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SnO2 films as a promising electron transport layer (ETL) have been widely used in planar-type perovskite solar cells to achieve an impressive improvement in the conversion efficiency. However, compared with a mesoporous ETL, the interfacial charge carrier transfer of the SnO2 ETL is severely limited due to the issues of oxygen vacancy defects and crystal lattice mismatch between SnO2 and the perovskite, which generally leads to the growth of randomly stacked and porous perovskite layers and subsequently impacts the charge transport and transfer properties. In this work, we developed a facile approach by inducing a bifunctional molecule, β-alanine, into the SnO2 ETL, which can serve as a bridge to modulate the interfacial charge transfer and the perovskite crystallization kinetics. Benefited by the interfacial β-alanine, we grew a highly orientational perovskite layer that exhibited superior charge transport properties. Meanwhile, the β-alanine caused an intimate connection between the perovskite and SnO2 to enhance the interfacial charge transfer. As a result, the power conversion efficiency (PCE) of the β-alanine-modified device achieved a much-improved value of 19.67% and showed high reproducibility. This work provides a way for developing a high-performance ETL toward the scalable fabrication of highly efficient PSCs.

In this work, novel antibacterial cellulose diacetate/poly(ethylenimine)/hyaluronic acid (CDA/PEI/HA) composite three-dimension (3D) scaffolds were prepared through electrospinning and post-processing. Firstly, CDA/PEI 2D composite nanofiber membranes were prepared by electrospinning, and then the CDA/PEI/HA 3D composite scaffolds were fabricated by post-processing and freeze-drying of CDA/PEI membranes. In particular, HA was added to improve the biocompatibility of composite scaffolds. Compared with CDA/PEI scaffolds, CDA/PEI/HA composite scaffolds showed higher water absorbing rate, higher water retention rate and higher mechanical strength. Moreover, CDA/PEI/HA composite scaffolds with abundant positive charge were benefit for improving antibacterial activity. CDA/PEI/HA scaffolds with biology function of HA were benefit for improving hemocompatibility and cell proliferation of CDA/PEI scaffolds. In summary, antibacterial CDA/PEI/HA scaffolds could protect wound from bacterial infection, improve cellular behavior and accelerate wound healing. Thus, CDA/PEI/HA scaffolds could be potential application for wound dressing.

Temperature-responsive resistance transition behaviors of the melamine sponges wrapped with different graphene oxide derivatives (i.e. nanoribbon, wide-ribbon and sheet) were investigated. Melamine sponge composites coated by three types of GO derivatives were prepared by a simple dip-coating approach. All these composites show good mechanical flexibility and reliability (almost unchanged compressive stress at 70 % strain after 100 cycles), high hydrophobicity (water contact angle >120°), excellent flame resistance (self-extinguishing) and structural stability even after burning, which was used to construct the resistance-based fire alarm/warning sensor. Notably, the different resistance response behaviors of such sensors are strongly dependent on the GO size and network formed on the MF skeleton surface. Typically, at a fixed high temperature of ∼350 ℃, the three fire alarm sensors show different response time (to trigger the alarm light) of 6.3, 8.4 and 11.1 s for nanoribbon, wide-ribbon and sheet at the same concentration, respectively. The structural observation and chemical analysis demonstrated that the discrepancy of temperature-responsive resistance transition behaviors of various GO derivatives was strongly determined by their different thermal reduction degrees during the high-temperature or flame treating process. This work offers a design and development for construction of smart fire alarm device for potential fire prevention and safety applications.

Carbon nitride (CN) polymer is considered as a potential material for photocatalysis, but surfers from the low photoconversion efficiency due to its high defect density. Although the defects can be limited through the crystallization of CN, the photocatalytic activity of single-component photocatalyst is still restricted by the recombination of photoexcited carriers. In our work, the ordered Schottky heterojunction of heptazine-based crystalline carbon nitride (HCN) and Ti3C2 MXene was successfully prepared through ionothermal method. The HCN/Ti3C2 composites exhibit higher photocatalytic performance than pristine HCN. Particularly, the HCNT20 sample exhibits the highest photocatalytic H2 evolution activity, which is about 8 and 2 times higher than that of bulk CN and pristine HCN, respectively. The results of charge transfer dynamics and DFT calculation reveal that the photocatalytic enhancement mechanism is primarily attributed to the synergistic effects of crystallization of CN, excellent conductivity of Ti3C2 and well-constructed Schottky heterojunction.

Yttrium borides have attracted much attention for their superconducting and high chemical stability. However, the fundamental knowledge of the mechanical properties and hardness of yttrium borides is rather lack. Here, we performed a systematic investigation on yttrium borides with various stoichiometries based on an unbiased CALYPSO structure search method and first-principles calculations. A new YB6 compound with R3m hexagonal structure is observed, which is more stable than the experimental synthesized Pm3m phase. The calculated formation enthalpy, elastic constants, and phonon dispersions distinctly show that the R3m-YB6 is energetically, mechanically, and dynamically stable. The density of states and electronic band structure reveal that all the stable yttrium borides are metallic. Based on a semiempirical method, the Vicker hardness of R3m-YB6 is expectant to be 37.0 GPa, indicating it is a potential ultrahard metal. Our results provide insights for future synthesis and design of new type functional materials.

A series of triphenylamine (TPA) derivatives with various substituent groups were prepared and showed different absorption and fluorescence characteristics due to the substituent effect. On account of the existence of pyridine units, these TPA derivatives exhibited acid-induced tunable multicolor fluorescence emission including white light emission. In addition, acid-induced fluorescence regulation of these compounds has been also realized in the solid state, which enable them to be successfully constructed the stimuli-responsive fluorescent films and fluorescent inks for inkjet printing.

