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With the rapid development of miniaturization, high power and high integration of electronic components, multifunctional materials have attracted tremendous attention. Herein, the multifunctional aramid nanofibers@polypyrrole (ANF@PPy) composite films are prepared through a facile vacuum filtration method after the an in-situ polymerization of PPy on the surface of ANF, which are applied in broadband frequency electromagnetic interference (EMI) shielding, wearable sensor, Joule heating, photothermal conversion. ANF@PPy-4 composite film with thin thickness of 46 µm displays excellent EMI shielding effectiveness (EMI SE) of 35 dB for C-band, X-band, Ku-band and K-band of electromagnetic wave. Furthermore, the relative resistance variation of ANF@PPy-4 composite film can be recorded for monitoring human motions, such as finger, wrist, elbow, knee, ankle, forearm and throat (vocal cord vibration). In addition, the saturation temperature of ANF@PPy-4 composite film is about 77 ºC at a low working voltage of 5.0 V. Moreover, temperature of ANF@PPy-4 composite film can reach to 54 ºC via the photothermal conversion under one sun irradiation. Multifunctional ANF@PPy composite films show enormous potential application of broadband frequency EMI shielding, wearable sensor, personal thermal management.

Multiferroic materials with the cross-coupling of magnetic and ferroelectric orders provide a new platform for physics study and designing novel electronic devices. However, the weak coupling strength of ferroelectricity and magnetism is the main obstacle for potential applications. The recent research focuses on enhancing the coupling effect via synthesizing novel materials in a chemical route or tuning the multiferroicity in the physical way. Among them, pressure is an effective method to modify multiferroic materials, especially when the chemical doping has reached its tuning limit. In this work, we systemically studied the multiferroic properties in a hydrogen-bonded metal-organic framework (MOF) [(CH

GeP5, as the most representative phosphorus-based material in two-dimensional layered phosphorous compounds, has shown a fairly bright application prospect in the field of energy storage because of its ultrahigh electrical conductivity. However, high-yield exfoliation methods and effective structure construction strategies for GeP5 nanosheets are still missing, which completely restricts the further application of GeP5-based nanocomposites. Here, we not only improved the yield of GeP5 nanosheets by a liquid nitrogen-assisted liquid-phase exfoliation technique but also constructed the GeP5@RuO2 nanocomposites with the 0D/2D heterostructure by in situ introduction of ultrafine RuO2 nanoparticles on highly conductive GeP5 nanosheets using a simple hydrothermal synthesis method, and then applying it to micro-supercapacitors (MSCs) as electrode materials through a mask-assisted vacuum filtration technique. It is precisely because of the synergy of the electrical double-layer material, GeP5 nanosheets and the pseudocapacitance material RuO2 nanoparticles that endows the GeP5@RuO2 electrode with outstanding electrochemical performance in micro-supercapacitors with a large specific capacitance of 129.5 mF cm-2/107.9 F cm-3, high energy density of 17.98 μWh cm-2, remarkable long-term cycling stability with 98.4% capacitance retention after 10 000 cycles, the exceptional mechanical stability, outstanding environmental stability, and excellent integration features. This work opens up a new avenue to construct GeP5-based nanocomposites as a most promising novel electrode material for practical application in flexible portable/wearable micro-nanoelectronic devices.

Two-dimensional van der Waals (vdW) ferromagnetic materials have attached a significant attention for developing miniaturized electronic devices. Fe3GeTe2 (FGT) as two-dimensional vdW materials with intrinsic ferromagnetism has high Curie temperature, which have potential applications in overcoming microwave pollution and radiation. Herein, a single-crystal FGT is synthesized using a self-flux method and then dissociated into nanosheets via the liquid-phase exfoliation technique. Curie temperature of FGT nanosheets powder is approximately 230 K, which is close to room temperature. FGT nanosheets as microwave absorber exhibit low reflection loss (RL) due to poor impedance matching. The microwave absorption properties of FGT nanosheets are improved by introducing graphene nanosheets (GNS). FGT@GNS 1–2 composites exhibit excellent microwave absorption performance. The minimum RL of FGT@GNS 1–2 reach − 44.43 dB at a microwave frequency of 9.9 GHz, when thickness is only 1.45 mm. This meets the requirements of strong RL and thin thickness of microwave absorption materials, indicating that FGT@GNS composites have a potential application for overcoming microwave pollution and radiation.

