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A shape-variable aqueous secondary battery operating at low temperature is developed using Ga68In22Sn10 in wt% liquid metal anode and conductive polymer (polyaniline (PANI)) cathode. While in the GaInSn alloy anode, Ga is the active constituent; Sn and In increase the acid resistance and decrease the eutectic point to -19°C. This enables the use of strongly acidic aqueous electrolytes (here, pH 0.9), thereby improving the activity and stability of the PANI cathode. Consequently, the battery exhibits remarkable excellent electrochemical performance and mechanical stability. The GaInSn–PANI battery operates via a hybrid mechanism of Ga3+ stripping/plating and Cl− insertion/extraction and delivers a high initial capacity of over 324.6 mAh g− 1 and a 52.4% retention rate at 0.2 A g− 1 after 500 cycles, and outstanding power and energy densities of 4300 mW g− 1 and 98.7 mWh g− 1, respectively. Because of the liquid anode, the battery without packaging can be deformed with a small force of several millinewtons without any capacity loss. Moreover, at approximately − 5°C, the battery delivers a capacity of 67.8 mAh g− 1 at 0.2 A g− 1 with 100% elasticity. Thus, the battery is promising as a deformable energy device at low temperatures and in demanding environments.

In this study, we report the construction of a novel composite photocatalyst (BiVO

Highly strain-endurable gas sensors were implemented on fabric, which was taken from a real T-shirt, employing a sequential coating method. Multidimensional, functional nanostructures such as reduced graphene oxide, ZnO nanorods, palladium nanoparticles, and silver nanowires were integrated for their realization. It was revealed that the fabric gas sensors could detect both oxidizing and reducing gases at room temperature with differing signs and magnitudes of responses. Noticeably, the fabric gas sensors could normally work even under large strains up to 100%, which represents the highest strain tolerance in the gas sensor field. Furthermore, the fabric gas sensors turned out to bear harsh bending and twisting stresses. It was also demonstrated that the sequential coating method is an effective and facile way to control the size of the fabric gas sensor.

In order to further improve its photocatalytic activity, the BiOI microspheres were activated by a synchronous coupling of Bi metal and graphene under solvothermal conditions. The effects of the synthesis temperature (160–200 °C) on crystallinity, morphology, and photocatalytic activity were studied in particular. As expected, the ternary Bi-BiOI/graphene photocatalyst synthesized at 180 °C exhibited higher photocatalytic activity for NO oxidation removal under visible light irradiation than individual BiOI, and binary Bi-BiOI and BiOI/graphene composites. The photocatalytic efficiency for the NO removal of the ternary Bi-BiOI/graphene photocatalyst synthesized at 180 °C reached 51.8% within 30 min of visible light irradiation. The enhanced photocatalytic activity of the ternary Bi-BiOI/graphene photocatalyst is attributed to (I) the efficient transfer of photo-generated electrons from BiOI and Bi to graphene, leading to the effective separation of the photo-generated electron-hole pairs and (II) the surface plasmon resonance effect of Bi nanoparticles in the composite photocatalyst. Furthermore, the results of the scavenger experiments and DMPO-ESR spin-trapping measurements reveal that O2− radical species play the most critical role and holes serve as a secondary active species in the oxidative removal process of NO by 180BOI/GR composite under visible light irradiation.

We report significant enhancement of photocatalytic properties of g-C3N4 by a facile Lithium (Li)-intercalation method. The Li atoms are successfully and stably intercalated into the interlayer of g-C3N4 by n-butyl lithium (n-BuLi). The photocatalytic activity of the Li-intercalated g-C3N4 was observed to be significantly improved by 2.8 times in degradation of a dye (RhB), compared to that of pristine g-C3N4. The synergetic effects of the narrowed band gap, enhanced surface area, establishment of an interlayer pathway, and positive shift in the valence band position improve the photocatalytic activity of the Li-intercalated g-C3N4. Our discovery provides a promising route to manipulate the photocatalytic activity simply by increasing the Li concentration after the growth process of the g-C3N4, gaining a deeper understanding of the improvement in the photocatalytic efficiency.

In this paper, a topography-controlled ZnO nano-petal array has been fabricated on liquid metal (Ga75.5In24.5) surface, and possesses not only superhydrophobicity and anti-fogging in low temperature but also robust heat transfer efficiency. The rough nano-petals prevent water layer formation at initial time, and maintain robust performance in enhancing the coalescence of condensed droplets, leading to excellent self-cleaning properties. In addition, the liquid metal used as cushioning materials with robust heat transfer character, has been identified as one of the most appropriate materials to enhance heat transmission.

Molybdenum diselenide (MoSe2) nanosheets thin film gas sensor was firstly fabricated and its sensing potential to ppm-level ethanol vapor at low operating temperature was investigated. Ultrathin MoSe2 nanosheets were prepared in large scale through a facile liquid-phase exfoliation method using low-boiling-temperature solvent. The exfoliated MoSe2 nanosheets exhibited high purity and crystallinity with few atomic layer thickness. Systematical gas sensing tests demonstrated that MoSe2 nanosheets based thin film could be utilized as ethanol gas sensor with linear response, quick recovery, and good repeatability at 90 °C. The sensing mechanism of MoSe2 toward ethanol was investigated based on first principle calculation. The adsorption behavior of ethanol molecules on MoSe2 surface was revealed in light of adsorption orientation, adsorption energy, charge transfer, projected electronic density of state, and molecular orbital. The calculation well matched with experimental results. It is found the quick and completed recovery of MoSe2 nanosheets sensor was benefited by the appropriate physical interaction between ethanol and MoSe2 surface. This finding offers a competitive option instead of conventional graphene sensor for ethanol gas detection at low temperature.