Hydrogel-based wearable devices have attracted tremendous interest due to their potential applications in electronic skins, soft robotics, and sensors. However, it is still a challenge for hydrogel-based wearable devices to be integrated with high conductivity, a self-healing ability, remoldability, self-adhesiveness, good mechanical strength and high stretchability, good biocompatibility, and stimulus-responsiveness. Herein, multifunctional conductive composite hydrogels were fabricated by a simple one-pot method based on poly(vinyl alcohol) (PVA), sodium alginate (SA), and tannic acid (TA) using borax as a cross-linker. The composite hydrogel network was built by borate ester bonds and hydrogen bonds. The obtained hydrogel exhibited pH- and sugar-responsiveness, high stretchability (780% strain), and fast self-healing performance with healing efficiency (HE) as high as 93.56% without any external stimulus. Additionally, the hydrogel displayed considerable conductive behavior and stable changes of resistance with high sensitivity (gauge factor (GF) = 15.98 at a strain of 780%). The hydrogel was further applied as a strain sensor for monitoring large and tiny human motions with durable stability. Significantly, the healed hydrogel also showed good sensing behavior. This work broadens the avenue for the design and preparation of biocompatible polymer-based hydrogels to promote the application of hydrogel sensors with comfortable wearing feel and high sensitivity.

The design and synthesis of low-cost and efficient bifunctional electrocatalysts for water splitting are critical and challenging. Hereby, a bimetallic phosphide embedded in a N and P co-doped porous carbon (FeCoP2@NPPC) material was synthesized by using sustainable biomass-derived N- and P-containing carbohydrates and non-noble metal salts as precursors. The obtained material exhibits good catalytic activities in hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and overall water splitting. The bimetallic alloy phosphide (FeCoP2) is the active site for electrocatalysis. Theoretical calculation indicates that the sub-layer Fe atoms and top-layer Co atoms in FeCoP2 exhibit a synergistic effect for enhanced electrocatalytic performance. The carbon matrix around the FeCoP2 can prevent the corrosion during the catalytic reactions. The hierarchically porous structure of the FeCoP2@NPPC material can promote the transfer of electrons and electrolyte, and increase the contact area of the active sites and electrolytes. N- and P-containing functionalities improve the wetting and conductivity properties of the porous carbon. Due to the synergistic effects, FeCoP2@NPPC requires a low overpotential of 114 and 150 mV at the current density of 10 mA cm-2 for HER in 0.5 M H2SO4 and 1.0 M KOH, and an overpotential of 236 mV for OER in 1.0 M KOH solution, which are much lower than those of FeP@NPPC and CoP@NPPC. Based on the density functional theory calculation, FeCoP2 yields the smallest Gibbs free energy change of rate-determining step among the samples, which leads to better electrochemical performances. In addition, when FeCoP2@NPPC was used as a bifunctional catalyst in water splitting, the electrolyzer needed a low voltage of 1.60 V to deliver the current density of 10 mA cm-2. Furthermore, this work provides a strategy for preparing sustainable, stable, and highly active electrocatalysts for water splitting.

The development of novel luminescent materials with multi-stimuli responsive and multi-functional properties is required. In this work, we designed and synthesized a novel AIE-based fluorenone derivative, MBPF. The donor–acceptor–donor (D–A–D) structure promoted the intermolecular hydrogen bonding capacity of the exposed oxygen atom in fluorenone. MBPF displayed three different aggregation morphologies: an amorphous floccule Y-MBPF with yellow-green luminescence, a block crystal O-MBPF with orange luminescence, and a needlelike crystal R-MBPF with red emission. They all exhibited reversible stimuli-response phase transitions to temperature and shear, accompanied by fluorescence switching. The orange crystal O-MBPF was also sensitive to isotropic hydrostatic pressure with prominent and contrasting luminescent conversion. Furthermore, we prepared MBPF nanocrystallites and encapsulated them with DSPE–PEG and the monoclonal antibody cetuximab (C225) to obtain MBPF-C225 NPs, which were biocompatible and photostable. They could be used for specific cancer cell imaging through receptor-mediated endocytosis.

Occurrence and flow of hydrocarbons in nanopores are two important issues in the effective exploitation of shale oil reservoirs. In this study, molecular dynamics simulations are employed to investigate the mechanisms about occurrence and flow of octane in slit-shaped quartz nanopores. We show that the occurrence state of octane and, therefore, its flow behavior are profoundly affected by the potential field from quartz walls and adsorption layers if the nanopore width w becomes less than 50 Å. Two main adsorption layers are always formed, adjacent to the walls and independent of w, due to two potential wells generated by the attractive potentials of the walls. Each pair of symmetrical adsorption layers, each of which can be considered as a solid-like surface, forms a confined environment similar to a nano-slit. The attractive potentials from them are found to be the cause for the formation of the adsorption layers between them. The obvious bulk phase of octane is formed in the pore of w = 50 Å due to the wide zero potential barrier induced by the innermost two adsorption layers. The nonlinear dependence of flow rate on pressure gradient shows that Darcy's law fails to describe the flow in the nanopore. The non-Darcy behavior mainly arises from adsorption effects from the walls and the adsorption layers, slippage between octane and walls and between adjacent two adsorption layers, and the molecular exchange between adsorption layers. A modified microscopic model is established to predict the dependence of flow rate on potential field, pressure gradient and w, which is in a good agreement with our simulation results and verified by the dodecane flow through the nanopore. Our work can be of great importance for revealing the mechanisms of occurrence and transport and guiding the estimation and exploitation of shale oil resources.

Zirconia ceramics and carbon-based materials are widely adopted in medical and dental applications due to their excellent biocompatibility and aesthetics. However, fracture toughness of ceramic materials limits their application in clinical dentistry because of the existence of residual stress. In this study, zirconia/graphene oxide (ZrO2-GO) composite ceramics were fabricated by hot-press sintering. Residual stresses developed on the surface of ZrO2-GO composite ceramics were evaluated by X-ray residual stress analysis and indentation techniques. The variation of surface residual stress with GO content was evaluated, and found to be consistent with that of fracture toughness. The generation of residual stress was found to be directly related to fracture toughness. Residual stress calculated by theoretical formula of indentation method was consistent with that measured by X-ray diffraction in line with the content of GO. Based on above results, it is concluded that 0.1–0.15 wt% GO composite ceramics possessed better mechanical properties.