Low dimensional semiconductors can be used for various electronic and optoelectronic devices because of their unique structure and property. In this work, one-dimensional Sb2S3 nanowires (NWs) with high crystallinity were grown via chemical vapor deposition (CVD) technique on SiO2/Si substrates. The Sb2S3 NWs exhibited needle-like structures with inclined cross-sections. The lengths of Sb2S3 nanowires changed from 7 to 13 μm. The photodetection properties of Sb2S3 nanowires were comprehensively and systematically characterized. The Sb2S3 photodetectors show a broadband photoresponse ranging from ultraviolet (360 nm) to near-infrared (785 nm). An excellent specific detectivity of 2.1 × 1014 Jones, high external quantum efficiency of 1.5 × 104 %, sensitivity of 2.2 × 104 cm2W−1 and short response time of less than 100 ms was achieved for the Sb2S3 NW photodetectors. Moreover, the Sb2S3 NWs showed outstanding switch cycling stability that was beneficial to the practical applications. The high-quality Sb2S3 nanowires fabricated by CVD have great application potential in semiconductor and optoelectronic fields.

Pressure, as an independent thermodynamic parameter, is an effective tool to obtain novel material system and exotic physical phenomena not accessible at ambient conditions, because it profoundly modifies the charge, orbital and spin state by reducing the interatomic distance in crystal structure. However, the studies of magnetoelectricity and multiferroicity are rarely extended to high pressure dimension due to properties measured inside the high pressure vessel being a challenge. Here we reported the temperature-magnetic field-pressure magnetoelectric (ME) phase diagram of Y type hexaferrite Ba

The structures of the various phases endow In2Se3 unique properties as well as a broad range of potential applications. However, the controversy on the structures of In2Se3 strongly hinders the exp...

GeP

Structural defects play an important role in exploitation of two-dimensional layered materials (2DLMs) for advanced biosensors with the increasingly high sensitivity and low detection limit. Grain boundaries (GBs), as an important type of structural defect in polycrystalline 2DLM films, potentially provide sufficient active defect sites for the immobilization of bioreceptor units via chemical functionalization. In this work, we report the selective functionalization of high-density GBs with complementary DNA receptors, via gold nanoparticle (AuNP) linkers, in wafer-scale polycrystalline monolayer (1L) W(Mo)S

Permeable concrete is required to have adequate strength, water permeability, and freeze-thaw resistance as pavement material. The purpose of this research is to improve the properties of f...

With the rapid development of wearable electronic and smart electronic devices, the flexible supercapacitors have attracted special attention in energy storage and conversion. Indium selenide (InSe) as a novel two-dimensional layered material has been widely investigated in photodetector, solar cell, and so on due to high electron mobility, anomalous optical response and tuning the bandgap. InSe nanoflakes are obtained from bulk layered InSe materials via a liquid-exfoliation technique and used as electrodes materials of supercapacitors. Flexible all-solid-state supercapacitors (ASSPs) with sandwich structure using InSe nanoflakes have a volumetric capacitance of 3.48 F cm−3 at a scan rate of 0.005 V s−1. For improving the performance of ASSPs based on InSe, highly conductive carbon nanotubes (CNTs) are added into InSe nanoflakes to enhance the conductivity of InSe/CNTs composites used as electrodes of ASSPs. InSe/CNTs (mass ratio 6:1) ASSPs deliver high volumetric capacitance of 25.1 F cm−3 at a scan rate of 0.005 V s−1, good mechanical properties (93.2% capacitance at 180° bending) and long cycle stability (88.3% capacitance after 10000 cycles). In addition, ASSPs based on InSe/CNTs composites exhibit a high power density of 410.15 W cm−3 and a superior energy density of 3.48 mWh cm−3. The InSe/CNTs composite is expected to have a potential candidate in high-performance electrochemical energy storage devices.

Carbonaceous photonic crystals (CPCs) were prepared from peacock feather fibers (PFF) via high-temperature carbonization (HTC) and hydrothermal carbonization (HC), and by comparing the optical reflection microphotographs, the CPCs-HTC and CPCs-HC still owned the structural coloration as the natural PFF. Raman results showed that the ID/IG value of CPCs-HTC was higher than the one of CPCs-HC, demonstrating more defects and higher graphitization degree of CPCs-HTC. Due to the presence of defects and the different degrees of graphitization, complex permittivity of CPCs can be controlled. The microwave absorption performance of 30 wt% CPCs-HTC was better than the CPCs-HC. The minimum reflection loss (RL) of CPCs-HTC was − 57.9 dB when the frequency was 7.3 GHz and the thickness was 2.5 mm. The frequency range, in which the RL values were less than − 10 dB, was 6.4–8.5 GHz. Compared with other biomass-derived materials, the CPCs-HTC shows several advantages, such as the specific photonic structure, simple preparation process and excellent microwave absorption performances. Thus, CPCs-HTC has the potential to be a lightweight microwave absorption material.