In order to overcome the disadvantages of uncontrollable particle size, slow speed and high energy consumption existing in traditional phosphor preparation methods, we successfully prepared YAG:Ce and YAG:Dy phosphors rapidly and conveniently by using a laser sintering method with low energy consumption. The influence of different laser powers (3–27 W), scanning rates (50–800 mm s−1), powder thicknesses (50–800 μm), doping concentrations (0.25–1%), and post-treatments on their phase purity, morphology and optics was investigated. Spherical YAG phosphors with controllable particle size could be obtained through selecting appropriate parameters, and their PL intensity was enhanced by 300% after annealing; the average particle size was decreased to 46 μm after reducing the powder thickness to 50 μm. These results suggest that the reaction temperature and preparation period are greatly reduced compared with the conventional solid-state reaction method. A luminous efficiency (LE) of 80 lm W−1 and color rendering index (CRI) of 76.4 can be reached for the fabricated WLED using YAG:Ce phosphor, demonstrating its great potential applications in WLEDs. Interestingly, it is found that YAG:Dy phosphors exhibit red, pink, orange-yellow and pale-yellow emission color under various excitation wavelengths, showing significant potential application in the fields of anti-counterfeiting and fluorescent labeling. In short, according to our research, the laser sintering method has been proved to have a great potential application in the field of phosphor preparation.

A series of novel red emitting Mn2+-activated SrZnSO phosphors were successfully synthesized by solid-state reaction at high temperature. The photoluminescence (PL) and mechanoluminescence (ML) properties of these Mn2+-activated SrZnSO phosphors with different Mn2+ concentrations were investigated. With increasing the concentration of Mn2+ from x = 0 to 0.04, the unit cell volume increased from 153.82 to 154.19 A3 while the optical band gap decreased from 3.74 to 3.43 eV. The site occupation of Mn2+ in the host lattice was demonstrated by Rietveld refinement, the electron paramagnetic resonance (EPR) spectrum, and the spectroscopic properties. A broad band emission peak at 603 nm of SrZn1−xMnxSO (0.001 ≤ x ≤ 0.04) with an excitation wavelength of 318 nm was attributed to electronic transitions of Mn2+ from the 4T1(4G) level to the 6A1(6S) level. The lifetime of SrZn1−xMnxSO (0.001 ≤ x ≤ 0.04) decreased monotonously from 2.97 to 0.82 ms with increasing Mn2+ concentration. In particular, intense emission of red light from SrZn1−xMnxSO (0.001 ≤ x ≤ 0.04) under compressive load could be observed even with the naked eye, indicating that SrZn1−xMnxSO could be used for stress sensors or stress imaging. There was a linear correlation between the ML intensity and external load in SrZn1−xMnxSO, and the ML intensity could be recovered under UV light irradiation. Considering its advantages of non-destruction, reproducibility, and high ML intensity, SrZn1−xMnxSO might be useful for non-destructive detection of stress.

The Z-scheme BiVO

Two-dimensional (2D) van der Waals (vdW) heterostructures exhibit novel physical and chemical properties, allowing the development of unprecedented electronic, optical, and electrochemical devices. However, the construction of wafer-scale vdW heterostructures for practical applications is still limited due to the lack of well-established growth and transfer techniques. Herein, we report a method for the fabrication of wafer-scale 2D vdW heterostructures with an ultraclean interface between layers via the aid of a freestanding viscoelastic polymer support layer (VEPSL). The low glass transition temperature ( Tg) and viscoelastic nature of the VEPSL ensure absolute conformal contact between 2D layers, enabling the easy pick-up of layers and attaching to other 2D layers. This eventually leads to the construction of random sequence 2D vdW heterostructures such as molybdenum disulfide/tungsten disulfide/molybdenum diselenide/tungsten diselenide/hexagonal boron nitride. Furthermore, the VEPSL allows the conformal transfer of 2D vdW heterostructures onto arbitrary substrates, irrespective of surface roughness. To demonstrate the significance of the ultraclean interface, the fabricated molybdenum disulfide/graphene heterostructure employed as an electrocatalyst yielded excellent results of 73.1 mV·dec-1 for the Tafel slope and 0.12 kΩ of charge transfer resistance, which are almost twice as low as that of the impurity-trapped heterostructure.

A crystal-damage-free nanodoping method, which utilized the vacuum drive-in diffusion of Al into ZnO nanorods, was developed. In this method, vertical ZnO nanorod arrays that were grown by chemical bath deposition beforehand were deposited with Al thin film and subsequently heat-treated under a high vacuum. At an optimum condition, the surface Al atoms were completely diffused into ZnO nanorods, resulting in Al-doped ZnO nanorods. Stretchable gas sensors were fabricated by sequentially drop-casting the Al-doped ZnO nanorods and silver nanowires on polydimethylsiloxane substrate. The resistance and response of the sensor could be optimized through the elaborate control of relative densities of Al-doped ZnO nanorods and silver nanowires. The sensor showed a high response of 32.3% to 10 ppm of NO2 gas at room temperature, even under a large strain of 30%. The NO2-sensing mechanism of Al-doped ZnO nanorod/silver nanowire bilayer sensors is discussed on the basis of a synergistic interplay of Al-doped ZnO nanorods and silver nanowires.

