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Meeting the growing demands of attaining clean water regeneration from wastewater and simultaneous pollutant degradation has been highly sought after. In this study, nanometric CuFe2O4and plasmonic Cu were in situconfined into graphitic porous carbon nanofibers (CNF) through electrospinning and controlled graphitization, which were integrated onto a melamine sponge (S-FeCu/CNF) as a monolithic evaporator viaa calcium ion-triggered network crosslinking method using sodium alginate (SA). This monolithic evaporator serves a dual purpose: harnessing solar-driven photothermal energy for water regeneration and facilitating synchronous contaminant mineralization through advanced oxidation processes (AOPs). The metal-modified FeCu/CNF graphitic porous carbon exhibited an enhanced light absorption property (≥95%) and was further securely anchored on the sponge by a calcium ion-triggered SA crosslinking technique, thereby efficiently restraining salt deposition. The FeCu/CNF evaporator demonstrated a solar-vapor conversion efficiency of 105.85% with an evaporation rate of 1.61 kg m−2h−1under one sun irradiation. The evaporation rate of the monolithic S-FeCu/CNF evaporator is close to 1.76 kg m−2h−1, and an evaporation rate of 1.54 kg m−2h−1can be achieved even in 20% NaCl solution, with resistance to salt deposition and cycling stability. Synchronously, the monolithic D-S-FeCu/CNF evaporator also acts as a heterogeneous catalyst to activate peroxymonosulfate (PMS) and trigger rapid pollutant degradation, which also shows excellent catalytic cycling stability, producing clean water that satisfies the World Health Organization (WHO) standards. This work provides a potentially valuable solution for addressing desalination and wastewater treatment.

Due to its potential applications as a high-energy density material, the high-pressure polymorphs of ammonium azide (AA) have received much attention recently. However, the crystal structure of phase II (AA-II), stable above 3.0 GPa, has remained elusive until now. By combining X-ray diffraction and Raman experiments with first-principles calculations, we determine that AA-II is a hydrogen (H)-bonded structure of ammonium and azide ions with monoclinic symmetry, space group P2/c. The latter is comprised of alternating molecular layers of ammonium and azide ions and mostly differs from AA-I by its denser packing of molecular planes while preserving the hydrogen bond network. First-principles calculations show that phase II has the lowest enthalpy among all other considered structures from 4.9 to 102.6 GPa, pushing the phase transitions to the previously predicted hydronitrogen solids to higher pressures. Raman data to 85.0 GPa at room temperature confirm the absence of phase transition and agree very well with the pressure evolution of the Raman modes of AA-II predicted by our calculations.

The effect of high pressure on the phase transition behaviors of 4-toluenesulfonyl azide (C7H7N3O2S, 4-TsN3) have been investigated by Raman scattering and angle-dispersive X-ray diffraction (ADXRD) measurements in diamond anvil cells up to ∼15.6 GPa at room temperature. The liquid 4-TsN3(phase I) begins to transform into solid state (phase II) at 0.7 GPa, and turns to phase III at about 2.7 GPa, then going to phase IV at about 6.3 GPa. The phase IV of 4-TsN3finally starts to turn into an amorphous state above 10.6 GPa. The first phase transition (phase I to phase II) of 4-TsN3is triggered by the rearrangement of CH···π interaction, and the second phase transition (phase II to phase III) is attributed to the conformational change, then the rotation of sulfonyl leads to the third phase transition (phase III to phase IV). The variation of sulfonyl has an influence on the behavior of azide group which will bend and further decompose upon compression. In the process of amorphization, the lattice structure of 4-TsN3abnormally expanded, which may be caused by the change of CH···π interactions. We anticipate that the high pressure study of 4-TsN3provides information toward further understanding and optimizing synthesis conditions of the polymeric nitrogen using azides as starting materials, especially using organic azides.

