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Commercial lithium sulfur batteries are hindered by unstable and unreliable cycling performances due to the dissolution and shuttle of lithium polysulfides. Defect engineering with plentiful active sites and high surface binding energies to restrain polysulfides dissolution and promote the redox conversion polysulfides. Here, we present a nano carbon intercalated by W18O49 nanorods composite materials as functional sulfur host. With high W/O ratio of 0.367 in tungsten oxide famliy (WOx), W18O49 achieves abundant oxygen vacancy in intrinsic atomic structure. These oxygen vacancies not only provide stable active sites to stabilize the Li2S but also immobilize polysulfides by strong coulombic interactions of W-S and Li-O bondings. Accordingly, this cathode achieves stable long cycling performance with decay rate of 0.038 % per cycle at 2 C for 1200 cycles. With high sulfur loading of 6.4 mg·cm−2, the cathode also shows stable cycling at 0.2 C for 150 cycles. This immobilizations of polysulfides by oxygen vacancy engineering in W18O49 is referential for developing commercial useable Li-S batteries.

Solar-driven water evaporation is an effective approach for using solar energy to purify seawater and wastewater. However, the high energy requirements of bulk water evaporation fundamentally restrict the practicality of solar freshwater production. Herein, we demonstrate an efficient hierarchical solar evaporator by combining polydopamine (PDA) and Ti3C2Tx MXene (MX) with a cellulose network skeleton of delignified wood (DW). By integrating activated water in a hydrated cellulose network and the synergistic photothermal effect between PDA and MX, the obtained PDMX@DW evaporator achieved a high evaporation rate of 2.08 kg m−2 h−1 and energy efficiency of 93.6% under 1 sun illumination. Differential scanning calorimetry and dark evaporation experiments indicated that the water in PDMX@DW exhibited a lower vaporization enthalpy (1915 J g−1) than bulk water (2440 J g−1). Raman spectral analysis and density functional theory calculations were used to investigate the structure of water molecules in the cellulose network, and it turns out that high contents of weakly hydrogen-bonded intermediate water were the most likely origin of the reduced vaporization enthalpy. More importantly, due to the interactive cellulose network structure and increased water supply rate, PDMX@DW exhibited excellent salt resistance and long-term stability in high-concentration brine. This work provides an effective method for breaking the evaporation limitation of the traditional wood-based evaporator and improving its salt resistance.

The severe problem of water scarcity has led to the derivation and rapid development of solar vapor generation (SVG) technology. However, high cost, short-term stability in harsh environments, and potential secondary pollution restrict the practical application of most solar evaporators, especially in economically underdeveloped areas. Herein, we design a low-cost and long-term stable sponge evaporator by combining carbonized pomelo peel particles (CPPs) with chitosan (CS) and bamboo fibers (BFs) for efficient solar vapor generation. Due to the interactive macroporous architecture formed by BF's random interspersion in chitosan lamellae and the excellent CPP solar absorbers, the obtained robust CS/BFs/CPPs sponge evaporator exhibits a water evaporation rate of 2.317 kg m−2 h−1 with an energy conversion efficiency of 89.23% under one sun illumination. In addition, this sponge evaporator can work in harsh water environments such as acid–base solutions, dye solutions, and high salinity brine for long periods of time because of the stable interactive structure. More importantly, since all green materials for constructing the evaporator belong to the natural world, we demonstrate, the first example of ageing evaporator that can be reutilized and transformed into the soil. This work not only highlights the potential for developing low-cost and long-term durable solar evaporators but also contributes to the research direction for recycling and reutilization of ageing evaporators.

To enhance the interface bonding of polyimide (PI)/carbon fiber (CF) composites, CFs were functionalized by introducing a polydopamine (PDA) transition layer, whose active groups provide absorption sites for the growth of molybdenum disulfide (MoS2) nanosheets and improve the bonding strength with PI. Uniform and dense MoS2 nanosheets with thicknesses of 30–40 nm on the surface of the PDA@CF were obtained via a subsequent hydrothermal method. As a result, the interface between the CF and the PI matrix becomes more compact with the help of the PDA transition layer and MoS2 nanosheets. This is beneficial in forming PI/CF-MoS2 composites with better thermal stability, higher tensile strength, and enhanced tribological properties. The lubricating and reinforcing effects of the hybrid CF-MoS2 in the PI composite are discussed in detail. The tensile strength of the PI/CF-MoS2 composite increases by 43%, and the friction coefficient and the wear rate reduce by 57% and 77%, respectively, compared to those of the pure PI. These values are higher than those of the PI/CF composites without MoS2 nanosheets. These results indicate that the CF-MoS2 hybrid material can be used as an additive to improve the mechanical and tribological properties of polymers.

Rational design and synthesis of hollow core–shell hetero-structures with high complexity still remains challenging for high gas-sensing performances. Here, ZIF-8@ZnO (zeolite imidazolate framework-8) core–shell material was synthesized using an easy-to-use hydrothermal reaction. ZnO is a kind of homologous metal oxide of ZIF-8 material. Therefore, without adding other zinc salts, the formation of ZIF-8@ZnO was completed in a one-pot reaction. Then a series of morphology and structure analysis including XRD, BET, SEM, EDX, etc. were carried out to study the positive effect of ZIF-8 film on the sensing performance of ZnO nanospheres. The results show that the ZIF-8 film uniformly covers the surface of porous ZnO nanospheres with a diameter of about 400 nm, forming a core–shell structure. Compared to the other volatile organic compounds (VOCs), ZIF-8@ZnO shows a higher sensitivity and selectivity to 50 ppm ethanol gas at an operating temperature of 220 °C, which can achieve 13.8. This is almost 2.7 times that of pure ZnO nanospheres (5.1). The obtained results show that ZIF-8@ZnO core–shell material not only greatly improves the sensitivity of the sensor, but also enhance the selectivity of ethanol gas sensing.