The correlation between aggregates and bound rubber structures in silicone rubbers (S(phr)) with various silica fractions (ΦSi) has been investigated by contrast matching small-angle neutron scattering (SANS), swelling kinetics, and low-field nuclear magnetic resonance (NMR). Mixed solvents with deuterated cyclohexane fractions of 4.9% and 53.7% were chosen to match the scattering length densities of the matrix (SMP(phr)) and the filler (SMS(phr)), respectively. All the data consistently suggest that: (i) There is a critical threshold ΦSic between 10 and 30 phr; below Φsic, the isolated aggregates are dominant, while beyond Φsic, some rubber fraction is trapped among the agglomerate; (ii) Φsr-independent thicknesses around 7.5 nm (NMR) and 8.6 nm (SANS) suggest that the bound rubber formation is determined by inherent properties of the components, and the power-law around 4.2 suggests an exponential changed gradient density of the bound rubber; (iii) SMS(80) presents a bicontinuous bound rubber with three characteristic lengths of 41, 100, and 234 nm. The expanded correlation length, a 20 nm smaller aggregate sizes suggest that such existent bicontinuous network in dry samples with less ΦSi is kind of impacted by swelling. With the obtained bound rubber models, the reinforcing mechanism of filled silicone rubber is elucidated.

Carbon dots (CDs) have received increasing attention as fluorescence sensors for the detection of different metal ions and organic small molecules. In this work, κ-carrageenan (κ-Carr)-derived carbon dots (C-CDs) were synthesized via a facile hydrothermal treatment with κ-Carr as a carbon source. The produced C-CDs exhibited a high fluorescence with fluorescent quantum yield up to 20.6% and excellent fluorescent stability under diverse conditions (UV radiation, pH value and ionic strength). Then, the C-CDs were utilized as dual functional sensing probe to detect both Fe3+ and oxytetracycline (Otc). The fluorescence intensity of C-CDs was selectively quenched by Fe3+, in sharp contrast to dozens of other metal ions like Al3+, Ba2+, Ca2+, Co2+, Mg2+, Pb2+, Na+, Hg2+, Ni2+, Zn2+, Cd2+ and Cu2+. Coincidentally, this fluorescence could also be selectively quenched by Otc, entirely distinct from related physiological molecules like glycine, ammonium hydroxide, glucose, urea. The prepared C-CDs could be used for label-free sensitive and selective fluorescent detector for Fe3+ in a wide concentration range of 0–500 μM with a detection limit of 0.21 μM and for Otc as well in the range of 0–100 µM with a detection limit of 0.05 µM. Moreover, the fluorescent C-CDs were successfully used for Fe3+ and Otc detection in some real samples, suggesting great application potential in fluorescence sensing of trace metal elements and antibiotics.

In this study, a composite aerogel (WP-MMT) composed of wastepaper (WP) and montmorillonite (MMT) was prepared by ambient pressure drying technology to adsorb Cd2+. The study of compression performance indicated that the composite aerogel had ideal mechanical strength when the mass ratio of WP to MMT was 1:1. The specific surface areas of the aerogels modified by hydrogen peroxide (WP-MMT-H2O2) and sodium hydroxide (WP-MMT-NaOH) were increased greatly. The sorption isotherms and kinetics of Cd2+ sorption on WP-MMT-H2O2 and WP-MMT-NaOH were investigated. The Cd2+ sorption data could be well described by a simple Langmuir model, and the pseudo-second-order kinetic model best fitted the kinetic data. The maximum sorption capacity obtained from the Langmuir model was 232.50 mg/g for WP-MMT-NaOH. The adsorption mechanism of WP-MMT was chemical adsorption of a single-molecule layer. In general, it was proved that the composite aerogel with high adsorption capacity of Cd2+ could be synthesized from modified WP and MMT by ambient pressure drying. The composite aerogel fabricated by wastepaper and montmorillonite showed bright application prospect in the aqueous heavy metal pollution control.

An ultrafine tin dioxide/N, P-doped porous carbon (SnO2/NPPC) nanocomposite is prepared through in-situ growth of tin dioxide (SnO2) nanoparticles in N, P-doped porous carbon (NPPC). Owing to the in-situ growth method, the size of SnO2 nanoparticles in SnO2/NPPC is quite small and uniform (generally less than 5.0 nm). NPPC provides a support and a conductive carbon skeleton for the SnO2 nanoparticles. The small SnO2 nanoparticles are less likely to aggregate during the discharge–charge process due to the presence of Sn–O–C bonding and nanoconfinement effect of SnO2 nanoparticles in carbon matrix. The N and P doping can provide abundant defects to facilitate the penetration of Li+ or Na+ into the interior of the electrode. In addition, the presence of Sn–N bonding can further improve the electrochemical properties of the electrodes. Thus, as an anode material for lithium-ion batteries, SnO2/NPPC possesses an enhanced rate performance, an excellent cycling stability, and a high initial Coulombic efficiency. The structure of the ultrafine SnO2 nanoparticles is well maintained in cycled SnO2/NPPC. Meanwhile, SnO2/NPPC also possesses good electrochemical performance as an anode for sodium-ion batteries. The good electrochemical properties for SnO2/NPPC materials can be ascribed to the synergetic effect between small SnO2 nanoparticles and NPPC.

In this work, hyperbranched polyurethane elastomer (HBPUE) electrolyte and aluminum foil (Al) were joined together by anodic bonding. It provides a possibility for packaging of flexible devices to use anodic bonding. The HBPUEs were designed and prepared via prepolymerization method cured at room temperature using polypropylene glycol (PPG), toluene-2,4-diisocyanate(TDI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and the varying ratios of trimethylolpropane (TMP)/1,4-butanediol (BDO). All HBPUEs prepared exhibited low glass transition temperature (Tg) and good thermal stability. The highly branched structures increase the proportion of amorphous phase of HBPUEs, resulting in a high ionic conductivity with a highest value of 2.38 × 10−4 S cm−1 at 70 °C when adding TMP and BDO at the ratio of 0.45:0.45 (HBPUE3). There are no obvious diffraction peaks of the LiTFSI in the XRD patterns, indicating that LiTFSI was dissolved in polyurethane matrix completely. XRD results show that the structures of PEO-PUEs are amorphous. The HBPUEs prepared have good mechanical properties that can be used as packaging material. After bonded, the microstructures of the bonded interface between HBPUE and Al with a clear intermediate bonding layer could be observed by the cross-sectional scanning electron microscopy (SEM) images, and the elements diffused were also detected by the energy-dispersive spectrometer (EDS), indicating that the HBPUEs and Al were bonded together successfully. The maximum tensile strength for HBPUE3/Al was up to 1.15 MPa. All results demonstrated that the HBPUEs prepared would be a promising packaging material for flexible devices applied to anodic bonding.