We investigated the optical behaviour of excitons in monolayer MoS 2 prepared on a 60 nm-thick metal (Au) ring structure patterned on SiO 2 . CVD-grown monolayer MoS 2 was transferred to the metal structure and placed in contact with three different environments simultaneously: SiO 2 , Au metal and air. The optical properties of the transferred MoS 2 on the substrates were characterized through micro-photoluminescence (μ-PL) measurements. PL peaks were observed near ∼1.82 eV for defect-related emission, ∼1.92 eV for an A exciton, which includes a neutral exciton and a trion, and ∼2.1 eV for a B exciton. The optical band gap and exciton-phonon interaction of the samples on the three substrates were investigated by measuring the temperature-dependent photoluminescence.

Uniform, monodisperse yttrium aluminum garnet (YAG) rhombic dodecahedron micro-crystals were synthesized using coprecipitation and hydrothermal methods. The Na2SO4 as a surfactant was helpful in improving the dispersity of the crystallites and forming well-faceted, micro-sized dodecahedral YAG crystallites. The effect of the reaction time and the solvent has also been studied. The crystal growth mechanism called dissolution/crystallization was determined by analyzing the experimental and simulated results. And the specific well-developed crystal facets in the {110} family have been demonstrated by the theoretical calculation. A higher integrated emission intensity can be achieved for the YAG:Ce crystallites by improving the phase purity, morphology with better developed dodecahedrons, and dispersion. Furthermore, a rather high luminous efficacy (LE = 104.14 lm/W) for the white LED fabricated using the YAG:Ce3+ phosphor prepared in this work was realized. The correlation between the crystal growth, morphology and luminescence properties of YAG crystallites has been established, which exhibits a great importance for the synthesis and application of mono-dispersed YAG crystallites.

Monolayer (ML)-molybdenum disulfide (MoS2) with a direct band gap of ~1.8 eV exhibits considerable potential for advanced electronic and optical device applications. The surface electronic properties of ML-MoS2 need to be controlled for developing novel MoS2-based devices. In this study, we investigated the work function variation of chemical vapor deposition-grown ML-MoS2 that was controlled by proton irradiation. The crystallinity of the ML-MoS2 was confirmed by micro-Raman and Photoluminescence measurements. The work functions of the ML-MoS2 irradiated with varying proton beam flux were measured by Kelvin probe force microscopy. As the ML-MoS2 were exposed to the proton beam flux ranging from 1 × 1012 to 1 × 1014 protons/cm2 at the same beam energy of 10 MeV, the contact potential difference of the MoS2 increased up to about 0.108 V with increased proton beam flux. Based on the referenced value of the Au work function (≈5.1 eV), the work functions of non-treated ML-MoS2 and proton-irradiated ML-MoS2 with a proton beam flux of 1 × 1014 protons/cm2 were determined to be 5.031 eV and 4.992 eV, respectively. The decrease of the work function of the MoS2 with increased proton beam flux is due to the defect formation induced by proton irradiation. We suggest the possibility of engineering the surface potential and electronic properties of ML-MoS2 through controlling proton irradiation conditions.

In this work, we carried out a systematic study of the effects of morphology and coverage of decorated silver (Ag) nanostructures on the sensing performance of monolayer graphene. Ag nanowires (AgNWs) and Ag nanoparticles (AgNPs) were uniformly coated on the chemical vapor deposition-grown graphene. Raman spectra showed that both AgNPs and AgNWs served as n-type dopants to graphene. After decoration of the Ag nanostructures, the sensing performance of the graphene towards NO2 gas at room temperature was significantly improved. For a graphene and AgNWs hybrid sensor, the sensitivity was approximately 2 time higher and the recovery time was ~10 times shorter than the pristine graphene. In addition, we found that the behavior of NO2 adsorption depends on the shape of the decorated Ag nanostructures. The surface coverage ratio of the Ag nanostructures on graphene presented a contrary trend, in that lower coverage of AgNWs and higher coverage of AgNPs on graphene exhibited better sensing properties. The effect of each nanostructure on improving graphene sensing is discussed in terms of the surface energy of different facets of Ag nanostructures and the electronic properties of the hybrid structures.

The Ag2S/CdS composite photocatalyst with a leaf-like structure was synthesized by loading the Ag2S nanoparticles on the surface of the hydrothermally synthesized CdS particles. The UV–Vis–NIR absorption spectroscopy results reveal that the Ag2S/CdS composite photocatalyst exhibits a wide-spectrum response from ultraviolet (UV) to near-infrared (NIR), demonstrating its potential for effective utilization of solar energy. The scanning and transmission electron microscopic observations show that Ag2S nanoparticles with the size of about 20 nm are successfully embedded on the surface of leaf-like structure of CdS. Among the samples loaded with different molar percentages of Ag2S nanoparticles, the 5%-Ag2S/CdS composite photocatalyst exhibits a higher photocatalytic efficiency than the individually synthesized CdS and Ag2S for the degradation of Rhodamine B (RhB) and methyl orange (MO) under LED visible light irradiation. Furthermore, the 5%-Ag2S/CdS composite photocatalyst also exhibits a photocatalytic activity for the degradation of RhB under 850 and 940 nm monochromatic light irradiation. The results of the photocatalytic activity tests performed with various scavengers confirm that ·O2− plays a key role in the photodegradation of RhB. An enhanced photocatalytic performance of the Ag2S/CdS composite photocatalyst is directly attributed to the formation of a heterojunction between Ag2S and CdS. The developed composite photocatalyst can harness a greater share of the solar spectrum from visible to near infrared region and generate the photoinduced charge carriers more efficiently.