Acetone, as one of the volatile organic compounds, is harmful to human health. Thus, fast detection at an early stage plays a vital role. ZnSnO3 shows the merit for a wide range responsivity to VOCs, but the pure ZnSnO3 has slow response-recovery speeds. Herein, the sensors based on urchin-like ZnSnO3/α-Fe2O3 hierarchical hollow microspheres were synthesized by a simple two-step liquid-phase reaction. Porous α-Fe2O3 nanowires with lengths of about 30 nm and diameters of around 2.5 nm were densely anchored on the surface of ZnSnO3 microspheres, forming “urchin-like” geometries, which increased the specific surface area and supplied more active sites for the fast adsorption–desorption of gas molecules. An excellent gas sensing response value (14.24) and ultra-fast response-recovery times (3/8 s) have been recorded in as-obtained urchin-like ZnSnO3/α-Fe2O3 composite sensors at 200 °C. Compared with the pure ZnSnO3 and α-Fe2O3 sensors, the ZnSnO3/α-Fe2O3 sensor displayed an obvious enhancement in gas sensing properties for acetone, which can be put down to high surface area, porous nanostructure, and the synergistic effect of ZnSnO3 and α-Fe2O3.

Design and fabrication of structurally optimized three-dimensional porous materials are highly desirable for engineering applications. Herein, through a facile bidirectional freezing technique, we prepared superelastic biomass sponges in air and underwater, which possess biomimetic porous sandwich-like architectures with lamellar layers interconnected by porous microstructures, similar to the structure of rice stems. This distinctive architecture was obtained by incorporating Typha orientalis fibers (TOFs) and graphene oxide (GO) nanosheets into sodium alginate (SA) matrix, in which SA flakes and GO nanosheets were intimately grown along TOFs. The porous sandwich-like microstructure allows stress to be distributed throughout the lamellar to avoid stress concentration and endows SA/TOFs/GO sponge with excellent mechanical compressibility and recoverability. Especially, underwater superelasticity and superoleophobicity of the sponge facilitates removal of water-miscible contaminants or oil/water separation with high efficiency. This novel strategy for the design biomimetic architecture of superelastic biomass sponge can promote its application for protecting environment.

To realize simultaneous removal of oils and water-miscible dyes from emulsions, a versatile carbon/graphitic carbon nitride (g-C3N4) aerogel with high compressibility and underwater superoleophobicity was fabricated by in situ pyrolysis of urea on the surfaces of cotton fibers. The surfaces were densely covered with a layer of g-C3N4 nanoparticles, leading to the aerogel with underwater superoleophobicity towards oils and organic solvents. The aerogel can be applied for wastewater purification with high flux and removal efficiency only driven by gravity. Various emulsions, dye wastewaters, and even their mixtures can be effectively purified by the aerogel with excellent recyclability. The prepared carbon/g-C3N4 aerogel is believed to have great potential for practical wastewater purification.

Hybridizing nanostructured metal oxides with grapheme oxide (GO) is highly desirable for the improvement of gas sensing performance of gas sensors. Herein, we develop an in situ fluorine directed solution process combined with heat treatment to grow highly ordered, porous α-Fe2O3 nanorods arrays (NRAs) onto graphene oxide (GO) sheets, resulting in flexible three-dimensional nanostructures. The α-Fe2O3 NRAs have heights of ∼50 nm and widths of 10–20 nm, which are densely and vertically attached to both sides of GO sheets, thereby generating an interesting “blanket-like” geometry. When tested as sensing materials for gas sensors, the nanocomposite displays a high sensitivity of 19.14 toward 50 ppm acetone at a work temperature of 220 °C, which was 5.4 times of that of α-Fe2O3. Even after 50 days, a stable sensitivity as high as 18.9 toward 50 ppm acetone could be maintained. The improved high sensitivity, fast response and recovery, and extraordinary stability of GO/α-Fe2O3 can be attributed to the highly ordered, porous structure and the synergistic effect between α-Fe2O3 and GO.

Hierarchical porous α-Fe2O3/TiO2 nanorod@core-shell microspheres were synthesized by a facile one-step hydrothermal approach without templates or surfactants. The as-obtained α-Fe2O3/TiO2 nanorod@core-shell microspheres had an average diameter of 3.5 μm. Porous nanorods, with an average length of 1.5 μm, were randomly grown on the core-shell microsphere surfaces. The morphology, microstructure, and composition of the α-Fe2O3/TiO2 heterostructures were characterized by various analytical techniques. Changes in the morphology and composition of the microspheres had an effect on the final gas sensing performance. Gas sensors based on the porous nanorod@core-shell α-Fe2O3/TiO2 microspheres exhibited an excellent gas-sensing performance, with markedly enhanced responses in comparison with the pristine α-Fe2O3 sensor. The response of the porous nanorod@core-shell α-Fe2O3/TiO2 microspheres to 20 ppm acetone was approximately 34, which was 2.7 times higher than that of pure α-Fe2O3 at 220 °C. Furthermore, the sensor could be easily recovered to its initial state following a short exposure to fresh air. The remarkably enhanced acetone-sensing performance was attributed to the unique porous nanorod@core-shell microsphere morphology, the strong interfacial interaction between TiO2 and α-Fe2O3, and the presence of α-Fe2O3/TiO2 heterojunctions. Thus, the prepared porous nanorod@core-shell α-Fe2O3/TiO2 microspheres sensors showed an outstanding performance in acetone detection.