Polyethylene oxide (PEO) and poly(propylene oxide) (PPO), especially their tri-block copolymers PEO-PPO-PEO (poloxamers), have a broad range of applications in biotechnology and medical science. Understanding their specific interactions with biomembranes is the key to unveil the unique features of poloxamers either as membrane-healing or membrane pore-forming agents. Based on the coarse-graining convention of the MARTINI force field and the big multipole water (BMW) model, which has a three charged site topology and can reproduce the correct dipole moment of four-water clusters, we generated coarse-grained (CG) models with analytical and numerical potentials for PEO and PPO homopolymers and poloxamers in dilute solution. The effective bonded interaction potentials between CG beads were determined from the probability distributions of bond lengths, angles and dihedrals that are determined from atomistic simulations. The nonbonded interaction parameters were fine-tuned to reproduce the conformational properties of atomistic PEO and PPO homopolymers and poloxamers via extensive CG simulations of PEO and PPO homopolymers and poloxamers in a BMW water environment. The reported CG models provide a promising framework for a comprehensive understanding of the microstructural, conformational, and dynamic properties of poloxamers and their delicate interactions with other species in an explicit water environment.

Carrier recombination and charge loss at the interfaces of perovskite layers have a significant influence on high-performance planar perovskite solar cells (PSCs). We employed two-dimensional graphitic carbon nitride (g-C3N4), which is a heat-resistant n-type semiconductor, to modify the electron-transport layer/perovskite and perovskite/hole-transport layer interfaces, respectively. g-C3N4 could passivate the surface trap states of the methylammonium lead iodide light absorber through the formation of a Lewis adduct between N and the under-coordinated Pb, and it could also remarkably reduce the grain boundaries between perovskite crystal particles. A maximum power conversion efficiency (PCE) of 19.67% (Voc = 1.14 V, Jsc = 21.45 mA cm−2, FF = 0.807) could be obtained from planar PSCs with long-term stability using dual-positioned g-C3N4. Therefore, we consider that ultrathin semiconductor films with a Lewis base nature are suitable as dual-functional transport materials for devices. This work provides new guidance for dual-interfacial modification to improve the PCE and stability of devices.

Despite being promising photovoltaic materials, widespread use of organic–inorganic halide perovskite materials is still hindered by their undesirable stability. To cope with this challenge, methylamine (MA) is doped into triple cation perovskite single crystals of (FA0.95−xMAxCs0.05)PbI3, and cesium-containing triple cation perovskite single crystals with five different MA molar ratios (x = 0, 0.05, 0.10, 0.15, and 0.20) are synthesized and characterized. Among them, (FA0.8MA0.15Cs0.05)PbI3 shows high stability against water-oxygen and light for 60 days, and the thermal decomposition temperature of (FA0.8MA0.15Cs0.05)PbI3 reaches as high as 305 °C. Besides, the carrier lifetime of (FA0.8MA0.15Cs0.05)PbI3 is up to 5.957 μs, which remains as 5.646 μs (95%) after 60 days of light illumination. This work studies the stability of perovskite single crystals based on (FA0.95−xMAxCs0.05)PbI3 compositions and provides a reference for the discovery of novel perovskite photovoltaic devices with high efficiency and long-term stability.

Carbazole-based porous organic polymers (CPOPs) and their derived carbon materials have been found to be promising candidates for many applications, such as gas adsorption and energy storage, due to their highly porous structure and nitrogen-containing functionalities. However, most of the reported CPOPs or CPOP-derived carbons are powder-like materials, which limit their industrial applications. Hereby, flexible nitrogen-doped porous carbon materials (FNPCs) were synthesized through in situ oxidative coupling polymerization in/on flexible biomass textiles and subsequent carbonization procedures. During the carbonization procedure, the microporous structure and the nitrogen in CPOPs were maintained. The CPOP-derived FNPCs possess good flexibility and relatively large specific surface area and pore volume, together with high nitrogen contents. In light of these merits, gas adsorption, separation, and preliminary sensing experiments were conducted. The carbon dioxide and methane adsorption capacities of the FNPC are 21.0 wt% and 3.5 wt% (at 273 K and 1.0 bar), respectively. Meanwhile, due to the interaction between CO2 and the FNPCs, the materials can also be used for CO2/N2 separation and gas sensing, and a preliminary experiment on FNPC as a gas sensor for exhaled breath was conducted. More importantly, the materials are flexible and they can be easily assembled into gas adsorption devices and sensors.

We demonstrate the first electrically-pumped, GaAs-based vertical-cavity surface-emitting lasers (VCSELs) emitting in the 1500 nm range that operate in continuous wave mode at and above room temperature. The VCSELs employ a dilute-nitride GaInNAsSb/GaNAs multiple quantum well active region, two n-doped AlGaAs/GaAs distributed Bragg reflectors and a GaAs tunnel junction. Continuous-wave single-mode lasing was observed up to 50 °C with room-temperature threshold current densities below 3 kA/cm2. Small signal measurements indicate that dilute nitride GaInNAsSb/GaNAs active regions are capable of high speed modulation.

Funding Information: This work is supported by the National Natural Science Foundation of China under grant no. 6207030573 , the National Basic Research Program of China (973 Program) under grant no. 2012CB934200 , and the Specialized Research Fund for the Doctoral Program of Higher Education under grant no. 20130071110018 . Publisher Copyright: © 2021 Elsevier B.V. Copyright: Copyright 2021 Elsevier B.V., All rights reserved. The NO2 sensing performance of a special lateral photovoltaic self-powered gas sensor based on the N-hyperdoped microstructured silicon (N-Si) is systematically studied under the different light illumination. The dependence of sensing characteristics on light intensity and wavelength is obtained, respectively. Results show that the sensing properties can be changed effectively by the different intensities and wavelengths, suggesting that a multidimensional regulation/optimization for the sensing characteristics is possible by light. More interestingly, the light with wavelength of 940 nm and intensity of ∼18 μW/cm2 could bring a comprehensive optimization for gas sensing, under which the N-Si sensor exhibits the excellent overall performance with simultaneously the low light power needed, good gas response, high sensitivity, wide detectable range and short response time at room temperature.

