Nanocomposite Structure Research Articles

Modeling the structure and relaxation in glycerol-silica nanocomposites.

The relationship between the dynamics and structure of amorphous thin films and nanocomposites near their glass transition is an important problem in soft-matter physics. Here, we develop a simple theoretical approach to describe the density profile and the α-relaxation time of a glycerol-silica nanocomposite (S. Cheng et al., J. Chem. Phys., 2015, 143, 194704). We begin by applying the Derjaguin approximation, where we replace the curved surface of the particle with the planar one; thus, modeling the nanocomposite is reduced to that of a confined thin film. Subsequently, by employing the molecular dynamics (MD) simulation data of Cheng et al., we approximate the density profile of a supported liquid thin film as a stationary solution of a fourth-order partial differential equation (PDE). We then construct an appropriate density functional, from which the density profile emerges through the minimization of free energy. Our final assumption is that of a consistent, temperature-independent scaled density profile, ensuring that the free volume throughout the entire nanocomposite increases with temperature in a smooth, monotonic fashion. Considering the established relationship between glycerol relaxation time and temperature, we can employ Doolittle-type analysis ("naïve" free-volume model), to calculate the relaxation time based on temperature and film thickness. We then convert the film thickness into the interparticle distance and subsequently the filler volume fraction for the nanocomposites and compare our model predictions with experimental data, resulting in a good agreement. The proposed approach can be easily extended to other nanocomposite and film systems.

Ultrawide Spectrum Metallic Plane Blackbody with Extremely High Absorption from 0.2 to 25 µm.

A plane blackbody serves as a standard radiation source, providing a precise quantitative relationship between input radiation and the output of infrared detectors, which is essential component of space infrared remote sensing instruments. However, current plane blackbodies fabricated by coating or surface structuring are unable to achieve uniform and stable high absorption in the ultrawide spectral range spanning the UV-VIS-NIR-MIR. Here, a femtosecond laser "V"- scanning method is proposed for the fabrication of cross-scale multi-layered micro- and nanocomposite structures on copper surfaces to realize ultrawide spectrum metallic plane blackbody with high absorption. The structures consist of a micrometer cone-tip structure with a depth-to-width ratio of 7:1 (period 30 µm, depth 210 µm), an oxide layer with a thickness of more than 2 µm, and nanoparticles of different sizes, achieving uniform high absorption rates exceeding 99% in the localized spectral range of 400-700 nm and over 98% from the UV to MIR range of 200 nm to 25 µm. This strategy offers a generalized approach to enhance surface light absorption, with significant application potential in infrared calibration, passive radiation cooling, and stray light suppression.

Engineering amphiphilic alkenyl lipids for self-assembly in functional hybrid nanostructures

The development of biocompatible hybrid nanosystems for advanced functional applications presents significant challenges to the research community. Key obstacles include the poor solubility of these nanosystems in water and the difficulty of precisely controlling their nanostructure dimensions and composition. A promising approach to overcoming these challenges is the self-assembly of surfactant-based building blocks into well-ordered hybrid nanostructures. In this study, we explore the relationship between structure and self-assembly in novel low molecular weight amphiphilic molecules to produce stable and biocompatible hybrid nanostructures. We investigated the self-assembly behavior of two families of amphiphiles derived from alkenyl lipids with one or two double bonds, leading to distinct hybrid supramolecular structures facilitated by the incorporation of hydrophobic iron oxide nanoparticles (IONPs) as templates. The presence of double bonds in the lipid tail and the morphology of the amphiphile influence the arrangement on the hydrophobic NPs. Amphiphiles with a single double bond in the lipid tail form highly water-soluble, well-ordered micellar-like structures on the IONP surfaces, while those with two double bonds create disordered lipid nanoparticles. Furthermore, these amphiphilic molecules can self-organize into higher-order hybrid supramolecular structures, such as vesicles, with potential applications in magnetic resonance imaging (MRI).