In order to improve the high temperature sensitivity of α-Fe2O3 based gas sensor, the porous α-Fe2O3 nanorods@graphite nanocomposites were synthesized using a simple low temperature hydrolysis method. A series of analyses were performed to characterize the morphology, structure and composition. As a result, uniform porous α-Fe2O3 nanorods with a length of about 200–300 nm directly grown on the surface of graphite nanoplatelets. When tested as sensing materials for gas sensors, the nanocomposites display a high sensitivity of 16.9 toward 50 ppm acetone at a work temperature of 260 °C, which was 2.2 times of that of pure α-Fe2O3. Even at a work temperature of 320 °C, a stable sensitivity as high as 10.4 toward 50 ppm acetone could be maintained. The improved high temperature sensitivity of porous α-Fe2O3 nanorods@graphite nanocomposites can be attributed to p-n heterojunction, the porous structure of α-Fe2O3 nanorods, the high temperature stability of graphite and large specific surface areas.

Hierarchical oxide nanostructures had proved their promising features in gas sensing due to their high surface areas and well-aligned nanoporous structures containing less agglomerated configurations. In this study, a facile method was developed to prepare Ag/α-Fe2O3 microspheres using α-FeOOH microspheres as precursor and AgNO3 as Ag resource. Various characterization techniques were employed to identify the structures and morphologies of the hybrid nanostructures. The results revealed that Ag nanoparticles with diameters of 5 nm formed on the surface of hollow α-Fe2O3 spheres were composed of primary nano-sized particles. The ethanol sensing properties of pure α-Fe2O3 and Ag/α-Fe2O3 microspheres were evaluated and Ag/α-Fe2O3 microspheres showed higher responses towards ethanol when compared to other gases, such as toluene, ammonia, acetone, and formaldehyde. The response of Ag/α-Fe2O3 microspheres to 50 ppm ethanol was estimated to ∼11.2, which was 1.7 folds higher than that of pure α-Fe2O3 at 240 °C. Furthermore, the sensor could easily be recovered to its initial state in short periods after exposure to fresh air. The addition of Ag served as an active catalyst, creating more active sites believed crucial for enhancing sensitivity.

Here we report an integrated reduced graphene oxide/polypyrrole hybrid aerogel with highly efficient photodegradation performance and ultrahigh solar-powered water evaporation for simultaneous freshwater production and decontamination from complex wastewater. The nanohybrids were successfully fabricated by the combined hydrothermal reduction and freeze-drying process. The π-π interactions between two components not only prevent the stacking of reduced graphene oxide nanosheets to endow aerogels with abundant water transport channels and ideal mechanical stability, but also facilitate the interactions with organic molecules to realize high removal efficiency toward volatile organic compounds (VOCs). The wide-spectrum light harvesting, photothermal effect and solar-driven photocatalysis in the hybrid aerogel are beneficial for the synergistically enhanced thermal-assisted photodegradation toward VOC-contaminated water with a water evaporation rate of 2.08 kg m−2 h−1 and a phenol removal efficiency of 94.8%. Our findings may help the development of novel functional nanostructures for applications in environmental remediation and solar steam generation.

Exhaled acetone in the non-invasive diagnosis of type Ⅰ diabetes is one of the representative biomarkers. In this work, the Ag nanoparticles (NPs) modified Fe3O4/rGO composites was synthesized through a simple hydrothermal reaction, which could be a potential acetone sensor for painless and rapid breathing analysis. Through SEM and TEM, it was found that Ag nanoparticles were uniformly distributed on the surface of rGO sheets embedded in rod-shaped Fe3O4. Compared with the matrix material, the Ag/Fe3O4/rGO sensor shows good selectivity to acetone, and the cross-response to interfering gases (methane, toluene, ammonia, ethanol) is negligible. Meanwhile, the Ag0.1/Fe3O4/rGO sensor shows an ultra-high response of 35.81–50 ppm acetone at 220 °C, which is 2.5 times higher than that of pure Fe3O4/rGO. The improvement of Ag/Fe3O4/rGO nanomaterial in acetone sensing properties comes from the chemical and electronic sensitization effects of Ag nanoparticles, and this nanostructure generates more oxygen species and active sites, and improves the gas response. As a result, Ag0.1/Fe3O4/rGO has a good response and selectivity to acetone vapor, indicating its potential application in breath acetone analysis.