Unlike the stretchable physical sensors such as stretchable pressure sensors, strain sensors, and temperature sensors, few works have been reported on the stretchable gas sensors. This study presents that stretchable gas sensors can be fabricated by decorating reduced graphene oxide/silver nanowires (rGO/AgNWs) hybrids on the porous polyurethane (PU) sponges using a facile dip-coating method. The sensors show good room-temperature responses to NO2 gas under both a bending strain (r = 3 mm) and a large tensile strain up to 60%. The response of about −15% is measured at a 50 ppm of NO2 under a 60% strain. Furthermore, reducing gases like acetone and ethanol can also be detected under the large strains. The results of this study offer a new insight into realization of highly stretchable and easy-to-fabricate gas sensors.

Full maximum-entropy mobility-spectrum analysis (FMEMSA) is the best algorithm among mobility spectrum analyses by which we can obtain a set of partial-conductivities associated with mobility values (mobility spectrum) by analyzing magnetic-field-dependent conductivity-tensors. However, it is restricted to a direct band-gap semiconductor and should be modified for materials with other band structures. We developed the modified version of FMEMSA which is appropriate for a material with a single anisotropic valley, or an indirect-band-gap semiconductor quantum-well with a single non-degenerate conduction-band valley e.g., (110)-oriented AlAs quantum wells with a single anisotropic valley. To demonstrate the reliability of the modified version, we applied it to several sets of synthetic measurement datasets. The results demonstrated that, unlike existing FMEMSA, the modified version could produce accurate mobility spectra of materials with a single anisotropic valley.

The flue gas desulfurization wastewater (FGDW) contains extremely high concentration of heavy ions (e.g., Ca2+, Mg2+) and unbiodegradable organic pollutants such as humic substances. In this paper, the effects of softening pre-treatment on water reclamation performance and membrane fouling phenomenon of the direct contact membrane distillation of FGDW were investigated systematically. Results showed that fouling on the membrane caused by crystallization of CaSO4, Mg-Si complex, Al colloid, and organic matter in the FGDW decreased the permeate flux. Pre-treatment with NaCO3, NaOH and polyacrylamide in combination with coagulation and chemical precipitation processes resulted in nearly 100% removal of Ca2+ and Mg2+ and prevented membrane from fouling. This led to 11 times-concentrated FGDW with excellent salt and organic matter rejections. Overall, membrane distillation combined with softening pre-treatment can effectively reclaim FGDW water with high concentration and salt rejection rates, without causing significant membrane fouling.

In this study, we fabricated a novel hybrid photocatalyst (CD-BVO/rGH) by coupling carbon dot (CD)-decorated BiVO4 (BVO) with a reduced graphene hydrogel (rGH). The CD-BVO/rGH photocatalyst significantly enhanced the photocatalytic efficiency for tetracycline hydrochloride (TCH) degradation compared with pure BVO and BVO/rGH under simulated solar irradiation. CD-BVO/rGH also showed a substantial performance in the photocatalytic reduction of CO2. The enhanced photocatalytic activity of CD-BVO/rGH is attributed to synergistic effects, such as better light energy utilization via the upconversion effects of the CDs and the enhanced migration and separation of photoexcited carriers by the three-dimensional (3D) network structure of the rGH. The systematic analysis of the band structure, electron spin resonance, and free radical trapping revealed that h+ and O2– mediate the final photocatalytic degradation of pollutants. Our results provide insight into the design and construction of highly efficient hybrid photocatalysts combined with functional carbon nanostructures to enhance the photocatalytic activity for the photodegradation of environmental pollutants and CO2 reduction.

With the rapid growth of wearable electronics, the development of wearable fuel cells as a smart power source is receiving ever more attention due to their high energy conversion efficiency, modest operating temperature, and ease of handling. To address the most notable limiting factor, the rigid electrodes, of fuel cells, herein, a eutectic gallium-indium liquid metal with excellent deformability and redox ability has been employed to wearable and rechargeable fuel cells with high performance. Thanks to the optimized Ga/In ratio, which is achieved by balancing the anticorrosion and electrochemical activity of the liquid metal anode, the power density of the fuel cell is as high as 72.8 mW cm−2; to our knowledge, this is the highest power density among existing wearable liquid fuel cells at room temperature. Due to the stable redox properties of liquid metal, the fuel cell was stably cycled for 96 h at 2 mA cm−2 as a rechargeable metal-air battery. Meanwhile, running in feed mode to maintain the proportion of Ga in the anode, the fuel cell and the rechargeable liquid metal fuel cell exhibited stable discharging and cycling performances, respectively, and delivered exemplary performances under various flexibility and stretchability measurements. Based on the fluent and renewable liquid metal anode, this novel high-performance wearable liquid fuel cell shows great promise as a shape-variable energy supply for bionic soft robots and wearable devices.

We report a facile method for the synthesis of large-area tungsten disulfide (WS2) films by means of chemical vapor deposition (CVD). To promote WS2 film growth, the precursor solution, which includes pre-reduced tungsten suboxides, is prepared by using hydrazine as the strong reducing agent and spin-coated onto the growth substrate. Growth is then carried out in a CVD chamber vaporized with dimethyl disulfide as the sulfur precursor. Although only WS2 flakes are grown with unreduced tungsten precursors under a hydrogen atmosphere, WS2 films are readily attained on pre-reduced tungsten suboxide substrates without the need for further reduction by hydrogen, which is noted to induce discontinuity of the grown film. The result presents the coverage of WS2 to be proportional to the amount of reduced tungsten suboxides, which is revealed by X-ray photoelectron spectroscopy. Furthermore, it is found that the multilayer WS2 flakes grow along the grain boundary, which allows the analysis of the grain size of WS2 ...