Composites that consist of ceramic and C materials have attracted considerable attention in the microwave absorption field. In this work, we applied a facile and scalable synthesis strategy to prepare B4C nanoparticles with core–shell structures. XRD and Raman results confirmed the existence of B4C and amorphous C in the core–shell B4C nanoparticles. Morphological analysis revealed that the B4C nanoparticles exhibited regular morphologies with average diameter of approximately 100 nm and were well encapsulated by amorphous C shells. The C-coated B4C nanoparticles fabricated with a B/C ratio of 1:1.25 and with thicknesses of 1.5 mm provided the lowest reflection loss value of −60.8 dB at 15.5 GHz. The C coated B4C nanoparticles have considerable potential uses as microwave absorbers given their facile preparation and excellent microwave absorption performance.

Alloying is an effective way to modulate material’s properties. In particular, graded alloying within a single domain of two-dimensional transition-metal chalcogenide (2D-TMC) is of great technolog...

Due to its potential application in magnetic memory, the vortex magnetization configuration has drawn much attention, which had been found in many magnetic nanostructure. In this paper, static and dynamic characteristics of magnetism in permalloy oval nanoring are investigated with varying thickness and arm width via micromagnetic simulation. Two magnetization configuration (vortex and onion states) were found in oval nanoring and the vortex state is a stable state. Although onion is a metastable state, it become more stable with the decrease of thickness. The magnetic hysteresis loop along long axis of oval nanoring is simulated and coercive forces are investigated as function of arm width and thickness. Coercive force increases firstly and then decrease with the increase of thickness. In meanwhile, the dynamic magnetic susceptibility of vortex state in oval nanoring is simulated for varying arm width and thickness. Uniform resonance mode and edge resonance mode can be found when thickness is above 25 nm. However, there is a single uniform resonance mode in oval nanoring with thickness less 20 nm. The resonance frequency can be significantly modulated in the region of 8.2–13.7 GHz when thickness changes from 4 to 100 nm.

Two-dimensional (2D) layered magnetic materials have attracted great attention in recent years because of the discovery of long-range order of magnetism down to the monolayer and its expected appli...

The NiCo2 nanoparticles and NiCo2/carbon nanotubes (CNTs) nanohybrids were prepared by a single-model microwave heating and annealing treatment. It was found that the NiCo2 nanoparticles were evenly distributed around with CNTs. As a result, the complex permittivity of NiCo2/CNTs nanohybrids could be adjusted effectively, and achieved a well impedance matching for the microwave absorption. The dielectric loss, magnetic loss mechanism and the impedance matching were also investigated systematically. As a result, the reflection loss (RL) less than −20 dB (99% absorption) were observed at 3.7–16.5 GHz with the thickness of 1.2–4.0 mm; moreover, the maximum bandwidth of the RL values less than −10 dB (90% absorption) was 4.4 GHz (12.5–16.9 GHz), and a minimum RL value of −25.5 dB could be observed at 14.7 GHz with the thickness of 1.3 mm. These performances revealed that the NiCo2/10%CNTs nanohybrids have a great potential to be used as the lightweight microwave absorption material.

Next-generation high-performance biological and chemical sensors based on the emerging multitudinous two-dimensional (2D) layered materials have been attracting great attention in recent years. The performance of 2D biochemical sensors is strongly dependent on the structural defects, which provide indispensable active sites for sensitive and selective adsorption of analytes. However, achieving controllable defect engineering is still a big challenge. In the present work, we propose achieving superior biochemical sensor performance with high-surface-density grain boundaries (GBs), a kind of ubiquitous structural defects, in polycrystalline 2D thin films, which can be controllably synthesized. As a proof-of-concept, by utilizing the high-density GBs in monolayer (1L) WS2 films, we fabricated a series of surface plasmon resonance (SPR) sensors for mercury ion (Hg2+) detection. Our investigation has demonstrated substantial sensitivity enhancement of Hg2+ detection down to trace attomolar-level quantification (detection limit of 1 aM), which is ascribed to the abundance of active sites on high-density GBs. This work provides a promising avenue for the design of ultra-sensitive sensors toward commercialized products based on the GB-rich 2D layered materials.