Nickel (Ni) nanocrystals with a flower-like shape were successfully fabricated through a low temperature solution-phase approach without using any template or surfactant. The structures and morphologies of the as-synthesized Ni nanocrystals were systematically characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Brunauer–Emmett–Teller surface analysis. Further, the magnetic property was also analyzed using a vibrating sample magnetometer (VSM). The characterization results showed that the entire structure of the products with diameter of around 500 nm was composed of several nanocones connected with each other through the center to form the three-dimensional hierarchical flower-like structures. Moreover, the orientation and morphology of the products could be carefully controlled by adjusting the reaction temperature, the growth time, and the reaction solvent. Furthermore, a possible formation mechanism of the hierarchical flower-like Ni nanostructures was also proposed based on the detailed characterization analysis. Besides, the series of Ni nanocrystals was studied for the catalytic hydrogenation of toluene to methylcyclohexane. It was found that the hierarchical flower-like Ni nanostructures obtained at 80 °C for 2 h showed an optimal catalytic performance among all the Ni catalysts tested, and correspondingly a 100% hydrogenation of toluene was achieved with in 30 min under the relatively mild reaction conditions. The merits including excellent durability, sound productivity, and superior catalytic performance make the hierarchical Ni nanocrystals as promising catalysts for the practical industrial application.

The graphene oxide (GO) nanosheets/carboxyl-functionalized multi-walled carbon nanotubes (CNTs) hybrids (GO/CNTs) were synthesized via vacuum filtration solution hybrid dispersion and the corresponding GO/CNTs/polyimide (GO/CNTs/PI) nanocomposite films were facilely prepared by in situ polymerization. Both the thermal stability, mechanical and tribological properties of GO/CNTs/PI nanocomposites were greatly improved compared with those of pure PI due to the homogeneous dispersion of GO/CNTs and the strong interfacial covalent bonds between GO/CNTs and the PI matrix. Furthermore, GO/CNTs/PI nanocomposites exhibited the much lower friction coefficient compared to that of PI composites with the same loading of GO or CNTs only, suggesting the synergistic effects of GO/CNTs hybrids on the tribological properties of polyimide nanocomposites, especially the weight ratio of GO and CNTs was 3:1.

Environmentally friendly polypyrrole (PPy) catalysts with conjugated nanostructures for superior photophysical and photoelectric applications are developed. The high coplanar structure via α-α connection is benefit for the transferring of photo-induced electron and improving the life of the light generated carrier. Importantly, the energy level structure of conjugated polymers was obtained via theoretical calculation and the photocatalytic mechanism of PPy photocatalyst was illuminated in detail. O2− are the main radical responsible for the degradation of MO. Moreover, conjugated PPy photocatalysts are stable with cycling. Compared to P25 and g-C3N4, PPy showed excellent photocatalytic performance for degradation of organic pollutants in full spectrum and visible light, the reaction rate constants of PPy are 4.27 and 5.31 times as much as the P25, respectively. Furthermore, PPy also exhibited effective photocatalytic performance towards different organic pollutants. These results obviously open interesting perspectives of using conjugated polymer and provide theoretical guidance for designing new organic photocatalysts to solve the energy and environment issues.

A hydrothermal route is developed for the synthesis of MoS 2 /graphene oxide (GO) composites based on the hydrothermal reduction of Na 2 MoO 4 and GO sheets with l -cysteine. The MoS 2 /GO composites in improving friction and wear of the sunshine oil on sliding steel surfaces under low or high applied load were demonstrated. In tests with sliding steel surfaces, the sunshine oil that contains small amounts of MoS 2 /GO composites exhibited the lowest specific friction coefficient and wear rate under all of the sliding conditions. Scanning electron microscopy and energy dispersive spectrometer performed to analyze the wear scar surfaces after friction confirmed that the outstanding lubrication performance of MoS 2 /GO composites could be attributed to their good dispersion stability and extremely thin laminated structure, which allow the MoS 2 /GO composites to easily enter the contact area, thereby preventing the rough surfaces from coming into direct contact.

A simple wet chemical reduction method was developed to prepare in situ growth of Cu nanoparticles (NPs) decorated on polydopamine (PDA) functionalized graphene oxide (GO) nanosheets. The immobilized Cu NPs with diameters of 10–15 nm were uniformly distributed on PDA/GO nanosheets. The PDA layer on the surface of GO not only provides an activated platform for the uniform Cu NPs immobilization, but also remains abundant functional groups in Cu/PDA/GO nanocomposites even if after Cu NPs decorating on PDA/GO surface, which give rise to good dispersibility of Cu/PDA/GO nanocomposites in the base oil. In tests with sliding steel surfaces, the soybean oil with 0.1 wt% Cu/PDA/GO nanocomposites exhibited the lowest friction coefficient under all of the sliding conditions. Optical microscope images of the wear scar of the steel disc showed that Cu/PDA/GO nanocomposites exhibited higher antiwear capability than Cu NPs, GO and Cu/GO. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy (Rm) of the worn surface lubricated by the soybean oil with Cu/PDA/GO nanocomposites showed that formation of low shear strength tribofilms containing Cu/PDA/GO nanocomposites and its self-lubricating property was key factor in reduction of the friction and protection against wear and deformation.