The current work reports on the effect of annealing temperatures on the morphology and photoluminescence properties of SrAl 2 O 4 : Eu, Dy thin films on sapphire (0001) substrates fabricated by pulsed laser deposition technique. Scanning electronic microscopy and atomic force microscopy were used to investigate the thickness, surface topography, and the morphology of the films. The film deposited using a higher annealing temperature was packed with a uniform layer of larger particle size grains. In addition, the surface of this film was shown to be relatively rougher than that without annealing treatment. An intense green emission, which is attributed to the 5 d -4 f transition of Eu 2 + was observed at about 520 nm from the films with annealing treatment. The effects of annealing treatment on the morphology, topography, and photoluminescence properties are discussed in detail.

Polycrystalline Gd 5 Si 3 O 12 N: RE ( RE = Pr, Sm, Eu, Tb and Dy) phosphors have been synthesized via a solid-state reaction method at high temperature, and their photoluminescence properties were studied. The absorption peak at about 230 nm is attributed to the host absorption. For the Pr 3+ -doped sample, the typical excitation lines located at 273 nm originating from the 8 S 7/2 → 6 I J ( J = 5/2, 7/2) transitions of the Gd 3+ ions were observed in the excitation spectra. Upon excitation at 227 nm UV light, the 4 f 1 5 d → 4 f 2 emission band (350–450 nm) and typical 4 f 2 → 4 f 2 emission lines (450–700 nm) assigned to Pr 3+ were observed. The Sm 3+ -doped sample exhibits a bright red emission owing to the 4 G 5/2 → 6 H J ( J = 5/2, 7/2 and 9/2) transitions. However, the charge transfer band of Sm 3+ was not observed in the excitation spectrum. There is a broad band from 200 to 350 nm originating from the charge transfer transition (CT) of the Eu 3+ (O 2− /N 3− → Eu 3+ ) in the excitation spectra, and the strongest peak in the emission spectra located at 615 nm is due to the electric-dipole 5 D 0 → 7 F 2 transition of Eu 3+ . For the Tb 3+ -doped sample, it shows 5 D 3 → 7 F J ( J = 5, 4, 3, 2) blue line emissions and 5 D 4 → 7 F J ( J = 6, 5, 4, 3) green line emissions under the excitation of Tb 3+ . The Dy 3+ -activated sample upon excitation at 349 and 386 nm UV light shows blue-green and orange-red emission lines originating from 4 F 9/2 → 6 H J ( J = 15/2, 13/2) transitions. In addition, the energy transfer from the host lattice to the luminescence activators (i.e. Pr 3+ , Sm 3+ , Eu 3+ , Tb 3+ , Dy 3+ ) has been confirmed. In addition, the energy level diagram including the 4 f and 5 d energy levels of all Ln 2+ and Ln 3+ ions relative to the valence and conduction band of Gd 5 Si 3 O 12 N were constructed and discussed.

In this work, graphitic carbon nitride (g-C 3 N 4 ) nanosheets were prepared and employed to improve the gas sensitivity performance of graphene. g-C 3 N 4 nanosheets (NS-CN) were exfoliated from bulk powder using a proton-enhanced liquid-phase exfoliation method, where the co-ordinate bonds between nitrogen of g-C 3 N 4 and proton H + of HCl benefit the swelling of bulk and improve the delamination process. The thickness and size of the exfoliated nanosheets were about ∼4 nm and 1–2 μm, respectively. A slight increment of the bandgap of g-C 3 N 4 was observed after exfoliation. It was found that the proton functionalization of g-C 3 N 4 powder before exfoliation facilitates the production of uniform nanosheets. A certain amount ranging from 0% to 90% of as-prepared g-C 3 N 4 was added to a graphene solution and ultrasonically mixed to prepare a graphene/g-C 3 N 4 nanocomposite (G/NS-CN). The performances of pure graphene-based and nanocomposite-based sensors in sensing NO 2 gas were systematically investigated and compared. We found compositing g-C 3 N 4 with graphene significantly enhanced the sensing performance of the graphene sensor. A trade-off effect on sensing response was observed as the weight ratio of NS-CN to graphene in the nanocomposite sensor was changed, suggesting the specific roles of g-C 3 N 4 and graphene in sensing behavior. It was found that the nanocomposite sensor with 15 wt% of NS-CN exhibited the best sensing response. The sensor in this optimized composition presented a linear and stable response as well as good recovery toward NO 2 gas. The sensing mechanism of the nanocomposite sensor was also proposed.

Despite the great potential of zinc oxide (ZnO) nanostructures as a sensing material for high-performance gas sensors, the correlation between the morphology of ZnO nanostructure and its gas-sensing performance has not been systematically investigated yet. In this work, ZnO nanostructures with controlled morphologies were synthesized by low-temperature solution route and chemical bath deposition method. Thin film gas sensors were fabricated from the nanostructures and the sensor performance such as the response, recovery time, and stability was examined for several gases. It is demonstrated that the gas-sensing performance of a ZnO nanostructure sensor is strongly influenced by its morphology. One dimensional ZnO nanocones are highly promising for practical application to gas sensors, due to their large surface area per unit mass and unique conical structure.

This study employed experimental results and theoretical calculations to investigate Mn-adsorbed g-C3N4 as a potential photocatalyst with high efficiency. Mn was chosen as the incorporating element, because among the 3d transition metals it exhibits the highest binding energy and most suitable band edge positions. The photocatalytic efficiency of Mn-adsorbed g-C3N4 is 3 times higher that of pristine g-C3N4. Although small variations in the phase and surface morphology were observed, which were confirmed to not be the determining factors to improve efficiency. The factors that affect the high photocatalytic efficiency are therefore the electronic structure, optical absorption, and band edge variations after Mn-adsorption. The Mn atoms stably are bonded with N atoms, due to the strong absorption energy and ionic bond. Moreover, reduction of the g-C3N4 band gap after Mn-adsorption results in a red shift of the absorption band edge. The half-filled Mn 3d state introduces impurity states into the forbidden band gap, which will increase the life time of charge carriers. In addition, the up-shifting of band edges of Mn-adsorbed g-C3N4 leads to inhibition of the electron-hole recombination. As a consequence, the photocatalytic efficiency of Mn-adsorbed g-C3N4 is enhanced due to the combination of the aforementioned effects.