Microstructural and mechanical properties study of various lattice structures of SS316L-CNTs nano composites fabricated through additive manufacturing

Abstract In this work, various lattice structures, such as FCC (face-centered), BCC (body-centered), GD (Gyroid), and BGD (bare gyroid (without CNTs)) with four different porosities (60%, 70%, 80%, and 90%), were prepared through the SLM (selective laser melting) additive manufacturing process. Stainless Steel (SS) 316L alloy was utilized as the base material, while 0.2 wt.% functionalized CNTs (Carbon Nanotubes) were employed as reinforcement. The uniform dispersion of CNTs was analyzed using FESEM, TEM, and Raman spectroscopy. The results indicated that the plateau stress increases with the addition of CNTs, as well as with relative density, whereas energy absorption increases with the addition of CNTs. However, with increasing relative densities, energy absorption nature changes from increasing to decreasing. The results showed that among all lattice structures formed with CNTs addition, the Gyroid lattice exhibited the highest plateau stress, while the BCC lattice exhibited the lowest plateau stress.

Effect of Annealing Temperature on the Structural Properties and Performance of ZnO/SnO<sub>2</sub> Nanostructure of AZO-Based Humidity Sensor

Advanced research in metal oxide-based nanotechnology has led to its broad applications, which include humidity sensors as well as electronic devices. Meanwhile, zinc oxide (ZnO)/tin oxide (SnO2) composite nanostructure has established a presence in many electronic devices, and their performance can be further enhanced by electrospraying at high annealing temperatures. This paper explores how annealing temperature influences the structural properties and performance of ZnO/SnO2 nanostructures in AZO-based humidity sensors. The ZnO/SnO2 nanostructures were fabricated on AZO glass utilising electrospraying and then subjected to annealing at various temperatures: 100°C, 200°C, 300°C, 400°C as well as 500°C. The structural characteristics of the synthesized films were analysed utilising Field-Emission Scanning Electron Microscopy (FESEM) as well as X-ray Diffraction (XRD). Additionally, the humidity sensing performance of the films was evaluated based on their response time, sensitivity as well as recovery time. Following the results, a higher annealing temperature resulted in smaller crystallites and smaller diameters within the 71.6–91.9 nm range. Besides, the XRD patterns demonstrate a shift in the (002) peaks towards a higher angle value with incremental annealing temperature. In terms of the humidity sensing performance, the sensitivity level increased with increasing annealing temperature, while the recovery period and response time were reduced. In summary, the annealing temperature significantly influenced the performance of the ZnO/SnO2 composite nanostructures, which recorded the best sensitivity of 173.10, 234 seconds response time, and 80 seconds recovery time after annealing at 500°C.

Investigation of Bi2MoO6/MXene nanostructured composites for photodegradation and advanced energy storage applications

This study presents nanostructured composite Bi2MoO6/MXene heterostructure by using hydrothermal method for photodegradation of the congo-red dye and also for energy storage devices. X-ray diffractometer (XRD), High Resolution Transmission Electron Microscopy (HRTEM), Field emission scanning electron microscope (FESEM) and X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) were performed to examine the structural properties along with surface area and porosity of the material. Due to addition of MXene the larger surface area and improved pore size help to quickly break down additional organic pollutants by adsorbing them. The band gap of Bi2MoO6/MXene nanostructured composite reduced to 2.4 eV suggesting transfer of electrons from VB to CB. Bi2MoO6/MXene exhibits a high (92.3%) photocatalytic degradation rate for a duration of 16 min which was verified using UV-visible spectroscopy, also scavenger test was conducted to ascertain the reactive agent along with the degradation pathway was confirmed by LCMS. Elemental content was also established by using inductively coupled plasma mass spectrometry (ICP-MS). For estimating energy storage capacity cyclic voltammetry (CV) was performed. It was observed Bi2MoO6/MXene nanostructured composite electrodes had specific capacitance of 642.91Fg− 1, power density of 1.24 kWkg− 1, and energy density of 22.32 Whkg− 1 at a current density of 5Ag− 1 also it exhibited 64.42% capacity retention having current density 20 Ag− 1 throughout 10,000 Galvanostatic charge discharge (GCD) cycles. High electrical conductivity of Bi2MoO6/MXene electrode was again examined by Electrochemical impedance spectroscopy (EIS). These findings demonstrate the potential of Bi2MoO6/MXene nanostructured composites in both photodegradation and energy storage applications.