Fe3O4-TiO2 heterostructures were synthesized through co-precipitation method based on TiO2 nanobelts. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibration sample magnetometry (VSM) were used to characterize the heterostructure nanocomposites. The results of XRD proved that the TiO2 nanobelt was anatase which was the most suitable crystal form for photocatalysis. SEM and TEM analysis indicated that Fe3O4 nanoparticles were adhere to TiO2 nanobelts which have one-dimensional structure with 100–200 nm in width. The VSM measurements showed that the photocatalyst can be easily recovered by an extemal magnetic field. X-ray photoelectron spectroscopy (XPS) of Ag@Fe3O4-TiO2 nanocomposites studies confirm that Ag is in Ag0 state. Finally, the photodegradation of rhodamine B (RhB) by the obtained magnetic photocatalyst was investigated via UV–vis absorption spectra. The photocatalytic activity of the composites was observed to be lower compared to bare TiO2 due to the higher degree of recombination reactions after combined with Fe3O4 nanoparticles. After coated the composite of 15% Fe3O4-TiO2 with Ag, the new nanocomposite of Ag@Fe3O4-TiO2 can be easily recovered after photocatalysis by an extemal magnetic field and showed enhanced photocatalytic activity. The mechanisms for the exhibited enhanced photocatalytic effect of Ag nanoparticle decorated Fe3O4-TiO2 nanocomposites with surface heterostructures are discussed.

The development of water-based lubricants with well dispersed ultrafine particles is in high demand. In this article, graphene oxide (GO) nanosheets/carboxyl-functionalized multi-walled carbon nanotubes (MWCNTs–COOH) hybrids have been synthesized via vacuum filtration of a solution hybrid dispersion, as additives for water-based lubricants. The tribological performance of GO/MWCNTs–COOH hybrids in water was systematically investigated. The lubrication properties of water-based lubricant can be significantly improved by adding GO/MWCNTs–COOH hybrids in comparison with adding only GO nanosheets or MWCNTs–COOH as lubricant additives. Notably, the water with as little as 0.7 wt% of GO/MWCNTs–COOH hybrids exhibits the best lubrication performance in terms of friction and wear reduction. This unique tribological performance of GO/MWCNTs–COOH hybrids in water suggests the existence of a synergistic effect of GO and MWCNTs–COOH on reducing friction and wear.

Monitoring ethanol is importance to our life. Here, CuO/ZnSnO3 hollow microspheres were synthesized through in-situ precipitation method. CuO/ZnSnO3 was characterized by XRD, XPS, SEM and TEM. The characterization results showed that CuO/ZnSnO3 hollow microsphere with a radius of 0.8–1.4 μm. The sensing performances of the as-prepared nanocomposites were examined and compared with ZnSnO3 and CuO. Gas sensing results revealed that the 8% CuO/ZnSnO3 sensor exhibits excellent ethanol response (Ra/Rg = 131–100 ppm), which was 3–3.5 times higher than that of ZnSnO3 and CuO at the optimal operating temperature (160 ℃), respectively. The simple production process and superior gas response make CuO/ZnSnO3 applicable to more occasions where ethanol exists. The improved performance can be attributed to the p-n heterojunction between CuO and ZnSnO3.

Unique ZnSnO3/SnO2 concave microcubes with different doping amount of SnO2 (5 wt%, 10 wt%, 15 wt%) were obtained by a simple hydrothermal reaction. A sequence of experiments based on different ratios of Na3C6H5O7·2H2O and SnCl4·5H2O were carried out, exploring the reason for the formation of concave microcube. Many SnO2 nanoparticles were densely anchored on the rough surface of the as-obtained concave microcubes, which further increased the specific surface area and provided more active sites for the adsorption-desorption of gas molecules, delivering outstanding gas sensing performances. A high gas sensing response value (18.3), fast response/recovery time (5/6 s), good reproducibility and selectivity as well as extraordinary stability have been recorded in the case of ZnSnO3/10 wt%SnO2 composites. In comparison with the pure ZnSnO3 and ZnSnO3/SnO2 sensors with other ratios (5 wt%, 15 wt%), the ZnSnO3/10 wt%SnO2 sensor displayed a distinct enhancement in gas sensing properties toward acetone, which can be owed mainly to increased high surface to volume ratios, the presence of oxygen vacancies and the synergistic effect between ZnSnO3 and SnO2.

To enhance properties of polyimide (PI)/carbon fabric (CFC) composites, polyaniline nanofibers (PANI-NF) and polyaniline film (PANI-F) were success fully grown on the CFC surfaces to tune the interface with PI. A conformal PANI-F on the CFC surface was formed using the high concentrations of aniline and oxidant, while at the lower concentration, a large amount of interconnected PANI-NF with the average length of about 150 nm and the diameters of 30–50 nm was obtained. Through the chemical reaction between polyamic acid and PANI, interface compatibility of PI and CFC was improved. Meanwhile, PANI-NF on the fiber surface provided an effective mechanical interlocking at the interface. As a result, PI/CFC-PANI-NF composite exhibited the best thermal, mechanical and tribological properties. The tensile strength and modulus of PI/CFC-PANI-NF composite increased by 48.2% and 35.1% respectively compared to PI/CFC-PANI-F composite, while the wear rate declined sharply by 60%. Therefore, the growth of PANI on CFC is an ideal way to obtain high-performance composite that can meet demanding conditions.

Polymer-based composites reinforced by lubricated fillers have aroused wide concern in the field of tribology. In this manuscript, the effect of graphene oxide (GO) as lubricated filler on the tribological behaviors of polyimide (PI)/graphene oxide (GO) nanocomposites prepared by hot press molding method was investigated under seawater to provide a practical guidance for the use of the polymer-based composites in ocean environment. It was found that the incorporation of GO could greatly improve the wear resistance of pure PI under seawater lubrication, especially when the content of GO was about 0.5 wt%. This was due to the lubricated effect of GO. In addition, PI/GO nanocomposites exhibited better friction and wear properties under seawater-lubricated condition than that under dry friction condition because of excellent lubricating effect of seawater. Optical photographs of the worn surface morphology had revealed that the main wear mechanism of the PI/GO nanocomposites was slight abrasive wear.