A sensor used to monitor tissue deformation requires good flexibility, stretchability, self-adhesion, cyto-compatibility, and antibacterial property. Here, we prepared hydrogel sensor based on O-carboxymethyl chitosan (O-CMCS) and poly(vinyl alcohol) (PVA) for monitoring human and organ motions. Based on the host-guest complexing of poly(β-cyclodextrin) with diamantane, a cross-linker containing multiple aldehyde groups was prepared for cross-linking with O-CMCS through Schiff base linkages. Borax was used as the second cross-linker to cross-link PVA through dynamic borate ester bonds. Carbon nanotubes (CNTs) were added into the hydrogels to improve their electrical conductivity and mechanical properties. The obtained hydrogel exhibited rapid self-healing ability with healing efficiency as high as 97%–103% (in 15 s), good adhesion to human skin and wet organ, good antibacterial property, cyto-compatibility, and stretchability. Furthermore, the hydrogel sensor can monitor the respiratory movement of porcine lungs and the beating of rat hearts.

Flame-retardant silane-grafted-graphene oxide (silane-GO) papers are fabricated via a green and versatile silane-assisted assembling strategy, and their use as early fire alarm sensors are investigated. Different silane molecules with alkoxy groups can react with GO in aqueous solution via hydrolysis and condensation reactions and thus assemble into the aligned silane-GO papers. The silane-GO papers exhibit good mechanical flexibility, strong acidic/alkaline tolerance, excellent flame resistance and improved thermal stability at low silane content in comparison with pure GO paper. Structure observation and analysis disclose that a compact nano-silica protective layer transformed from the grafted silane molecules during combustion is formed to inhibit the thermal degradation of GO sheet effectively. Furthermore, the insulating silane-GO paper can be thermally reduced into the conductive reduced GO network after encountering high-temperature or flame situation, thus providing ideal early fire alarm response, i.e. rapid flame detecting response time of ∼1.6 s and fire early warning response of ∼5 s when attach on the heat resistor. These results suggest that the silane-GO papers are promising for development of advanced materials as smart sensors in early fire alarm applications.

The molecular dynamics simulations in this work were aimed to provide a molecular insight into chain structure effects on non-isothermal crystallisation of polyethylene (PE) chains. The crystallisa...

Three-dimensional (3D) vapor grown carbon nanofiber (VGCF)/clay/silicon rubber (SR) (VCS) coated polyurethane (PU) foam composites were fabricated by a facile dip-coating method. The insulating clay sheets were used as second-phase fillers to tailor the conductive VGCF network in the 3D porous conductive composites. The optimized VCS-coated PU (VCS@PU) foam composites exhibited excellent mechanical elasticity and durability, outstanding acid and alkali resistance, and stable electrical conductivity. Interestingly, vapor response time of the VCS@PU foam composites was strongly dependent the clay content, e.g., from 250 to 15 s for 0 and 1.2 wt% clay, respectively. Furthermore, the VCS@PU foam composites showed good reproducibility and high responsivity (˜106 resistance change) for a series of solvents (e.g., n-hexane, carbon tetrachloride, and chloroform); and a low detection limit of 1 ppm for n-hexane vapor was achieved. The related mechanisms of highly efficient vapor sensing behaviors were proposed and discussed, and the clay sheets acted as insulating sites among the bridged VGCFs network, inducing rapid destruction of the conductive network when the SR swelled. This work paves a new way for design and development of advanced highly sensitive and fast responsive organic vapor sensors by using an insulating second filler to tune porous conductive structure.

The development of three-dimensional (3D) graphene nanoribbon (GNR) based porous composites with both mechanical reliability and multiple functionality has attracted great interest due to their promising applications in strain sensing, oil/water separation, etc. Herein, we report a facile strategy to fabricate robust porous 3D GNR wrapped polymer foam composites through modulating an interconnected GNR network and introducing a flexible polydimethylsiloxane (PDMS) coating. By simply adjusting the graphene oxide nanoribbon (GONR) concentration in aqueous solution followed by chemical reduction, the presence of the reduced GONR (rGONR) sheets endows commercial polyurethane (PU) foam with electrical conductivity without altering their porous microstructure. The mechanical properties of the rGONR-coated PU (PGR) foam composites depend strongly on the rGONR content and exhibit poor stability at low content due to the breakage of the rGONR network during cyclic deformation. Introduction of the flexible PDMS coating effectively stabilizes the 3D rGONR network on the foam skeleton, producing excellent mechanical reliability, e.g., reversible compressibility at a compressive strain of 80% for 100 cycles. Moreover, these mechanically stable and porous PDMS modified PGR composites display excellent lipophilic-hydrophobic behavior, which provides good oil/solvent absorption capacity and highly efficient continuous oil/water separation.

A facile template-free one-step synthesis method of ultrathin g-C3N4 nanosheets was developed through thermal polycondensation of melamine. The higher temperature, prolonged time and tightly sealed crucible reaction system contributed to the formation of ultrathin g-C3N4 nanosheets. The as-synthesized g-C3N4 nanosheets were applied to the visible light photocatalytic degradation of RhB. The photocatalytic activity was significantly enhanced with increased calcination temperature from 500 °C to 650 °C and prolonged calcination time from 4 h to 10 h. Interestingly, the obtained ultrathin g-C3N4 nanosheets simultaneously possess high yield and excellent photocatalytic activity. Moreover, g-C3N4 nanosheets can maintain photochemical stability after five consecutive runs. The remarkably enhanced photocatalytic activity can be interpreted as the synergistic effects of the enhanced crystallinity, the large surface area, the reduced layer thickness and size and the reduced number of defects. A new layer exfoliation and splitting mechanism of the formation of the ultrathin nanosheets was proposed. This work provides a new strategy to develop a facile eco-friendly template-free one-step synthesis method for potential large-scale synthesis of ultrathin nanosheets with high yield, high photocatalytic efficiency and stable activity for environmental and energetic applications.