Adsorption performance of g-C3N4/graphene, and MIL-101(Fe)/graphene for the removal of pharmaceutical contaminants: a molecular dynamics simulation study

The rising presence of drug-related contaminants in water sources is a major environmental and public health concern. Several studies have addressed the hazardous influence of these pollutants on the lives of over 400 million people worldwide. In this study, we used molecular dynamics simulations to evaluate the efficacy of two promising composite materials for the removal of pharmaceutical contaminants by using the adsorption technique. Graphitic carbon nitride/graphene (g-C3N4/graphene) and metal-organic framework (MIL-101(Fe))/graphene have been simulated for the first time for the removal of three of the most common pollutants (acetaminophen (AC), caffeine (CAF), and sulfamethoxazole (SMZ)). The nanocomposite structure has been created and optimized using the geometry optimization task in the DFTB Modules in the Amsterdam Modeling Suite. We summarized the condition of the essential parameters (Temperature, pressure, and density) of the simulation box during the MD-simulation to ensure the accuracy of our MD-simulation results. The adsorption process, van der Waals interactions, and the adsorption capacity have been calculated by using the Reactive Forcefield (ReaxFF) software. We found that the combination of MIL-101(Fe)/graphene had a higher adsorption capacity for the removal of pharmaceutical contaminants than g-C3N4/graphene. At 40 Picosecond (Ps), 80 molecules of each pharmaceutical contaminants (AC, CAF and SMZ) have been adsorbed by MIL-101(Fe)/graphene with higher exothermic energy equated to (−1174, −1630, and − 2347) MJ/mol respectively. While for g-C3N4/graphene at 40 Ps, 70 molecules of each pharmaceutical contaminants have been adsorbed with exothermic energy equated to (−924, −966, and − 1268) MJ/mol respectively. Also, our results showed that the combination of g-C₃N₄/graphene and MIL-101(Fe)/graphene both have remarkable properties that make them effective at resisting surface clogging. Finally, the results showed that the adsorption kinetics followed a pseudo-first order model, while the adsorption isotherms for AC, CAF and SMZ adhered to Freundlich model.

Nanostructure-induced functional combination of vanishing magnetostriction and magnetic softness in ferromagnetic (GaNi)xCoCrFe (x = 0.4–1.6) high-entropy alloys

Searching for high-entropy alloys with functional properties that emerge from their multi-scale structure, we have investigated the (GaNi)xCoCrFe (x = 0.4–1.6) system. We have characterized structure, microstructure, nanostructure and chemical composition of the individual phases in the multi-phase alloys and determined their magnetic, magnetostrictive and electrical properties. We found that the alloys are ferromagnetic and exhibit functional combination of magnetic softness and vanishing magnetostriction, classifying them as energy-efficient “supersilent” materials (inaudible to a human ear) for alternating-current (AC) electromagnetic applications in the audio-frequency range. The alloys develop a two-phase structure, a face-centered cubic (fcc) and a body-centered cubic (bcc), where the fcc phase fraction decreases, while the bcc fraction increases with the increasing (GaNi)x content. Ferromagnetism of the alloys originates from the highly nanostructured bcc phase, with the ferromagnetic Curie temperatures in the range TC = 750–700 K, depending on x. The fcc phase is not nanostructured and is paramagnetic at room temperature, but undergoes a spin glass transition at Tf≈6.4 K. The magnetic softness and vanishing magnetostriction of the alloys are both nanomagnetic phenomena. The magnetic-softness and magnetostriction parameters of the x = 1.3 and 1.6 alloys make them relevant for supersilent AC applications at low frequencies.