Preferentially exposed active edges are advantageous in the application of two-dimensional materials (2DMs) in high-performance biochemical sensors. Despite current progresses, controllable large-scale production of edge-rich 2DM films for practical applications remains a challenge. In this work, we report the controllable single-step growth of wafer-scale edge-rich WS2 films of high-density nanoscale multilayer WS2 islands and their application in sensitive, low detection limit biochemical sensors. The abundant edge active sites are shown to be crucial to their superior biochemical sensing performance. Investigations reveal that high-density edge S-active sites enable the highly sensitive attomolar-level Hg2+ detection as direct target probes via selective Hg-S bonding. Furthermore, 1 fM level selective detection of target viral nucleic acids (RdRp, ORF1ad) are achieved via functionalization of active edge sites with cDNA receptors. Our investigations provide a comprehensive method for application of similar edge-rich 2DM films in high-performance sensors for broad ranges of analytes. Data and materials availability The authors declare that the data supporting the findings of this study are available within the paper and its Supplementary Materials .

Perovskite-like ABX3 metal-organic frameworks (MOFs) have gathered great interest due to their intriguing chemical and physical properties, including their magnetism, ferroelectricity, and multiferroicity. Pressure is an effective thermal parameter in tuning related properties in MOFs due to the adjustable organic framework. Though spectrum experiments have been made on the structural evolution during decompression, there is a lack of electrical studies on the order-disorder ferroelectric transition in the metal-organic frameworks under pressure. In this work, we use a static pyroelectric current measurement, a dynamic dielectric method combined with a Raman scattering technique with applying in situ pressure, to explore the order-disorder ferroelectric transition in [(CH3)2NH2]Co(HCOO)3. The ferroelectric transition vanishes around the external pressure of 1.6 GPa, emerging with a new paraelectric phase. Another phase transition was observed at 6.32 GPa, mainly associated with the distortive transition of DMA+ cations. A phenomenological theory of ferroelectricity vanishing at 1.6 GPa for [(CH3)2NH2]Co(HCOO)3 is also discussed. Our study gives a comprehensive understanding in the pressure tuning of ferroelectric properties in hybrid inorganic-organic materials.

The Ni@C nanohybrids were prepared by a unique and efficient method of annealing the organic carbon compound and metal nitrate. Morphology detection demonstrated the Ni nanoparticles were uniformly encapsulated into the carbon network. The microwave absorption of 10 wt % Ni@C nanohybrids with paraffin matrix was measured over the range of 1–18 GHz. The complex permittivity was adjusted by changing the carbon proportions because of the superior conductivity of graphite. The minimum reflection loss (RL) value of −56 dB was obtained at 15.8 GHz with a thickness of 1.8 mm and the effective absorption bandwidth (RL ≤ −10 dB) was 5.4 GHz. Therefore, the Ni@C nanohybrids have great potential to be utilized as a high-efficiency and lightweight microwave absorber.

It involves invariably strong expectations and a tough challenge to explore lightweight microwave absorption materials with high efficiency and agile tenability. Here, we successfully synthesized CoFe

In this work, carbonaceous photonic crystals (CPCs) were obtained by the carbonization of butterfly wings, and the CPCs/magnetic particle (Fe3O4 and Fe) nanohybrids with heterostructure were synthesized by a facile single-mode microwave-assisted hydrothermal method. Scanning electron microscopy and transmission electron microscopy images indicated that CPCs exhibited a distinct structure of a periodic network interconnected by ridges and ribs with a highly smooth surface. The magnetic nanoparticles were also uniformly attached on the ridges and ribs of CPCs. The microwave absorption performances of CPCs/Fe3O4 and CPCs/Fe nanohybrids with heterostructure were investigated. The minimum reflection loss (RL) were −49.7 and −31.2 dB for CPCs/Fe3O4 and CPCs/Fe nanohybrids, respectively. The effective bandwidths (RL

Nitrogen dioxide (NO2) as one of the most serious air pollution is harmful to people’s health, therefore high-performance gas sensors is critically needed. Here, Cu-modified carbon spheres/reduced graphene oxide (Cu@CS/RGO) composite have been prepared as NO2 gas sensor material. Carbon sphere in the interlayer of RGO can increase the specific surface area of RGO. Copper nanoparticles decorated on the surface of CS can effectively enhance the adsorption activity of RGO as supplier of free electrons. The experimental results showed that its particular structure improved the gas sensitivity of RGO at different NO2 concentrations at room temperature.