Cd2(C2H6N6)4(NO3)4·H2O (CdHATr), a triazole-based energetic compound, was selected for high-pressure research. Employing in situ Raman scattering and synchrotron angle-dispersive X-ray diffraction (ADXRD) technologies, this study investigated CdHATrup to ∼16.3 GPa at room temperature. The vibrational modes of CdHATrat ambient pressure were comprehensively resolved based on the experimental results. Detailed spectral analyses revealed that CdHATrunderwent three pressure-induced phase transitions at 0.5, 2.2, and 5.2 GPa. ADXRD experiments confirmed the presence of these phase transitions, as observed in Raman spectral analyses. By analyzing the changes of the vibrational spectra and the lattice parameters under pressure, it is suggested that the first phase transition arises from the deformation of the 3-hydrazino-4-amino-1,2,4-triazole (HATr) ligand, the second phase transition results from the rearrangement of hydrogen bonds, and the third phase transition is caused by the conformational change of the triazole ring. ADXRD results show that CdHATrmay experience an abnormal expansion at 0.5 GPa, which is probably caused by the deformation of the HATr ligand. This work contributes to the understanding of the structures of triazole-based energetic compounds under pressure, which will help in the synthesis of new compounds in the future.

Photothermal nanomaterials have showed great potential for development in simultaneous pollutant purification and freshwater recovery. In this study, a novel composite composed of hollow N-doping SiC porous hybrid network with the integration of CoCu bimetal species was constructed by a simple self-assembly and temperature-modulated approach. Such a hollow porous hybrid nanoreactor is endowed with abundant synergetic CuCo bimetallic reactive sites and polar pyrrolic N sites, which improves the enrichment of pollutants and intermetallic redox pairs. Ultrafine nanocrystals corresponding to Co2SiO4over the hybrid framework can be evidenced by HRTEM technique. The experimental results showed that the optimal CoSiCu-6 degraded norfloxacin (NFX) by 90.7% in 10min with a pseudo-first-order rate constant of 0.493min-1, which was about 6.49 folds enhancement compared to Cu-free CoSi-6 counterparts, achieving a low reaction activation energy (18.02kJmol-1) during the reaction. Control experiments including anion interference and broad applicability for pollutants degradation were further explored, emphasizing the excellent performance of CoSiCu-6 in the practical contaminant removal. The mechanism study showed that, single linear oxygen (1O2) coupled with electron-transfer process work as the main activation routes dominating the degradation process. In addition, Co3+/Co2+/Cu2+redox pairs and oxygen vacancies (Ov) play a key role in the PMS activation process. The obtained optimal catalyst was further explored for solar-driven photothermal interfacial water evaporation, showing a rational cleanwater recovery efficiency (~1.3kgm-2h-1) from the polluted wastewater. In addition, monolith floatable evaporator was constructed by anchoring CoSiCu-6 onto a tailored melamine sponge foam via a calcium ion-triggered sodium alginate cross-linking strategy, affording an excellent evaporation performance (2.16kgm-2h-1) and coupled norfloxacin degradation efficiency (93.6%, within 5min). This innovative monolithic evaporator made of CoCu integrated SiC hybrid nanosphere has a powerful dual function of rapidly degrading pollutants and facilitating solar-powered regeneration of contaminated wastewater due to its unique hollow porous structure and the CoCu bimetallic synergistic action that provides a rich set of reaction sites, which is promising for the treatment of complicated wastewater.

Here, we present the synthesis of all-inorganic mixed-halide CsPb(Br_1−xI_x)_3 nanocrystals with color-tunable emission (464–667 nm) having narrow emission line-widths (23–47 nm); we synthesize the nanocrystals in an ambient atmosphere by employing a newly reported saponification process in our laboratory. This inert gas-glovebox-free protocol synthesis technique offers simplicity and low cost in the preparation of high-quality nanocrystals. Notably, nanocrystals with different emission wavelengths resulted in tunable correlated-color temperature (2513–9783 K) while maintaining a high color rendering index (up to 95), desirable for white light. Thus, the experimental results suggest that the nanocrystals obtained by the saponification process in this work can be used for future indoor illumination.

Saponification approach was employed to synthesize all-inorganic halide perovskites at an ambient atmosphere. We report the conversion from CsPbBr3to lead-depleted Cs4PbBr6crystals by varying the amount of Cs-oleate precursor at room-temperature synthesis. This transformation drastically changes the morphology as well as the structure and hence the optical properties of the perovskites. The cubic CsPbBr3nanoplatelets with a strong blue emission (462 nm) attenuate a green (529 nm) emission when the material crystallizes in the rhombohedral phase (Cs4PbBr6), which demonstrates the intrinsic luminescence nature of the Cs4PbBr6crystals. In addition, we proposed to combine these two compounds with the yellow- and red-emitting perovskites to generate white light emission. The correlated color temperature is tuned from 2480 to 9134 K and the color rendering index (CRI) is maximized up to 96, the highest CRI yet known for these types of materials. These characteristics demonstrate the high potential to replace conventional phosphors in lighting devices.