Ternary g-C3N4/Co3O4/CeO2 nanostructured composites for electrochemical energy storage supercapacitors

Extensive use of fossil fuels causes heavy discharge of carbon dioxide, depleting energy resources and this requires environmentally friendly and effective energy storage materials. Hybrid supercapacitors (HSCs) are recently developed as effective energy storage materials enabling high capacitance retention rate and quick charging. Herein, synthesis of two-dimensional g-C3N4 nanosheets supported onto three-dimensional flower-like Co3O4/CeO2 (CoCe) ternary synergistic heterostructures are developed as effective electrodes for hybrid supercapacitor applications. Addition of g-C3N4 produces substantial surface active sites, enabling its synergistic effect with CoCe to enhance electrochemical performance having exceptional conductivity. The CoCe/g-C3N4 ternary composite electrode exhibits a higher specific capacitance of 1088.3 F g−1 at 1 A g-1 with 96 % of recycling stability over 5000 cycles, which is ∼5.5 and ∼5 folds higher specific capacitance than the pristine g-C3N4 and CoCe electrodes. EIS analysis revealed that CoCe/g-C3N4 electrode offered reduced charge transfer resistance compared to pristine electrodes. The fabricated two-electrode HSC device displays outstanding retention after 10,000 cycles with an ultra-high specific capacitance of 119.8 F g−1, excellent energy density 37.4 Wh kg−1 and power density of 749.9 W kg−1. This research showcases the perspectives of CoCe/g-C3N4 ternary electrodes in hybrid supercapacitors and other renewable energy storage devices.

A significant improvement in corrosion resistance and biocompatibility in ZrNbTiCrCu high-entropy films induced by the precipitation of Cu

Utilizing nanotechnology and composites to create a protective film on titanium alloy is an effective means of achieving the desired high performance. Self-assembly of nanocomposite structures offers a promising route to forming high entropy alloy films (HEAFs), but controlled preparation remains challenging. This work used magnetron sputtering through adjusting preparation parameters to prepare ZrNbTiCrCu HEAFs, achieving a significant improvement in corrosion resistance and biocompatibility induced by the precipitation of Cu. According to the electrochemical corrosion test, without obvious corrosion pits on the surface of S2 after corrosion, a passivation film composed of bimetallic oxide CuCrO2 formed on the film surface, indicating that ZrNbTiCrCu HEAFs have remarkable corrosion resistance performance. In the cytocompatibility experiment, the cell viability of HEAFs reached over 95 % due to the precipitation of Cu, suggesting their excellent biocompatibility. In addition, ZrNbTiCrCu HEAFs exhibit outstanding antibacterial ability, especially when the sputtering current is 0.6 A, and the in vitro antibacterial rate of the sample against Escherichia coli is close to 99 %.

Innovative xanthan gum-based nanocomposites for asphaltene precipitation prevention in shale and carbonate rocks

Asphaltene deposition in porous media creates many challenges in porous media. This study synthesizes ZnO/SiO2/xanthan nanocomposites (NCs) to adsorb asphaltene and reduce its effect on the shale and carbonate rocks. NCs structure is analyzed using SEM, EDX, BET, and FTIR tests. Also, the rocks' surface is analyzed by an atomic force microscopy (AFM) test after 48 and 96 h of contact with 20 ppm NCs and 20 mg asphaltene. Core flooding tests are performed on shale rocks using 20 ppm NCs at 5500, 4000, and 2500 psi at 48 h. Using AFM in calcite and dolomite formations and selecting core flooding tests based on that are new scenarios that followed in this paper. FTIR results confirm asphaltene adsorption on NCs's surface by changing 854 and 962 cm−1 peaks. AFM tests confirmed asphaltene adsorption on NCs surface, too. Average roughness, root mean square roughness, peak to valley roughness, and average size of the shale were higher than the carbonate sheets. At 20 ppm NCs in shale reservoirs, permeability reduction in porous media was increased up to 39.5 %, and asphaltene precipitation decreased from 8.95 and 20.06 wt% to 2.25 and 10.25 wt%, which shows our suggested scenarios were efficient.