Herein, we present the successful preparation of a new family of porphyrin-functionalized coordination star polymers through the combination of coordination-driven self-assembly and post-assembly polymerization. Their ordered self-assembly behaviour in water and potential applications in photodynamic therapy have been demonstrated.

A platanus-fruit-like manganese monoxide (MnO)/nitrogen-doped porous carbon (MNPC) is prepared by a simple and low-cost method, in which MnO nanoparticles are combined with the polypyrrole-based hydrogel (PPH) derived nitrogen-doped porous carbon (NPC). When used as an electrode, the porous NPC acts as an effective support for the MnO nanoparticles that can provide a high ion storage capacity. Consequently, MNPC shows a good cycling stability and an enhanced rate capability in lithium-ion batteries, and the composite performs better than NPC and bare MnO particles alone. However, in sodium-ion batteries, MNPC exhibits a similar electrochemical behavior as NPC, indicating that MnO nanoparticles are much less active for storing sodium. This is likely because the thermodynamic driving force and redox potential for sodium storage in MnO are much lower than those for lithium storage. Thus, this study helps to thermodynamically reveal the lithiation and sodiation properties of MnO materials.

Carbon nanotubes supported palladium (Pd/CNTs) catalyst displayed excellent activity toward hydrogenation of polystyrene (PS) to produce polycyclohexylethylene (PCHE) with added commercial values. However, its application is limited by the costly catalyst filtration process and energy-consuming elevated agitation speed. Herein, a dense, homogeneous and strongly attached layer of CNTs was decorated on nickel foams and employed as the catalyst support for palladium nanoparticles. Structured catalyst (Pd/CNTs@NF) was directly used as the catalyst stirrer in a rotating foam stirrer reactor (RFSR) for PS hydrogenation. Owing to the enhanced mass-transfer process, the hydrogenation degree reached 68.8%, which was 45.1% higher than that obtained in a slurry reactor using powdered Pd/CNTs catalyst under identical reaction conditions. Outstanding attachment strength of CNTs on the foam and catalytic stability in eight runs of recycling were also demonstrated. This work elucidates the promising feasibility of struc...

The effects of graphene oxide (GO) on the hydration kinetics, pore structure, mechanical properties, and the structure of calcium silicate hydrate (C-S-H) gels were systematically investigated by combinatorial techniques. GO can accelerate the cement hydration, refine the pore structure and increase the polymerization degree of C-S-H gels due to the nucleation effects of GO. The specific surface area of cement paste and the number of gel pores were reduced with the addition of GO. A 3D network structure of GO modified C-S-H gels was originally proposed based on the obtained results that GO could intercalate into the interlayer space of C-S-H gels through ionic bonding with Ca2+ and fill in the gel pores. A small fraction of GO (0.022 wt%) increased the 28 d compressive strength by 16.31%–25.60% at a various water to cement ratios, indicating that GO is a potential nano-reinforcing material for cement composites. The results would provide a well understanding of the reinforcing mechanisms of GO in cement composites and pave a pathway for the design of high-performance cement composites.

Both connate water and the injected water through hydraulic fracturing can coexist with methane inside shale nanopores where two-phase flow possibly occurs. Few studies have been pertaining to two-...

Hydrogel-based flexible strain sensors have shown great potential in body movement tracking, early disease diagnosis, noninvasive treatment, electronic skins, and soft robotics. The good self-healing, biocompatible, sensitive and stretchable properties are the focus of hydrogel-based flexible strain sensors. Dual network (DN) hydrogels are hopeful to fabricate self-healing hydrogels with the above properties. Here, multifunctional DN hydrogels are prepared via a combination of host-guest interaction of β-cyclodextrin and ferrocene with dynamic borate ester bonds of poly(vinyl alcohol) and borax. Carbon nanotubes are used to endow the DN hydrogels with good conductivity. The obtained DN composite hydrogels possess good biocompatibility, stretchability (436%), fracture strength (41.0 KPa), self-healing property (healing efficiency of 95%), and high tensile strain sensitivity (gauge factor of 5.9). The DN composite hydrogels are used as flexible strain sensors to detect different human motions. After cutting, the healed hydrogels also can monitor human motions and have good stability. In addition, the hydrogel sensors may track the respiratory movement of a pig lung in vitro. This work exhibits new ideas and approaches to develop multifunctional self-healing hydrogels for constructing flexible strain sensors.

In situ polymerization of preorganized amphiphilic monomers on various substrates provides a flexible synthetic route to construct high-quality two-dimensional polymers (2DPs) with designed functionalities. However, the detailed polymerization kinetics of these monomers in 2D confinement and their impact on the structural features of 2DPs have not been efficiently explored. Here, using dissipative particle dynamics (DPD) simulations, we unveil the similarity of the polymerization kinetics of the amphiphilic Gemini molecules in both a 2D-confined space and solution and emphasize the key role of the initiator concentration in modifying the morphology of 2DPs. More interestingly, introducing a spacer group into the Gemini monomer facilitates the formation of porous 2DPs. The size and periodic arrangement of pores in these 2DPs could be directly controlled by the Gemini molecular geometries and polymerization kinetics. The insights based on our DPD simulations provide valuable guidelines for the rational design and synthesis of 2DPs from a wider range of amphiphilic molecules.