The nanocomposites of g-C3N4 supported by Fe3O4 nanoparticles (Fe3O4/g-C3N4) have been fabricated through a simple hydrothermal route in a water–ethanol system. The nanocomposites were characterized by X-ray diffraction, and transmission electron microscopy, Fourier transform infrared, and thermogravimetric analysis, respectively. The results showed that g-C3N4 nanosheets were decorated randomly by Fe3O4 nanoparticles with average diameters of 7 nm. The photocatalytic activities were evaluated in terms of the efficiencies of photodecomposition of Rhodamine B in aqueous solution under visible light illumination. The as-synthesized Fe3O4/g-C3N4 nanocomposites showed unprecedented photodecomposition efficiency compared with pure g-C3N4 under visible-light. The Fe3O4/g-C3N4 nanocomposites with improved photocatalytic activities would have a great potential in removing organic dyes from polluted water.

Monodisperse Zn-doped α-Fe 2 O 3 microcubes were prepared via a facile hydrothermal method with zinc ions as the structure-directing agents. The observations of FE-SEM and TEM showed that the obtained sample has a quasi-cubic shape with an edge length of about 250 nm. It can be found that the dosage of Zn 2+ in the solution had a remarkable effect on the morphology of as synthesized samples. The element analyses of the fabricated microcubes were carried out by XPS and EDS. The investigation on the evolution formation revealed that Zinc ions were critical for controlling the assembly of microcubes. Moreover, the gas sensors based on Zn-doped α-Fe 2 O 3 microcubes were fabricated and the gas sensing performances were investigated. It was found that the gas sensor exhibited high response, good selectivity, fast response and recovery time to acetone at the working temperature of 240 °C.

The inefficient cleanup of viscous heavy oil is thought as a worldwide problem because of its poorer fluidity at room temperature. Herein, we make full use of the photothermal performance to harvest solar energy and convert heat into heavy oil, thus reducing significantly oil viscosity and realizing rapid oil remediation. Specially, the polydopamine as photothermal components, titanium dioxide and perfluorodecyltrichlorosilane as superhydrophobic/superoleophilic source are introduced into the melamine-formaldehyde sponge by deposition method. To be applicable in the marine environments with winds and waves, the bottom side of this sponge subjected to UV irradiation is transferrable from superhydrophobicity to superhydrophilicity. The Janus sponge can keep the balance of movement and never overturned under the action of wind force, thereby enabling this sponge to absorb consecutively spilled heavy oil from marine system. With one simulated solar irradiation, the top and bottom of Janus sponge are heated to a suitable temperature of 90.7 and 70.2 °C, respectively. Relied on these advantages, the Janus sponge can effectively reduce the viscosity of spilled heavy oil and enhance its fluidity, which allow for quick heavy oil absorption up to nearly 12 times of own weight. Meanwhile, it can be also compressed for recycled uses.

In this study, green and high-efficient ionic liquids crystal (ILC)-assisted hydrothermal exfoliation method was developed for exfoliation and functionalization of fluorinated graphene (FG). The proposed method was efficient for exfoliating FG from bulk fluorinated graphite (FGi) at yield reaching 48%. Meanwhile, the reliable interaction between FG and ILC led to noncovalent functionalization of exfoliated nanosheets, where exfoliated FG suspensions were highly stable at room temperature for more than three months without formation of agglomerates. The tribological properties of exfoliated FG nanosheets were then tested as lubricating additive and showed significant decrease in friction coefficient by 82% when compared to pure water. On the other hand, well-dispersed homogeneous FG/-poly (vinyl alcohol) (PVA) composite film with robust mechanical properties and photothermal effects were fabricated thanks to the excellent dispersibility of the FG nanosheets.

A rapid seeded growth was observed on nanosized (50–100 nm) titanium silicalite-1 (TS-1) zeolites (denoted as nano-TS-1) with a recovered mother liquid. Only 3–8 h were required to synthesize the zeolites with a yield above 80% at 393–423 K in a hydrothermal condition. Such a high efficiency is superior to the conventional synthesis, which produces the sub-micron (100–200 nm) TS-1 within 8–36 h without any seeding effect by the mother liquid. The synthesis of the nano-TS-1 was relatively insensitive to the synthesis condition, though dependent on the seeding effect, water content, and titanium precursors. A possible explanation is proposed for the formation of the MFI type TS-1 zeolites based on the ESI-MS spectra analysis on the synthesis gel. The basic building units (BBU), composed of the active SiO2 species, especially the monomer silicic acid, were firstly induced to the polymerization and formed the special secondary building units (SBU), including certain critical SimOn species for constructing. These SBUs were assembled to mfi cages (as a compositing building unit) and pentasil-type chains, fabricated as a MFI-type crystal. The recovered mother liquid not only provided certain amount of SBU-type SixOy species that accelerated the nucleation and formation of the zeolites, but also intensified the super-saturation of the active SiO2 species that would favor the nanosized zeolites. Such nanoscale size endows the TS-1 zeolites with large external surface area (148 m2/g) and zeta potential value (−47 mV), accounting for the novel dispersion of the nanoparticles. The composition of TiO2/SiO2 in the nano-particles created superior electro rheological properties to those of the conventional sub-micron TS-1 zeolites.