We report on the synthesis of large-area molybdenum disulfide (MoS2) film on an insulating substrate by means of chemical vapor deposition. A single mixture of molybdenum hexacarbonyl (Mo(CO)6) and dimethyl disulfide (C2H6S2) was utilized as an organic liquid precursor for the synthesis of MoS2 film. Carbon impurities stemming from the dissociation of the organic precursor are effectively removed by water oxidation, and hydrogen gas, which is a by-product of the oxidation of carbon impurities, inhibits the formation of molybdenum oxides. The use of a liquid precursor assisted with water oxidation ensures high reproducibility and full-coverage of MoS2 film for large area, which is not typically achieved with solid precursors such as molybdenum oxide and sulfur powder. We believe that our approach will advance the synthesis of transition metal dichalcogenides.

Blue-emitting phosphors (Gd 1- x Ce x ) 5 Si 3 O 12 N (0 ≤ x ≤ 0.07) were prepared through a solid-state reaction under a reducing atmosphere. The excitation spectra exhibited several broad bands in the wavelength range from 240 to 400 nm, and the emission spectra consisted of a broad band covering from 360 to 550 nm. Two different emission centers corresponding to two different crystallographic sites in the host lattice were confirmed. The influence that the Ce 3+ concentration had on the photoluminescence of the prepared samples was examined, and the results indicate that an increase in the Ce 3+ concentration introduces a red-shift of the emission peak due to an increase in the Stokes shift. Concentration quenching occurs when the Ce 3+ content exceeds 3 mol%. In addition, the configurational coordinate model was used to finely explain the thermal quenching behavior of the phosphors.

Additional file 1: Fig. S1. DAPI nuclear stain of a normal cell (MCF10A) and breast cancer cells (MCF MCF7, T47D, MDA-MB-231). Blue is DAPI nuclear stain, which shows that there is only one nucleus per cell. Fig. S2. Linear regression analysis between (A) Young’s modulus and F-actin/area, and (B) physical adhesion and Integrin/boundary length. A high correlation can be found in adjusted R-squared of 0.92167 and 0.97347 for the relations, respectively.

The novel green luminescent material of the semiconductive nanoporous ZnMnO thin film was fabricated by grain boundary engineering and thermal stress engineering via the thermal nucleation of the sputter-grown ZnMnO layers. Nanoporous ZnMnO exhibited the strong green luminescence characteristics, attributing to the photon confinement at the localized green-emission band formed near the edge area of ZnMnO nanopores. Using semiconductive nanoporous ZnMnO, two different types of high-performance solid-state lighting devices (i.e., field emission device and light-emitting diode) were demonstrated as tangible applications of semiconductive nanoporous ZnMnO.

In this work, we have investigated the variation of internal electric field of 4-period In0.16Ga0.84N/pseudo-AlInGaN multiquantum wells (MQWs) embedded in p-i-n structure by surface acoustic waves (SAWs). The pseudo-AlInGaN barriers consist of two In0.16Ga0.84N(11 A) sandwiched by three Al0.064Ga0.936N (15 A). The equivalent indium and aluminum compositions in pseudo-AlInGaN barrier are 0.043 and 0.052, respectively, which can be calculated by volume ratio. For reference purpose, In0.16Ga0.84N/GaN MQWs was also used. To generate surface acoustic wave, interdigital patterns with 1 μm finger width were fabricated by e-beam lithography. The piezoelectric fields for GaN barrier and pseudo- Al0.043In0.052Ga0.905N barrier samples are found to be 1.5 MV/cm, 0.33 MV/cm from bias-PL. From μ-PL measurement for pseudo-Al0.043In0.052Ga0.905N barrier sample, we observed lowest luminescence intensity at 100 MHz and 13 dBm in radio frequency (RF) generator, which means that electron-hole recombination can be suppressed by SAWs. The Photocurrent measurement for pseudo-Al0.043In0.052Ga0.905N barrier sample was observed increasing around 2 orders of magnitude at 100 MHz when compare to GaN barrier sample. Based on our results, the reduced piezoelectric field added to SAWs can be provided one of the solutions for enhancing photocurrent in III-nitride photovoltaic devices by extract carriers from quantum wells easily and enhancing traveling length of carriers.

Separation of refined silicon from Al&ndash, Si melt is still a puzzle for the solvent refining process, resulting in considerable waste of acid and silicon powder. A novel modified Czochralski method within the Al&ndash, Si alloy is proposed. After the modified Czochralski process, a large amount of refined Si particles was enriched around the seed crystalline Si and separated from the Al&ndash, Si melt. As for the Al&ndash, 28%Si with the pulling rate of 0.001 mm/min, the recovery of refined Si in the pulled-up alloy (PUA) sample is 21.5%, an improvement of 22% compared with the theoretical value, which is much larger 1.99 times than that in the remained alloy (RA) sample. The content of impurities in the PUA is much less than that in the RA sample, which indicates that the modified Czochralski method is effective to improve the removal fraction of impurities. The apparent segregation coefficients of boron (B) and phosphorus (P) in the PUA and RA samples were evaluated. These results demonstrate that the modified Czochralski method for the alloy system is an effective way to enrich and separate refined silicon from the Al&ndash, Si melt, which provide a potential and clean production of solar grade silicon (SoG-Si) for the future industrial application.