An integrated technique of hydrothermal pretreatment coupling with deep eutectic solvent (DES) extraction was tailed to cleanly fractionate lignocellulose into three usable forms, i.e., water-soluble hemicellulose, cellulose-rich and lignin fractions, which were further upgraded to three nanomaterials, i.e., activated nanocarbons (ANCs), lignin-containing cellulose nanofibers (LCNFs), lignin nanospheres (LNSs) respectively. Almost 100% hemicellulose was solubilized in the hydrothermal pretreatment, which was used as carbon source to produce ANCs with rather high specific surface area (about 2680 m2 g−1) through in situ carbonation followed by activation. Cellulose-rich fraction was used to produce LCNFs with high aspect ratio (about 150) using facile mechanical refining. While the clean lignin fraction with enhanced amphiphilic properties was used to produce LNSs (223 nm diameter) using self-assembly method. The related mechanism was that condensed lignin could still be extracted by DES due to its excellent lignin solubility. The resulting lignin amphiphilicity provided a powerful driving force to enhance the self-assembly process thus compact LNSs was obtained. Meanwhile, the DES-swelled cellulose structure significantly facilitated the subsequent mechanical disintegration for LCNFs production. In this work, the proposed integrated technique platform realized the complete utilization concept of lignocellulosic biomass, and also provided three high-value nanomaterials product streams for downstream application towards an industrial relevant process.

The dynamic process of synthesizing Janus nanoparticles (JNPs) at a water/oil two-phase interface using a grafting-from reaction is investigated via dissipative particle dynamics simulations. We find that the interfacial tension, the initial monomer concentration, and the reaction probability can greatly influence the microscopic characteristics of JNP structure. It is difficult to synthesize a symmetric JNP with an equal volume ratio between hydrophilic and hydrophobic parts by grafting-from methods unless the physical chemical conditions in the two phases are strictly symmetric, and there is always a disordered domain on the JNP at a two immiscible solvents interface. Interestingly, for certain routes for synthesizing JNPs with a grafting-from method, the higher interfacial tension between the water and oil phases may enhance the degree of disorder of the grafted chains. The asymmetric initial monomer concentration in solution and the reaction probability can be used to control the syntheses of asymmetric JNPs.

Polyurethane elastomer electrolyte (PUEE) represents a promising class of polymer solid electrolytes for the preparation and packaging of flexible devices by anodic bonding. In this work, PUEEs were designed and prepared via a pre-polymerization method and cured at room temperature using polypropylene glycol (PPG), toluene-2,4-diisocyanate (TDI) and 1,4-butanediol (BDO) in the presence of varying amounts of lithium bis(trifluoromethanesulphonyl)imide (LiTFSI). All PUEEs exhibited high thermal stability and conductivity, with the highest ionic conductivity of 9.6 × 10−5 S cm−1 for PUEE6 (n[NHCOO]/Li+ = 1) at 55 °C. The results showed that LiTFSI was dissolved completely in the polyurethane matrix, and the complexing reactions occurred between the lithium ions and the polar groups of polyurethane. After that, the prepared PUEE and the Al sheet were successfully joined by the anodic bonding process. The microstructures of the bonded interface between PUEE and the Al sheet with a clear intermediate bonding layer could be observed in the cross-section scanning electron microscopy (SEM) images, and the elements in each layer were also detected by energy dispersive spectroscopy (EDS), which indicated that the PUEE and the Al sheet were bonded together. The maximum tensile strength for bonded PUEE6/Al was up to 0.45 MPa. All these results demonstrated that the prepared PUEE material would be a promising candidate for the preparation and packaging of flexible devices by anodic bonding.

This study explores the impacts of materials, such as adsorbents and electrodes, on the energy efficiency of a 4-step ESA cycle for CO2 capture. Three types of adsorbents including activated carbon ...

The hierarchical BiOClxBr1–x was synthesized by a simple solvothermal method. The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), UV-visible diffuse reflectance spectroscopy (UV-vis DRS) and Brunauer-Emmett-Teller adsorption method. Compared to pure BiOCl or BiOBr, the BiOClxBr1–x solid solution has enhanced photocatalytic degradation activity for rhodamine B. This phenomenon can be explained to the hierarchical structure, lager specific surface area and appropriate energy gap of the obtained BiOClxBr1–x solid solution. The renewability and stability of photocatalyst were determinated and a possible mechanism of photocatalytic degradation was also proposed.

Fluoride calcium silicate (FCS) are widely used in dental tissue engineering due to their excellent biological properties. This study aimed to develop novel FCS with multiple biofunctions as toothpaste additives. In this study, the preparation of composite FCS, morphologies of the composites and the in vitro biofunctions were investigated. Calcium silicate with 0.7% (wt) fluoride was prepared by co-precipitation method. Pure calcium silicate (CS) was synthesized for controlling study. Biomimetic mineralization study was conducted in simulated body fluid (SBF), the composition, phase structure, apatite formation and morphology were investigated by X-ray Fluorescence Analysis (XPS), X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and transmission electron microscope (TEM). In vitro cell viability studies showed that the fluoride ions promoted cell proliferation and differentiation. This study indicated that FCS shown good bioactivity to induce apatite formation and it could be a promising toothpaste additives with specific biofunction.

Two 3D modular designed coordination polymers, namely, {[H2N(CH3)2]2[Mn(TPT)]}n (1), and {[Cd(TPT)0.5(bib)]·0.5H2O}n (2) (H4TPT = p-terphenyl-2,2″,5″,5‴-tetracarboxylate acid, and bib = 1,3-bis((imidazol-1-yl) benzene) have been synthesized and structural characterized by EA, IR, TG, PXRD. Single-crystal X-ray diffraction analyses reveal that complex 1 is a 3D 4-connected {42.63.8}–sra net with the tiling modular being [42.62.82] = [4a.4b.62.8a.8b] (transitivity is 2451). While complex 2 is a 3D (4,4)-connected {64.82}{66}2–bbf net with tiling modular is [6.82]+[63.8] = [6 c.8a.8b]+[6a.6b.6 c.8a] (transitivity is 2352). The variable-temperature susceptibility of 1 has been investigated. Besides, complex 2 exhibits highly sensitive sensing of FeIII ions in DMF solution.