Fungus-like molybdenum disulfide (MoS2) nanosheets with a thickness of a few nanometers have been successfully synthesized via one-pot hydrothermal method. The as-prepared MoS2 nanosheets with a high surface area of 106.989 m2 g−1 exhibited excellent wastewater treatment performance with high removal capacities toward organic dyes. In addition, the fungus-like MoS2 nanosheets can absorb Congo red completely within 2 min. Successful access to high quality fungus-like MoS2 nanosheets will make it possible for their potential application in catalysis and other fields.

This paper introduced the preparation, structural, and friction characteristics of graphite-like carbon nitride (g-C3N4)/poly(vinylidene difluoride) (PVDF) composites. The g-C3N4/PVDF composites with different g-C3N4 contents were prepared via wet mixing and hot press molding technique. The structure, morphology, thermal properties, and friction characteristics were studied by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), thermo-gravimetric analysis (TGA), and universal micro-tribotester under dry sliding conditions. The XRD and FT-IR studies confirmed the incorporation of g-C3N4 into the PVDF matrix. The SEM results showed good dispersion of g-C3N4 in PVDF matrix. The “onset” temperature To of the composites increased with increasing the content of g-C3N4 filler, which confirmed the enhancement of thermal stability of the composites. The friction characteristics results indicated that small amount of g-C3N4 filler was not beneficial to reduce friction coefficient of the composite while large amount of filler had little effect on it. In addition, the g-C3N4 filler was beneficial to reduce wear loss of the composite, and the wear loss decreased with increasing the content of g-C3N4 filler.

TiO2 hollow microspheres were successfully synthesized via a controlled hydrolysis reaction, which involved the deposition of an inorganic coating of TiO2 on the surface of carbon spheres and subsequent removal of carbon spheres by calcination in air. The as-prepared TiO2 hollow microspheres with an average diameter of 200 nm presented a novel morphology, which was constructed by closely crosslinked TiO2 nanochains. The morphology of the hollow sphere can be controlled by varying the concentration of TiCl3 solution. A possible formation mechanism was also proposed. The photo-degradation of rhodamine B (RhB) aqueous solution showed that TiO2 hollow microspheres exhibited higher photocatalytic activity than that of TiO2 nanoparticles. The enhanced photocatalytic activity of the as-prepared TiO2 microspheres here could result from their hollow structures assembled by TiO2 nanochains and large light-harvesting efficiency.

To develop novel interface materials for oil/water separation, we describe a simple method to fabricate polyelectrolyte-fluorosurfactant complex-based meshes with superhydrophilicity and superoleophobicity both in air and underwater. The micro/nano-textured surface morphology, along with the interaction of hydrophilic groups and fluorinated alkyl chains, results in simultaneous superhydrophilicity and superoleophobicity. A water droplet can spread over the mesh surface with the contact angle of 0°, while a hexadecane droplet can roll off the mesh easily both in air and underwater. During oil/water separation process, water passed quickly through the mesh by the driving force of gravity and oils were retained above the mesh. As a result, various oil/water mixtures were separated using the mesh with the efficiency above 99.0%. Moreover, the performance stability of the prepared mesh was investigated using air plasma and corrosive aqueous solutions. After treatment, the mesh can keep the superhydrophilicity, superoleophobicity, and high oil/water separation efficiency. Therefore, this superhydrophilic and superoleophobic mesh would be a good candidate for oil/water separation to meet emerging needs in practical applications.

The polyimide (PI)/graphene oxide (GO) nanocomposite films were synthesized by situ polymerization and their tribological behaviors under dry friction, pure water lubrication and seawater lubrication were comparatively investigated. The results showed that PI/GO exhibited better tribological properties under seawater-lubricated condition than other conditions because of excellent lubricating effect of seawater. Besides, the wear resistance of PI had been greatly improved by filling GO under seawater lubrication and reached the top when the content of GO was 0.5 wt%, because strong interfacial adhesion between PI matrix and GO nanofillers could transfer load effectively between the contact surfaces.

Porous and flexible actuating materials are important in the development of smart systems. We report here a facile method to prepare scalable, flexible actuating porous membranes based on a poly(ionic liquid)-modified tissue paper. The targeted membrane property profile was based on a synergy of a gradient porous structure of poly(ionic liquid) network and the flexibility of tissue paper. The gradient porous structure was built up through ammonia-triggered electrostatic complexation of a poly(ionic liquid) with poly(acrylic acid) (PAA) that were previously impregnated inside the tissue paper. As a result, these porous membranes undergo bending deformation in response to organic solvents in vapor or liquid phase and can recover their shape back in air, which was demonstrated to be able to serve as solvent sensors. Besides, they show enhanced mechanical properties due to the introduction of mechanically flexible tissue paper that allows the membranes to be designed as new responsive textiles and contractile actuators., 37 pages, 28 figures

Novel α-Fe2O3 dodecahedron nanocrystals were prepared by a facile one-step hydrothermal method without using any templates. The samples were analyzed by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, respectively. The results revealed that the as-prepared nanocrystals with the average diameters of 200 nm are well-shaped symmetric hexagonal bipyramidal structure. The homogeneous dodecahedron nanoparticles were obtained by optimizing the experimental conditions including reaction temperatures and time. A possible formation mechanism was also proposed. To demonstrate potential applications, the photocatalytic activity of the as-prepared samples was evaluated by photo-degradation of rhodamine B from aqueous solution at room temperature. Results show that the α-Fe2O3 dodecahedron with exposed (012) plane exhibits significantly improved photocatalytic activities for degradation of rhodamine B in aqueous solution under visible light irradiation.