In this study, high quality GeP5 crystals with two-dimensional (2D) layered structures and novel electrical conductivity of 2.4 × 106 S m−1 have been prepared under high-temperature high-pressure oriented growth technique (HTHP-OGT). The as-synthesized GeP5 nanoflakes, after liquid phase exfoliation, show promising potential for application as electrode materials in all-solid-state supercapacitors (ASSPs). The as-prepared GeP5-ASSP exhibits excellent electrochemical performances, including an ultrahigh scan rate of 1000 V s−1, a high specific capacitance of up to 35.86 F cm−3 at 5 mV s−1, a great power density of 397.24 W cm−3 and an energy density of 4.98 mW h cm−3. Moreover, the device can retain 83.7% and 88% of the initial capacitance retention at 180° bending and after 10 000 cycles, respectively, showing outstanding flexibility and superior cycling stability. These properties indicate the promising application of the metallic layered GeP5 for flexible energy storage devices.

Thin films of millimeter-scale continuous monolayer WS2 have been grown on SiO2/Si substrate, followed by the deposition of β-In2Se3 crystals on monolayer WS2 to prepare In2Se3/WS2 van de Waals heterostructures by a two-step chemical vapor deposition (CVD) method. After the growth of In2Se3 at elevated temperatures, high densities of In2Se3/WS2 heterostructure bubbles with monolayer to multilayer β-In2Se3 crystals atop are observed. Fluorescence of the resultant β-In2Se3/WS2 heterostructure is greatly enhanced in intensity upon the formation of bubbles, which are evidenced by the Newton’s rings in optical image owing to constructive and destructive interference. In photoluminescence (PL) mapping images of monolayer β-In2Se3/monolayer WS2 heterobilayer bubble, significant oscillatory behavior of emission intensity is demonstrated due to constructive and destructive interference. However, oscillatory behaviors of peak position are also observed and come from a local heating effect induced by an excitation laser beam. The oscillatory mechanism of PL is further verified by changing the exterior pressure of bubbles placed in a home-made vacuum chamber. In addition, redshifted in peak position and broadening in peak width are observed due to strain effect during decreasing the exterior pressure of bubbles.

Conductive materials have been widely studied as the dielectric loss type microwave absorption absorbers due to their specific properties. In this work, Molybdenum disulfide @polypyrrole (MoS2@Ppy) composites were prepared through microwave-assisted hydrothermal method followed by in-situ polymerization. The MoS2 nanoparticles showed three-dimensional flower-like structures. The Ppy nanoparticles were uniformly coated on the surface of MoS2, and some of small Ppy particles were embed in the folds of flower-like MoS2. The complex permittivity of composites was greatly enhanced because of the high conductivity of Ppy. The microwave absorption performances of MoS2@Ppy composites were investigated systematically. For the MoS2@100py composite, the minimum RL of −61.1 dB was obtained at 11.2 GHz under the thickness of 2.28 mm. Compared with the related materials, the MoS2@Ppy composite showed strong microwave energy attenuation, thin thickness and broad absorption bandwidth. The MoS2@Ppy composites have great potential application values as the high-efficiency microwave absorber.

Structural defects play an important role in exploitation of two-dimensional layered materials (2DLMs) for advanced biosensors with the increasingly high sensitivity and low detection limit. Grain boundaries (GBs), as an important type of structural defect in polycrystalline 2DLM films, potentially provide sufficient active defect sites for the immobilization of bioreceptor units via chemical functionalization. In this work, we report the selective functionalization of high-density GBs with complementary DNA receptors, via gold nanoparticle (AuNP) linkers, in wafer-scale polycrystalline monolayer (1L) W(Mo)S2 films as versatile plasmonic biosensing platforms. The large surface area and GB-rich nature of the polycrystalline 1L WS2 film enabled the immobilization of bioreceptors in high surface density with spatial uniformity, while the AuNPs perform not only as bioreceptor linkers, but also promote detection sensitivity through surface plasmon resonance enhancement effect. Therefore, the presented biosensor demonstrated highly sensitive and selective sub-femto-molar detection of representative RNA sequences from the novel coronavirus (RdRp, ORF1ad and E). This work demonstrates the immense potential of AuNP-decorated GB-rich 2DLMs in the design of ultra-sensitive biosensing platforms for the detection of biological targets beyond RNA, bringing new opportunities for novel healthcare technologies.