In the present work, hot deformation behaviors of FB2ultra-super-critical rotor steel are investigated by isothermal compression tests under the deformation temperature range of 1323–1473 K and strain rate range of 0.01–1 s−1. The microstructure evolution of the deformed samples and the nucleation mechanism of dynamic recrystallization are studied by using electron backscatter diffraction and transmission electron microscopy. The results show that: (1) when the strain rate is higher than 0.1 s−1and the temperature is lower than 1373 K, it easily results in a large number of substructures with relatively low-angle boundaries due to the intense work hardening effect. (2) Discontinuous dynamic recrystallization characterized by grain boundary bulging is the dominant nucleation mechanism for the studied rotor steel. (3) Geometrically necessary dislocations are sensitive to strain rate for the studied rotor steel but is less sensitive to the deformation temperature. (4) The low-angle boundaries fraction slightly increases with the increase in the Zener–Hollomon (Z) parameter under the test conditions.

We report on a new synthesis process for halide perovskite nanoplatelets and nanoplates that switches the production process of the cesium precursor from a fatty acid/cesium salt reaction to a cesium base/fatty acid ester reaction, thus enabling the reaction to occur in ambient conditions in minutes instead of hours. The saponification precipitation process reported here, as a result, does not require a vacuum oven or inert reaction environment in obtaining the cesium precursor, or any part of the reaction. Furthermore, the process creates a hygroscopic byproduct that results in a self-drying synthesis. The obtained perovskite nanocrystals exhibit a blue-green tunable emission that occurs via a quantum confinement effect, phase, and morphology change. The consequence of these physical processes is that the band gap is highly tunable with temperature and the resulting nanocrystals show remarkable optical properties, while greatly simplifying the production of halide perovskite nanoplatelets and nanoplates.

A naked cyclo-N5–salt has yet to be recovered to ambient conditions, precluding its application as a high-energy density material for explosive or propulsion applications. Here, we suggest a simple route for the synthesis of a metal cyclo-N5–salt via compressing CuN6. Using first-principles calculations with structural search, we predict a CuN5compound with a cyclo-N5–anion that is energetically favorite in the pressure range of 50–100 GPa. At ambient conditions, CuN5comprises alternant-connected cyclo-N5–anions and Cu+ions, forming a zigzag chain. The copper cyclo-N5–salt is thermodynamically stable with a 2.5 eV band gap at ambient conditions. Further analysis of electronic properties reveals that the Cu atoms not only contribute electrons to change the bonding state of N5rings but also use empty outer-shell orbitals to accommodate lone pair electrons of N atoms, forming coordinate bonds to stabilize the system. This expands the known cyclo-N5–salt and indicates a simple route to its synthesis.

Ultraviolet (UV)-green emitting MAPbBr3nanocrystals were synthesized at room temperature, employing a cost-effective solution-based method. The size control of nanocrystals was achieved through varying ligand and solute concentrations, which resulted in a tunable band gap and emission spectrum. The growth mechanism as well as the effect of ligand concentration on the structural and optical properties were studied in detail. The excitation spectra extended from the blue to UV region. This indicates that these perovskites are promising photon down conversion materials, which can combine with III-nitride UV/blue light-emitting diodes (LEDs) to emit white light. This work may bring III-nitride-based white LEDs one step closer to widespread adoption in general illumination market because the large emission range that has been produced with the ligand-assisted reprecipitation process is an important milestone in the path to justifying commercialization.