We materialized room-temperature ferromagnetism in ultrathin α-MoO

In this study, we report the construction of a novel composite photocatalyst (BiVO4/rGH) composed of quantum dots (QDs) self-decorated BiVO4-nanoparticels (NPs) and reduced graphene hydrogel (rGH). The composite structures were prepared using an in-situ growth method. The BiVO4/rGH composite photocatalysts exhibited excellent photocatalytic efficiency for the degradation of tetracycline hydrochloride (TCHCl). The promoted photocatalytic activity of the BiVO4/rGH is attributed to the synergetic effects of the unique structure involving QDs self-decorated BiVO4 NPs and a 3D network structure of rGH, which resulted in higher number of photogenerated charge carriers, surplus active sites, and enhanced charge separation. In addition, trapping measurements showed that ·O2- and h+, as the main active species, play a crucial role in the degradation of TCHCl over the composite photocatalyst. This study facilitates the design and construction of high efficiency hybrid photocatalysts with multifunctional materials for the removal of water pollutants.

The efficient removal of antibiotics in water is essential to protect aquatic environment as antibiotics are some of the most hazardous pollutants in water. Herein, we report the synthesis of a novel N-GNDs/Ag/BiVO4 ternary photocatalyst consisting of BiVO4 coupled with Ag nanoparticles (Ag-NPs) and nitrogen-doped graphene nanodots (N-GNDs) to degrade and mineralize tetracycline hydrochloride (TC•HCl) in water. The ternary photocatalyst shows higher photocatalytic degradation of TC•HCl under full spectrum light than pure BiVO4. Based on the morphology, crystalline structure, physicochemical properties, and photoelectrochemical behavior of the ternary photocatalyst, the enhanced photocatalytic performance is attributed to the upconversion effect of N-GNDs and the localized surface plasmon resonance (LSPR) effect of Ag-NPs. Thus, the synergetic effects expand the absorption range of light and significantly promotes the separation of photoexcited carriers. Further, a possible photocatalytic reaction mechanism of TC•HCl degradation over N-GNDs/Ag/BiVO4 is discussed via through investigation of the charge carrier migration, active species, and intermediates in the degradation processes.

Membrane wetting and fouling represent the foremost concerning issues confining membrane distillation in the treatment of industrial wastewater. This work presents a superhydrophobic poly(vinylidene fluoride) (PVDF) membrane with anti-fouling property, which was derived from the bioinspired adhesive, mineralization and fluorination process for the direct contact membrane distillation (DCMD). The synthesis of membrane was initiated by co-depositing polydopamine/polyethylenimine composite layer onto membrane substrates as “bio-glue” associated with β-FeOOH nanorods as hierarchical structure anchoring to form coordination complexes via the catechol group and Fe3+, then proceeded with the fluorination of 1H,1H,2H,2H-perfluorodecyltriethoxysilane to obtain the superhydrophobic PVDF membrane. Due to the unique micro-nano structure obtained, the resulting PVDF membrane, with a low sliding angle of 5.7° and a high water contact angle of 162°, conforms to the Cassie state. The membrane morphology, wetting behaviour, and anti-fouling performance were systematically characterized. The novel mineralized superhydrophobic membrane exhibited a steady flux and an outstanding salt rejection (99.9%) in treating high salinity and hardness containing-wastewater during 60-h-DCMD test, thus showing great potential for practical application in long-term DCMD.

BiOCl:Eu3+ ultrathin nanosheets were synthesized through a facile solvothermal method with the assistance of polyvinyl pyrrolidone. The ultrathin nanosheets showed a size ranging from 50–100 nm and a height of 2.9 nm, which is about four [Cl–Bi–O–Bi–Cl] layers. In addition, the luminescence properties and mechanism were investigated in detail, and compared with that of the nanoplate. It was found that the luminescence intensity for the BiOCl:Eu3+ ultrathin nanosheet was 6 times stronger than that of the nanoplate. Importantly, the oxygen vacancies act as a luminescence centers, and there was effective energy transfer from BiOCl ultrathin nanosheets to Eu3+ ions. In BiOCl:Eu3+ ultrathin nanosheets, white-light emission was observed under near-ultraviolet (NUV) excitation. These BiOCl:Eu3+ ultrathin nanosheets exhibit great potential as color-emitting phosphors for white light-emitting diode applications.

Three-dimensional flower-like Eu3+ and Sm3+-activated BiOCl globular microarchitectures were synthesized by the solvothermal method employing urea as a dispersing agent for the first time. The crystal structure, morphologies and luminescence properties of Eu3+ and Sm3+ doped BiOCl have been systematically investigated by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) and spectroscopy, respectively. The unit cell volumes show a nearly linear decrease by about 0.18 and 0.15% with increasing Eu3+ and Sm3+ concentration up to 9 mol%, respectively. All of the prepared samples show flower-like globular microarchitectures with an average diameter about 3–5 μm with different Eu3+ and Sm3+ concentrations. Possible formation mechanism for the flower-like microarchitectures is proposed on the basis of time-dependent experiment. Both BiOCl:Eu3+ and BiOCl:Sm3+ samples show a strong red emission corresponding to the 5D0 → 7F4 transition (700 nm) of Eu3+ and 4G5/2 → 6H7/2 transition (600 nm) of Sm3+, respectively. This work sheds some light on the design and preparation of red-emitting phosphors with novel microstructures.