The Elevated Temperature Tribological Performance of Tough and Superhard TaMoN-Ag films with Solute and Nanocomposite Structures

Abstract Films have been prepared with not only high hardness to guarantee excellent wear resistance but also high toughness to prevent brittle fracture at low to middle-high temperatures. On the basis of ternary transition metal nitrides with significantly improved hardness and toughness, TaMoN-Ag films with solute and nanocomposite structure were prepared by DC magnetron sputtering technology. Friction wear tests were performed between room temperature (RT) and 700 °C. When doping with trace amounts of Ag atoms (∼1.12 at.%, 4 W), TaMoN-Ag films maintain solid solution structure. TaMoN-Ag films with the Ag target power is 4 W show the highest hardness (H∼62.1 GPa), which is 58% higher than TaMoN film and 44% better than that of TaMoN films. Meanwhile, a lower wear rate (KIC∼5.87×10-7 mm3/N·m) is obtained. The tribological properties of TaMoN-Ag films at room temperatures are related to the H3/E2 and lubricious Ag phase, while the tribological properties at high temperatures are mainly due to the formation of lubricating binary metal oxides (AgxTMyOz (Magnéli phases)). The composite films generally have good resistance to plastic deformation.

Effect of the Chemical Composition and Geometry of Nanotubes on the Structure and Internal Rotation Barrier of Encapsulated Ammonia‐Boron Trifluoride: A Theoretical Investigation

AbstractThe study of the structure and conformational properties of ammonia–boron trifluoride in the cavity of 24 carbon and inorganic nanotubes using the PBE/3ζ DFT approximation showed that the conformational preference of the encapsulated molecule is determined by geometry and chemical composition of the host nanostructure. The combined effect of these factors leads to the predominance of eclipsed conformation of guest molecule for four endoclusters. In other cases, the main minimum on the potential energy surface corresponds to the staggered or pseudo‐staggered forms of BF3←NH3. The guest molecule carries the electric charge and has a shortened B←N bond. These conclusions are confirmed by the results of the virtual reaction of ammonia and boron trifluoride in the cavity of individual nanotubes.

Deposition of nanocomposite carbon-based thin films doped with copper and fluorine

This paper is focused on plasma-enhanced chemical vapor deposition (PECVD) of novel carbon-based thin films. Unique thin films were deposited from a mixture of methane, hydrogen, and a precursor containing fluorine and copper: (hfac)copperVTMS (hfac = hexafluoroacetylacetonato and VTMS = vinyltrimethylsilane). Using the (hfac)copperVTMS precursor in PECVD deposition results in the advantageous chemical composition of carbon-based thin films while maintaining sufficient mechanical properties. Furthermore, with optimized plasma parameters, the films deposited on the substrate exhibit a nanocomposite structure. This nanostructured surface can increase the surface area, which is beneficial for various applications, including antibacterial and antiviral properties. The radiofrequency glow discharge at low pressure (≈70Pa) and power P=25W and P=250W was used for deposition. Deposited thin films were analyzed using X-ray photoelectron spectroscopy, water contact angle measurement, atomic force microscopy, and nanoindentation techniques. Despite the doping of carbon-based thin films with soft copper, the prepared films exhibited sufficient mechanical properties, which are crucial for the future implementation of this deposition process.