Photothermal catalysis of functional materials triggered by light-irradiation to local heating approach attracts growing attention, but one key detail affecting catalytic thermodynamic process was often ignored that thermal-conductive surface of functional materials directly contacting reaction solution easily delivers heat to the reaction system, leading to weakening heating effect in the interfacial local catalytic microenvironment. Herein, a functional low-thermal-conductivity layer that Mn-coupling porous SiO2shell layer was constructed over the Co3O4nanospheres. Specifically, SiO2with porous channels introduced acts as the thermal-insulation layer to prevent the heat dissipation of the photo-heating core of Co3O4. More importantly, porous channel and inserted MnOxactive species could further offer an additive special reaction microenvironment over the photo-heating core of Co3O4. Additionally, the introduction of Mn and structural remodeling through tailored annealing temperature (600–800 °C) can give improved catalytic hybrids abundant valence states and interfacial effects. A series of Co@Mn/m-SiO2catalysts were fabricated based on the above control tactic. The Co@Mn/m-SiO2catalysts exhibit superior activating ability for peroxymonosulfate (PMS) to degrade bisphenol A (BPA) and other pollutants including 2, 4-dichlorophenol (2, 4-DCP), phenol (PhOH), oxytetracycline (OTC), and tetracycline (TCN). Specifically, Co@Mn/m-SiO2-700 was shown to achieve complete degradation of 20 ppm BPA in less than 10 min under optimal conditions. In addition, we demonstrated that functional silica layer modified Co3O4affords a better photo-heating effect compared to bare Co3O4sphere in air or water, thereby contributing to a faster PMS activation efficiency. Besides, thermal treatment processing for Co@Mn/m-SiO2catalyst makes the surface reactive species be optimized to generate more beneficial redox pairs and reach excellent photothermal catalytic efficiency in various pollutants treatment.

An integrable matrix nonlinear Schrödinger (NLS) equation on a star graph with semi-infinite incoming and outgoing bonds are presented by attaching a matrix NLS equation to each bond. We demonstrate that the matrix NLS equation on star graphs has infinitely many constants of motion and is a completely integrable system by establishing a link between the solutions of the matrix NLS equation on each bond and those of the standard matrix NLS equation on a line. On star graphs, novel symmetry-dependent connection conditions of the vertex for the matrix NLS equations are put forth.

In this work, we present the effects of high pressure on the structure and stability of cesium azide (CsN3) with the pressure up to ∼30.0 GPa, as studied by Raman and IR spectroscopy. Three phase transitions of Phase II → III → IV → V were revealed at ∼0.5, ∼3.7, and ∼16.0 GPa. The abnormal softening behavior of T(Eg) mode reveals the shearing distortion during Phase II → III transition. Moreover, changes of lattice modes and splitting of the degenerate T(Eg) and R(Eg) modes in Phase III indicate the breaking of crystallographically equivalent condition of azide ions. Phase IV was found to possess the C2/mstructure, and Phase V has a lower symmetry structure than other phases. The IR measurements show the evolution of the NNN bending modes and the IR-active behavior of the symmetric stretch ν1mode under pressure, which collectively reveal the rotation and bending of the azide ions upon compression. The azide ions groups were found to further bend under pressure, and the bent azide ions might enhance propensity of nitrogen polymerization.

The in situhigh-pressure phase transition behaviors of energetic material 4-carboxybenzenesulfonyl azide (C7H5N3O4S, 4-CBSA) have been investigated by the measurements of Raman scattering, mid-IR absorption, and angle-dispersive X-ray diffraction (ADXRD) in diamond anvil cells, the highest pressure in our studies was up to ∼14.6 GPa at room temperature. 4-CBSA transforms from phase I into phase II around 0.5–0.9 GPa, and then starts to going to phase III at about 2.5 GPa, phase II coexists with phase III until to about 5.5 GPa, the phase III of 4-CBSA finally begins to transform into amorphous state above 10.5 GPa. The first phase transition (phase I–II) of 4-CBSA is induced by the change of molecular conformation, and the second phase transition (phase II–III) is attributed to the distortion of benzene ring and the change of intermolecular O–H···O hydrogen bonds. The existence of sulfonyl group makes it much easier for the bent azide group to decompose under high pressure, which interpret that the amorphization pressure in 4-CBSA is much lower than that in benzyl azide. The unique behavior of the azide group may be helpful to understand the electron orbit hybridization and the formation of polymeric nitrogen.

Strontium azide (Sr(N3)2) has been studied by in situhigh pressure X-ray diffraction at room temperature. Sr(N3)2exhibits anisotropic compressibility due to the orientation and rotation of azide anions. The refinement results and spectra measurements reveal that Sr(N3)2possesses bent azide ions at ambient conditions, differing from the linear azide ions of alkali azides. The bent azide ions further bend and rotate with increasing pressure. These unique properties of bent azide ions play a significant role in the process of electron orbit hybridization and greatly enhance the propensity of nitrogen polymerization. The bulk modulus of Sr(N3)2is 49.1 GPa, which is larger than those of alkali azides and close to those of heavy metal azides. The larger bulk modulus is attributed to the partial covalent bonding character of Sr(N3)2. Sr(N3)2transforms into an amorphous phase at relative low pressure compared with alkali azide. This property might induce that Sr(N3)2transforms into polymeric nitrogen more readily than other inorganic azides.