Graphene oxide nanoribbons (GONRs) were synthesized and functionalized by silane molecules with different hydrophobic end-groups, and silane functionalized reduced GONR (silane-f-rGONR) coated polyurethane (PU) sponge composites were fabricated via a facile dip-coating process. Fourier-transform infrared, Raman spectrum, X-ray photoelectron spectroscopy and scanning electron microscopy demonstrated that silane molecules were successfully grafted onto GONR sheets, thus producing the ability to tune surface and physical properties of PU sponge from insulating and hydrophobic to conductive and super-hydrophobic. Cyclic compression and strain-induced electrical resistance change tests indicated that the porous silane-f-rGONR coated PU (silane-f-rGONR@PU) sponge composites exhibited excellent mechanical elasticity and durability and high sensitivity of resistance change. Furthermore, the two types of silane modified sponges showed different super-hydrophobicity and tunable oleophilicity/oleophobicity. Compared to the rGONR@PU composite with poor oil/water separation at dynamic state, these porous silane-f-rGONR@PU composites not only possessed excellent oil/solvent absorption capacity and selective oil/water separation at static state, but also showed good continuous oil/solvent pumping collection with high recyclability (>97% after 10 cycles) and outstanding oil/water separation efficiency at the dynamic shaking state. This work provides a new strategy for fabricating the super-hydrophobic, electrically conductive and mechanically flexible porous rGONR based composites, showing promising application in strain sensor and oil pollution remediation fields at different environmental conditions.

The polydopamine (PDA) coating was used to modify the surface of the PbO2/TiO2 nanotube arrays (PTNAs) by impregnation method. The obtained PDA-PbO2/TiO2 nanotube arrays (PPTNAs) coating exhibited a sandwich structure and used as anode for photoelectrochemical degradation of toluene. Generally, due to the symmetric structure and conjugation of methyl with benzene ring, the degradation of toluene was difficult to carry on. Our results show that the rate of toluene degradation can reach up to 66% at the surface of PPTNAs coating anode, it is much higher than that of the TiO2 nanotube arrays coating anode, 17%. The reduction product at cathode, hydrogen, was also measured, which is one of the valuable source of energy. In the coupled effect of applied voltage and photocatalysis on the PPTNAs anode, the degradation of toluene was carried out smoothly. The introduction of lead dioxide nanoparticles on the coated anode possessed favorable electronic conductivity in strong acid, which is benefit for a high rate of electrons transportation at the interface of TiO2 and lead dioxide. The excellent corrosion resistance of PPTNAs coating further ensured the effective degradation of toluene with long-term stability. Meanwhile, the unique adhesion of the outer PDA coating increased the contact opportunities between toluene molecules and the anode surface, and enhanced the photocatalytic activity of the PPTNAs coating anode. The applied voltage suppressed the recombination of electron-hole pairs and provided abundant reaction sites. All of these increased the photo-electro catalysis of toluene degradation. The new fabricated anode material shows good prospective application of cleaning up refractory pollutants and the resource utilization.

A series of new platinum (II) complexes were obtained, where 2-phenylpyridine derivatives are used as the main ligand and 5-substitued tetrazole are used as the auxiliary ligand. Although the complexes with one or without any peripheral flexible around rigid core do not reveal liquid crystallinity, the complexes with three flexible alkoxy chains attached to 2-phenylpyridine and tetrazole display liquid crystalline property. In order to investigate the self-assembly behavior of the liquid crystalline complexes, their polarized luminescence is researched, and the maximum polarization ratio can reach 7.1 at room temperature. Moreover, the ambipolar carrier mobility was measured in these neutral cyclometalated platinum (II) complexes, the electron mobility and hole mobility can reach 3.3 × 10 −4 cm 2 /(V·S) and 6.3 × 10 −5 cm 2 /(V·S), respectively.

Graphene oxide (GO) is an attractive candidate for use as a nano-reinforcement in cement composites. However, a prerequisite for GO to fulfill its function is the uniform dispersion of GO throughout the cement matrix. In this paper, the dispersion behavior of GO modified by lignosulfonate (LS), polycondensate of β-naphthalene sulfonate formaldehyde (PNS), and polycarboxylate superplasticizer (PC) in cement pore solution was investigated by a combination of visual observation, optical microscopy and transmission electron microscopy (TEM). Results show that GO modified by PC exhibited better dispersion in cement pore solution than LS and PNS. Zeta potential analysis demonstrated that LS and PNS failed to adsorb onto the GO surface when pH > 11, while successful attachment of PC to GO was achieved even in the alkaline environment. The dispersion mechanisms of PC modified GO were thought to be a combination of covering the surface of GO, lowering the free Ca2+ concentration and impeding the cross-linking of Ca2+ due to steric hindrance effect of PC. With the addition of PC modified GO, the fluidity and mechanical strength of cement composites were improved significantly, indicating that this dispersion route can be successfully used for the preparation of GO reinforced cement composites.

The microstructured and hyperdoped silicon as a superior photoelectric and photovoltaic material is first studied as a gas-sensing material. The material is prepared by femtosecond-laser irradiation on selenium-coated silicon and then fabricated as a conductive gas sensor, targeting ammonia. At room temperature, the sensitivity, response time, repeatability, distinguishability, selectivity, and natural aging effect of the sensor have been systematically studied. Results show that such black silicon has good potential for application as an ammonia-sensing material. On the basis of its unique optoelectronic properties, an additional optical drive is proposed for the formation of an optical and electric dual-driven sensor, which is achieved by asymmetric light illumination between the two electrode regions. In a certain range of applied voltage, the sensitivity is enhanced dramatically and even tends to be infinite. For the aged device with degraded sensitivity, a two-order increment is obtained for 500 ppm of NH

The development of highly-efficient, inexpensive, and stable electrocatalysts as alternatives to platinum-based materials for the oxygen reduction reaction (ORR) is crucial to various energy storage and conversion systems, such as metal–air batteries and fuel cells. Herein, we have successfully prepared three kinds of hierarchically porous nitrogen-doped carbons with different morphologies (particles, nanowires, and nanoribbons) through a carbon dioxide activation process. The porous properties and catalytic performance of the nitrogen-doped porous carbons are dramatically and clearly improved through changing the morphology of polypyrrole precursors. Among these nitrogen-doped porous carbons, the nitrogen-doped and nanostructured carbon with the morphology of nanoribbons possesses the highest specific surface area (1130 m2 g−1) and displays the best ORR activity with the largest electron transfer number (3.67) and the most positive onset potential (0.86 V vs. RHE) in oxygen-saturated aqueous KOH solution (0.1 M). This enhanced ORR performance can be attributed to nitrogen-doping, a hierarchically porous structure, and large specific surface area.