Novel approaches to improving gas separation: Ionic liquids coated coke/ NH2-UiO-66-based mixed matrix membranes for CO2/N2 separation

Permeability and separation efficiency of mixed matrix membranes (MMMs) are two important aspects. Polymeric membranes offer excellent mechanical and physical properties; however, they have a low permeability. To enhance the permeability and separation performance of polyvinyl chloride (PVC) membranes, Cholinium amino acid-based (IL) were impregnated with activated coke/ NH2-UiO-66 (Zr) (AC/MOF) composite and then IL@AC/MOF filler was incorporated into PVC matrix. FTIR spectroscopy, TGA, SEM, EDX, and Brunauer-Emmett-Teller (BET) surface area measurement were used to characterize the MMMs prepared. The porous structure of MMMs nanocomposites causes AC/MOF composite to effectively accelerate gas the diffusion in the PVC matrix. The permeability measurements for CO2 and N2 were made at 288.15, 298.15, 308.15, and 318.15 K at pressure 3 bar The outcomes indicates that the incorporation of the IL@AC/MOF filler increased the permeability of the PVC/AC/MOF MMMs compared to the pure polymeric membrane. The mixed matrix membranes exhibit superior gas separation performance, surpassing the 2008 Robson's Upper Bound.

ZnS-zeolitic imidazolate framework nanostructure anchored on Ni nanowires as a bifunctional electrocatalyst for high-efficiency overall water splitting

The design and construction of stable and inexpensive bifunctional catalysts for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) present a challenge in electrocatalytic water splitting. In this study, we utilized zeolitic imidazolate frameworks-8 (ZIF-8) as the precursor to fabricate ZnS-ZIF-8 via facile sulfidation processes. The ZnS-ZIF-8 nanostructures were anchored on the surface of the nickel nanowire (denoted as Ni NWs@ ZnS-ZIF-8 nanocomposite) and their catalytic activity for HER, OER, and overall water splitting were studied. The prepared Ni NWs@ ZnS-ZIF-8 revealed a low overpotentials value of 90 and 260 mV at 10 mA cm−2 for HER and OER in 1.0 M KOH solution, respectively. The alkaline electrolyzer assembled by Ni NWs@ ZnS-ZIF-8 provides a low cell voltage of 1.61 V at 10 mA cm−2 current density to boost the overall water splitting and robust stability for 15 h. The superior electrocatalytic activity of Ni NWs@ ZnS-ZIF-8 is owing to the facile and effective electron transport of Ni NWs, accessible active sites of ZnS-ZIF-8, and as well as the synergistic effect of the nanocomposite structures. This finding presents a viable methodology for synthesizing a proficient noble-metal-free catalyst for energy conversion and storage.

Comprehensive study of CeO2/CuFe2O4 nanocomposites: Structural, EPR, magnetic, electrochemical, and cytotoxicity properties

This study dives into the successful synthesis of CeO2/CuFe2O4 nanocomposites using the auto-combustion approach and elucidates their characteristics. The electrochemical analysis of samples calcination produced at 700 °C (CeO2/CuFe2O4) revealed good results, with a specific capacitance (Cs) of 123 F/g at a current density (CD) of 0.25 A g−1 in a 1 M KOH solution. Significantly, these findings emphasize the established technique's potential for producing new, highly active, flexible, and environmentally friendly substrate materials appropriate for a variety of applications in supercapacitors. CeO2/CuFe2O4 nanocomposites may be useful in biological and medicinal research. Despite their extensive use, little study has been conducted to investigate their possible impact on cell viability, in normal cell lines. The positive benefits of the CeO2/CuFe2O4 nanocomposite structure were assessed using X-ray diffraction (XRD). To assess the impact of these nanocomposites, MTT cytotoxicity tests were performed on normal (mouse muscle fibroblast - BLO-11) cell lines. The results show that CeO2/CuFe2O4 nanocomposites have a high potential for biomedical applications, as they had no harmful effects on the cell types evaluated. As a result, the structure of the material appears to be crucial in determining both electrochemical performance and cell longevity. This discovery is significant because it provides useful insights into the morphological engineering of electrodes for a variety of applications and influences future material development.