Synchrotron X-ray diffraction (XRD) is performed on BaF2nanoparticles to study the structural phase transition up to about 30 GPa under ambient temperature. We observed that the cubic structure in BaF2nanoparticles is stable up to 6.8 GPa, a level much higher than that in bulk BaF2. Pressure-induced amorphization (PIA) occurs in BaF2nanoparticles under compression, which results in a high-density amorphous (HDA) form. Upon pressure release, a low-density amorphous (LDA) form is maintained at ambient conditions. This study is the first to demonstrate that PIA and polyamorphism exist in BaF2nanomaterials and that finite grain size plays a critical role in inducing PIA and polyamorphism.

We report the high-pressure studies of RbN3by Raman and IR spectral measurements at room temperature with the pressure up to 28.5 and 30.2 GPa, respectively. All the fundamental vibrational modes were resolved by combination of experiment and calculation. Detailed spectroscopic analyses reveal two phase transitions at ∼6.5 and ∼16.0 GPa, respectively. Upon compression, the shearing distortion of the unit cell induced the displacive structural transition of phase α → γ. Further analyses of the mid-IR spectra indicate the evolution of N3–with the arrangement sequence of orthogonal → parallel → orthogonal during the phase transition of phase α → γ → δ. Additionally, the pressure-induced nonlinear/asymmetric existence of NNN and the two crystallographically nonequivalent sites of N3–were observed in phase δ.

In situ X-ray diffraction studies of rare-earth metals Sc- and Y-doped AlN nanoprisms were carried out using angle-dispersive synchrotron radiation technique in a diamond anvil cell up to approximately 40 and 35 GPa, respectively. Pressure-induced wurtzite-to-rocksalt phase transitions start at 18.6 and 16.2 GPa and complete at 29.8 and 26.5 GPa, showing lower phase-transition pressures compared with bulk AlN and AlN nanowires while slightly higher than that of AlN nanocrystals. The effects of volume expansion, volume collapse, and crystal defects on phase transition have been discussed. The distinct high-pressure behaviors can be explained in terms of the doping-induced Al vacancy defects along with substitute ions sit at the cation sites, which lead to the distortion of the crystal structure that reduce the structural stability of the doped AlN nanoprisms.

Using an in situ synchrotron angle-dispersive X-ray diffraction technique, two morphologies of nanocrystalline SrF2(i.e., nanoparticles and nanoplates) with different sizes of 11 and 21 nm were compressed up to ∼46 GPa in diamond anvil cells at room temperature. We observed that two phase transitions of the SrF2nanoparticles occur at 10.0 and 34.3 GPa, which are much higher than those in bulk SrF2. Upon decompression, the pure α-PbCl2-type metastable phase is retained when the pressure is released. In contrast, high-pressure behavior of the SrF2nanoplates is similar to that of bulk material. Such distinct high-pressure behaviors in two synthesized SrF2nanocrystals have been discussed in terms of volume expansion, exposed crystal plane, morphology, and defects. Further analysis shows that the defect effect is believed to be the major factor to affect the high-pressure behaviors in two synthesized nanocrystalline SrF2.

Recently, bacterial cellulose (BC) has become more commonly applied as a new nano-biological material within the food, paper manufacturing and pharmaceutical production industries. However, the current methods of BC production are not ideal because of their low productivity and large number of byproducts. To improve the yield of cellulose production in bacteria, various carbon and nitrogen sources for the fermentation conditions of BC by Bacillus amyloliquefaciens ZF-7 were investigated. The effects of D-glucose, yeast extract and ethanol concentration on BC production by strain ZF-7 were studied by single factor methods. Based on the above results, the effects of D-glucose, yeast extract and ethanol concentration on BC production were investigated by means of a five-level factor central composite design and response surface methodology. D-glucose and yeast extract concentration were found to have a significant linear effect on BC production, and the interaction between D-glucose concentration and yeast extract concentration also had significant influence on BC production. The obtained optimum culture medium contained 56.1 g*L[?]1 of D-glucose, 9.9 g*L[?]1 of yeast extract and 17.2 mL*L[?]1 ethanol. Under these conditions, the BC yield of B. amyloliquefaciens ZF-7 reached 7.88 g/l, which represents a 35.4% increase compared to the initial yield before the optimization.