective mode controlling and dispersion tuning, and has great potentials in developing broad SC and vortex mode controlling.

Objective The high-birefringence fiber exhibits excellent performance in maintaining light polarization. For the application of high-polarized laser in the mid-infrared field, the exploration of high-birefringence fiber is essential. Increasing the asymmetry of the fiber structure can significantly enhance birefringence; thus, changing the core shape of the traditional fiber structure can increase birefringence up to 10(-4). Therefore, researchers have explored photonic crystal fiber ( PCF) to obtain high birefringence by optimizing the size and arrangement of air holes. Although PCF' s simulated birefringence can reach up to 10(-2) , there is no report about the PCF due to its structural complexity. In this study, we fabricated a novel "-" typed suspended-core chalcogenide fiber with birefringence of approximately 4. 6 x 10(-3) at 5 mu m, which is much higher than that of the traditional quartz polarization-maintaining fiber. We hope that our simulation and experimental data can contribute to further study of high-birefringence fiber in the mid-infrared and pave the way for the further development of mid-infrared high polarization-maintaining fiber optics. Methods In this study, we optimized the fiber structure and calculated its birefringence using the commercial software of COMSOL Multiphysics. First, we selected a kind of "-" typed suspended-core fiber as a basic model for structural optimization due to its largest birefringence among suspended-core fibers. Second, we optimized the fiber structure by changing the core shape, aspect ratio, size, and distance between the two air holes. Finally, we fabricated an improved "-" typed suspended-core chalcogenide fiber based on glass extrusion technology, with Ge10As24Se66 and Ge10As23Se67 acting as core and cladding. We compared the birefringence and analyzed the simulated and experimental data. Subsequently, we calculated the confinement loss and dispersion of the fiber. Results and Discussions The simulation results show that the birefringence of rectangular core fiber is higher than that of elliptical fiber ( Fig. 3). When the aspect ratio of the rectangular core is 3. 6, the birefringence at 1.55 mu m is up to 4.7 X 10(-4), which is higher than that of traditional quartz polarization-maintaining fibers. When the air hole radius is 28 mu m, and the distance between the two air holes is 5. 1 mu m, the birefringence can reach up to 8.1 X 10(-4) and 7. 1 X 10(-3) at 1. 55 and 5 mu m, respectively. The fundamental mode losses in the two orthogonal directions are 3.3 x 10(-12) and 2.6 x 10(-12) dB/m at 1.55 tan. The confinement losses of the two polarization modes reduce to 10(-3) dB/m at 5 tan. However, the birefringence of the fabricated fiber decreases slightly to 4.6 x 10(-3) at 5 mu m due to its deformation during fabrication ( Fig. 8). The deformation might be due to the use of two glasses (having different thermal properties) for the core and cladding. Thus, when the fiber is drawn at a high temperature, the rheological difference between the core and cladding deforms it. Although the simulated and actual birefringence does not fit well, the validity of the overall simulation is proved. Ideal high birefringence can be achieved through experimental optimization in the future. Thus, the simulated and experimental data can provide a base for developing high-birefringence fiber in the mid-infrared. Conclusions The traditional quartz polarization-maintaining fiber cannot be used in the mid-infrared due to its limitation of phonon energy. Contrarily, the simulated birefringence of chalcogenide PCF is much higher. However, there is no experimental report about PCF because of its fabrication complexity. Therefore, this study proposes a novel "-" typed suspended-core chalcogenide fiber with a rectangle core, which is optimized based on the elliptical core fiber model. When the aspect ratio of the rectangular core is 3.6, the air hole radius is 28 mu m, and the distance between the two air holes is 5. 1 mu m, the birefringence can reach up to 7. 1 x 10(-3) at 5 mu m. Additionally, the fundamental mode losses in the two orthogonal directions reduce to 10(-3) dB/m at 5 mu m. We find that the proposed fiber can achieve high birefringence in the mid-infrared. Furthermore, the fiber is fabricated based on chalcogenide glass extrusion technology, and its birefringence can reach up to 4. 6 x 10(-3) at 5 mu m. This study reports all simulation and experimental results for such a suspended-core chalcogenide fiber in the mid-infrared and shows the possibility of a high-birefringence fiber device.

Refractory high-entropy alloy nanocomposites (HEA-NPs) are important class of materials with unique structure and potential applications. Although several synthetic methods have been reported, developing novel routes to prepare nanoscale HEA-based catalysts facilely is still urgently desired. This work takes advantage of confinement assisted arc and plasma shock (APS) to prepare a series of HEA-NPs by regulating the type and proportion of metal precursors. The phase constitutes and morphology of the HEA-NPs are fully characterized. The prepared refractory HEA-NPs possesses five highly dispersed metal components, including titanium (Ti), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo) and simultaneously exhibits an uniform hexagonal morphology of nanocrystals. By taking advantage of its unique corrosion resistance, TiNbTaCrMo HEA-NPs can function as a promising candidate for electrocatalytic hydrogen evolution reaction (HER) in natural seawater. And its catalytic performance after alloying is significantly enhanced compared with the elemental metal. Theoretically, the promoted HER activity can be attributed to the strong adsorption for the various metal components in HEA-NPs caused by the upshifting d-band center close to the Fermi level. Furthermore, this confinement strategy can be further extended to synthesize other HEA-NPs. Our strategy provides a novel method to synthesize various HEA-NPs for further catalytic application.