We have investigated the effect of laser irradiation on monolayer MoS2 and observed the swellingup of the monolayer from the SiO2 substrate upon laser illumination. The mismatch in the thermal expansion between the substrate and MoS2 can result in the structural deformation. Employing this method, one can induce structural deformation in a desired pattern, and one can demonstrate the patterning of periodic ripples in monolayer MoS2 by using laser irradiation. The controlled fabrication of the ripple structure may be instrumental in understanding the effect of ripples on the interesting physical properties of monolayer MoS2.

The electronic structure and the optical properties of Mn-decorated graphitic carbon nitride (g-C3N4) were investigated using the density functional method. The large absorption energy of the Mn atoms on the g-C3N4 surface was found to suppress the clustering of the Mn atoms, which led to a conservation of the photocatalytic activity. The electronic structures of the Mn-decorated g-C3N4 showed that impurity energy levels emerged in the forbidden band of g-C3N4 and that the band edge of g-C3N4 shifted upward to 0.40 eV. In addition, the calculated optical constants showed that the novel photon absorption in the range of visible light originated from electronic transitions from the N 2p states in the upper valence band to impurity Mn 3d states. Moreover, the photon absorption reached a maximum when all sites of triangular N holes were decorated with Mn atoms. Our results provide evidence that the Mn-decorated C3N4 system could be a highly-efficient photocatalyst for solar light due to the extension of the range of photon absorption to include almost all visible light.

Ti-decorated graphitic carbon nitride (g-C3N4) monolayer as a promising material system for high-capacity hydrogen storage is proposed through density functional theory calculations. The stability and hydrogen adsorption of Ti-decorated g-C3N4 is analyzed by computing the adsorption energy, the charge population, and electronic density of states. The most stable decoration site of Ti atom is the triangular N hole in g-C3N4 with an adsorption energy of −7.58 eV. The large diffusion energy barrier of the adsorbed Ti atom of ∼6.00 eV prohibits the cluster formation of Ti atoms. The electric field induced by electron redistribution of Ti-adsorbed porous g-C3N4 significantly enhanced hydrogen adsorption up to five H2 molecules at each Ti atom with an average adsorption energy of −0.30 eV/H2. The corresponding hydrogen capacity reaches up to 9.70 wt% at 0 K. In addition, the hydrogen capacity is predicted to be 6.30 wt% at 233 K and all adsorbed H2 are released at 393 K according to molecular dynamics simulation. Thus, the Ti-decorated g-C3N4 monolayer is suggested to be a promising material for hydrogen storage suggested by the DOE for commercial applications.

Two-dimensional (2D) hexagonal boron nitride (h-BN) is a thin insulating material that can be used to enhance the electrical and optical properties of other 2D materials when used as a substrate or a capping layer, owing to its absence of dangling bonds on the surface. The use of multilayer h-BN films is often required in such applications to realize high material performance. However, previous works have focused mostly on the synthesis of monolayer or few-layer h-BN films. Herein we report a method to control the thickness of h-BN film up to the centimeter scale by means of plasma-enhanced chemical vapor deposition (PECVD). The thickness of the h-BN film is controlled by varying the deposition time of borazine precursor onto a monolayer h-BN film on a Pt foil substrate at room temperature. The resultant film is then annealed at high temperature (1050 °C) to increase the crystallinity of the h-BN. Monolayer h-BN film grown on Pt foil used as a buffer layer is of importance to improve uniformity and smooth surface of the multilayer h-BN film over the whole area. We further demonstrate that our multilayer h-BN film is very useful in graphene/h-BN/SiO2 heterostructures as a charge-blocking layer between graphene and SiO2.

Elastic and tensile properties of mixed-anion oxysulfide CaZnOS have been theoretically investigated by first principle method of density functional theory (DFT). Elastic constants were obtained by stress–strain relationships, and bulk structure parameters including bulk modulus, shear modulus, as well as Poisson's ratio were then calculated using Voigt-Reuses-Hill (VRH) approximation. The results of shear anisotropic factors, compressibility anisotropic factor and directional Young's modulus showed that CaZnOS is almost elastically isotropic in {001} planes and maintains elastic anisotropy in {100} or {010} planes. Chemical bond anisotropy shown by Mulliken atomic charges and bond overlap populations is responsible for the elastic anisotropy behavior aforementioned. Moreover, theoretical uniaxial and biaxial tensile results showed the crystal collapsed at strain more than 12%, except in the biaxial extension where CaZnOS collapsed at strain of 7%.

The two key factors such as light adsorption and separation of charge carriers in photocatalysts play crucial roles in determining the overall photocatalytic efficiency. Herein, we report synergetic effects of Fe-doping and Au nanoparticles (Au-NPs) deposition on the photocatalytic activity of the modified Bi4O5Br2 (BOB) nanosheets photocatalyst for Bisphenol A degradation and gaseous NO oxidative removal. Fe-doped BOB nanosheets decorated with Au-NPs are synthesized by a two-step chemical method. It was found that the Fe-doped BOB sample decorated with Au-NPs (Au-Fe-BOB) exhibits higher photocatalytic activity than the BOB, Fe-doped BOB, and Au-NPs-loaded BOB samples. Internal Fe-doping in the BOB enhanced the visible light absorption and the separation efficiency of photogenerated charge carriers acting as a scavenger. Moreover, the decorated Au-NPs in the composite photocatalyst extended the light adsorption in the range of visible and near- infrared light due to surface plasmon resonance effect of Au-NPs. The spin trapping measurements of Au-Fe-BOB composite photocatalyst show that the •O2− is a main reactive species during the photocatalytic reaction under visible-light irradiation. The excellent photocatalytic efficiency and stability of Au-Fe-BOB with visible-light response allow to be readily constructed and applied for practical removal of various pollutants using solar light in the future.