The layered transition metal dichalcogenides (TMDs) exhibit the intriguing physical properties and potential application in novel electronic devices. However, controllable growth of multilayer TMDs remains challenging. Herein, large-scale and high-quality multilayer prototype TMDs of W(Mo)Se2 were synthesized via chemical vapor deposition. For Raman and photoluminescence measurements, 2H and 3R multilayer WSe2 crystals displayed significant layer-dependent peak position and intensity feature. Besides, different from the oscillatory relationship of second harmonic generation (SHG) intensity for odd–even layer numbers in 2H-stacked multilayer WSe2, the SHG intensity of 3R-stacked ones parabolically increased with the thickness due to the absence of inversion symmetry. For device application, photodetectors based on WSe2 with increasing thickness exhibited p-type (bilayer), ambipolar (trilayer), and n-type (four layers) semiconductor behaviors, respectively. Furthermore, photodetectors based on the as-synthesized 3R-stacked WSe2 flakes displayed an excellent responsivity of 7.8 × 103 mA W−1, high specific detectivity (Da*) of 1.7 × 1014 Jones, outstanding external quantum efficiency of 8.6 × 102%, and fast response time (τ Rise = 57 ms and τ Fall = 53 ms) under 532 nm illumination with bias voltage of V ds = 5 V. Similar results have also been achieved in multilayer MoSe2 crystals. All these findings indicate great potential of 3R-stacked TMDs in two-dimensional optoelectronic applications.

Microwave absorption materials with high reflection loss (RL), thin thickness and wide absorption bandwidth have attached a lot of attention for overcoming microwave pollution. Nanocomposites composed of carbon-based materials and metal sulfide have excellent microwave absorption properties, which meet the high RL of low weight microwave absorbing materials. In this study, binary nanocomposites of spherical-like nickel sulfide (NiS2) decorated on reduced graphene oxide (rGO) were successfully prepared using a one-step single-mode microwave-assisted hydrothermal method. Morphological analysis using scanning electron microscopy and transmission electron microscopy indicated that the NiS2 particles were evenly wrapped by rGO. The rGO/NiS2 nanocomposites were used as microwave absorption materials and their electromagnetic parameters were measured in the range of 1.0–18.0 GHz. For the rGO/NiS2 1:5 nanocomposite with a very thin thickness of 1.59 mm, the minimum RL and effective absorption bandwidth reached −33.72 dB and 4.37 GHz, respectively. The microwave absorption performance of the nanocomposites improved by adjusting the impedance upon changing the mass fraction of NiS2. Therefore, rGO/NiS2 nanocomposites with high RL and thin thickness have great application prospects for microwave absorption.

In this paper, we report CoP nanowires supported on carbon cloth (CC) (CoP/CC) as a bifunctional electrode for hydrogen evolution reaction (HER) and supercapacitor. CoP/CC possess an excellent electrocatalytic performance for HER, with a Tafel slope of 56 mV/dec and a low overpotential of 68 mV to achieve a current density of 10 mA cm−2 . Remarkably, the bifunctional CoP/CC used as electrode for supercapacitor exhibit a higher specific capacitance of 674 F g−1 at a scan rate of 5 mV s−1 and maintains long-life cycling stability, retaining 86% of the initial capacitance after 10,000 cycles. CoP/CC will be a promising candidate as electrode for HER and supercapacitor.

Tensile strain is intrinsic to monolayer crystals of transition metal disulfides such as Mo(W)S2 grown on oxidized silicon substrates by chemical vapor deposition (CVD) owing to the much larger thermal expansion coefficient of Mo(W)S2 than that of silica. Here we report fascinating fluorescent variation in intensity with aging time in CVD-grown triangular monolayer WS2 crystals on SiO2 (300 nm)/Si substrates and formation of interesting concentric triangular fluorescence patterns in monolayer crystals of large size. The novel fluorescence aging behavior is recognized to be induced by the partial release of intrinsic tensile strain after CVD growth and the induced localized variations or gradients of strain in the monolayer crystals. The results demonstrate that strain has a dramatic impact on the fluorescence and photoluminescence of monolayer WS2 crystals and thus could potentially be utilized to tune electronic and optoelectronic properties of monolayer transition metal disulfides.