Multi-synergy enabling Ni-doped MoS2@N-doped carbon composite as versatile catalysts toward hydrogen production and photovoltaics

Construction of efficient non-precious catalyst with desired chemical composition and well-defined nanostructure is of great essential to enhance the kinetics of hydrogen evolution reaction (HER) and triiodide (I3−) reduction reaction (IRR), which is conducive to promote the development of green hydrogen production and obtain impressive photovoltaic performance of dye-sensitized solar cells (DSSCs). Herein, ZIF-8 derived N-doped carbon (NC) wrapped with two-dimensional Ni-doped MoS2 nanosheets (Ni–MoS2@NC) are elaborately designed. The catalytic activity of Ni–MoS2@NC for HER and IRR are significantly improved by modifying electronic structure through heteroatom doping. The optimized Ni–MoS2@NC has lower overpotential of 122 mV at 10 mA cm−2 in comparison with counterpart. Meanwhile, the power conversion efficiency (PCE) of DSSCs based on Ni–MoS2@NC CE catalyst is comparable to that of Pt. Density functional theory (DFT) calculation is used to unveil the mechanism of Ni–MoS2@NC for alkaline HER and IRR, namely, the multi-synergy of various sites endows Ni–MoS2@NC with appropriate Gibbs free energy for H∗ adsorption and water dissociation energy, while the top and interfacial S sites of Ni–MoS2@NC are responsible for the adsorption and activation of I3−. Our work provides a feasible route to design efficient catalysts in the field of energy conversion and understand mechanism.

Aerobic bacteria induced biomineralization: effects of nutrient and calcium content on the nanostructure and chemical composition of simulated cement mixture

During the past two decades, aerobic bacteria induced biomineralization has gained popularity for autonomous sealing of cracks in concrete structures due to its environmentally friendly characteristics of carbon retention. However, the mechanism of the biomineralization induced by aerobic bacteria for concrete crack sealing is still unclear due to the complex chemistry of cement matrix. Also, as the main nutrient for bacterial growth, the effect of yeast extract (YE) on biomineralization should be properly evaluated. For the first time, this study investigates the effects of YE and calcium content on the development of nanostructure and chemical composition of cement matrix during the biomineralization process induced by aerobic bacteria Bacillus cohnii. The effects of calcium content were realized by constructing a simulated cement mixture consisting of calcium hydroxide and synthesised C-S-H with different C/S ratios. The effects of YE content were evaluated by the addition of different amounts of YE into simulated cement mixture with different C/S ratios. Results suggest that 10g/l of YE can cause a high pH value of 10 and an unsuccessful growth of bacteria in simulated cement mixture with C/S ratios 0.6 and 0.8. Upon increasing the YE from 10 g/l to 20 g/l, the pH reduced from 10 to 9 and the bacteria was successfully grown. Higher amounts of bicarbonate ions can cause an enhanced decalcification of synthesised C-S-H rather than calcium hydroxide. The aerobic bacteria Bacillus cohnii showed superior performance on calcium absorption and calcite precipitation, being a promising way for practical concrete crack sealing.

Stable random laser of perovskite quantum dots based on SiO2-QDs-SiO2 composite nanostructure

In recent years, metal halide perovskite has gradually become a hotspot in the field of optoelectronics. However, the inherent instability of CsPbX3 quantum dots (QDs) seriously affects the amplified spontaneous emission (ASE) or lasing performance. Herein, the highly stable CsPbBr3 random laser is realized in SiO2-QDs-SiO2 (SQS) composite nanostructure doped with Ag nanoislands. The strong scattering generated by SQS composite nanostructure and the localized surface plasmon resonance (LSPR) of metal silver nanoislands provide optical feedback for the formation of random laser. Then a coherent random laser with low threshold (∼2.2 mJ/cm2) is obtained. SiO2 microspheres anchor QDs to avoid photoinduced regeneration and fluorescence quenching caused by QDs clusters. The inner QDs of SQS are effectively protected from water erosion, thus resulting that the samples have higher water resistance. The luminescence intensity still maintains 70 % of the original intensity after 40 days with the addition of pure water. Our research provides an effective method for improving the water stability of perovskite QDs. The highly stable random laser based on perovskite quantum dot film has a wide application prospect in integrated optoelectronics, display imaging and sensing measurement.