Flower-like TiO 2 nanostructures were successfully synthesized via the urea homogeneous precipitation method using (NH 4 ) 2 TiF 6 as a titanium source in aqueous solution. This approach was simple, environmentally friendly and without using template. The flower-like TiO 2 nanostructures were characterized in detail with scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV–vis spectrum, respectively. The flower-like TiO 2 nanostructures, with diameters ranging from 150–300 nm, were assembled by primary nanoparticles and the length of the petals was approximately 60 nm. Interestingly, the surface of the flower-like TiO 2 nanostructures appeared to have many pores with diameters of 10–13 nm after the sample being calcined at 550 °C, while the morphologies and sizes of the TiO 2 samples did not change. The photocatalytic activity of the as-prepared samples was evaluated by photo-degradation of rhodamine B (RhB) from aqueous solution at ambient temperature. The flower-like porous TiO 2 samples exhibited much higher photocatalytic activity than the flower-like TiO 2 samples. All these advantages showed a bright future for this flower-like porous photocatalyst in environmental protection.

A nanocomposite of graphene oxide (GO) and β-ferric oxyhydroxide (β-FeOOH) nanowire bundles is synthesized by in situ hydrolysis of the precursor ferric chloride and GO nanosheets. Characterization by X-ray diffraction, transmission electron microscopy, and thermogravimetric analysis established the composite structure of the synthesized sample. The results revealed that the surface of GO nanosheets was uniformly assembled by numerous nanowire bundles with diameters in the range of 30–50 nm and lengths of 100–150 nm. Furthermore, β-FeOOH/GO nanocomposites showed a very high adsorption capacity of Congo red and thus these nanocomposites can be used as good adsorbents and can be used for the removal of organic dye from the waste water system.

To overcome easy oil fouling and poor efficiency of traditional oil/water separation materials, superhydrophilic and superoleophobic coatings were fabricated by spray casting chitosan (CTS)-based nanocomposites. The molecular rearrangement of hydrophilic and oleophobic constituents, combined with the hierarchical rough surface structures, enabled a coating with a water contact angle of 0° and a hexadecane contact angle of 157° ± 1°. Hexadecane droplets can easily slide off the dried and water-wetted coating without leaving any obvious oily trailing stains. When the superhydrophilic and superoleophobic CTS-based nanocomposite coatings were applied to oil/water separation, they exhibited excellent anti-fouling capacity, high separation efficiency and easy recyclability. The superhydrophilic and superoleophobic CTS-based coating would be a good candidate for the treatment of industrial oil-polluted water and the cleanup of oil spills.

In this work, we developed a facile and effective hydrothermal method synthesis of MoSe2 nanoflowers on reduced graphene oxide (RGO) sheets. The as-prepared MoSe2/reduced graphene oxide (MoSe2/RGO) composites are characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results indicated that MoSe2 nanoflowers were successfully deposited on RGO nanosheets to form a well interconnected hybrid structure. The tribological properties of MoSe2/RGO composites as lubricating oil additive were investigated by a UMT-2 ball-on-plate friction and wear tester. By the addition of MoSe2/RGO composites in paraffin oil, the antiwear ability was improved and the friction coefficient was decreased. The based oil with MoSe2/RGO composites showed better tribological properties than the oil with MoSe2 and pure oil. The good friction and wear properties of MoSe2/RGO composites as additives were attributed to the formation of a thin physical tribofilm on the substrate.

The magnetic carbon@Fe3O4 nanoparticles have been fabricated by a simple one-step hydrothermal method and applied as adsorbents for removal of organic dyes such as Congo red from aqueous solution. The prepared products were characterized by transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectra, thermo-gravimetric analysis, nitrogen adsorption–desorption isotherms, UV–vis spectrum, and vibrating sample magnetometer. The adsorption performances of the products were tested with removal of Congo red from aqueous solution. The carbon@Fe3O4 nanoparticles possess high adsorption capacity and excellent magnetic separability by an external magnetic field, which is attributed to its high specific surface area providing more surface active sites.

Superoleophobic surfaces with controllable liquid adhesion were developed on micro/nanostructured aluminum substrates through the deposition of polyelectrolyte multilayer films ion-paired with perfluorooctanoate anions. Various liquids, such as water, glycerol, rapeseed oil, and hexadecane, can be tuned from rolling state to pinned state on the superoleophobic surfaces with increasing number of polyelectrolyte bilayers. The effects of chemical heterogeneity and topographic roughness of polyelectrolyte deposited substrates on liquid adhesion properties were systematically studied. The combined effect of surface chemical defects coupled with the disappearance of nanoflakes and the interconnection of protrusions with the polyelectrolyte deposition led to the surfaces changing from sliding superoleophobicity to sticky superoleophobicity. Our results gave a useful attempt to understand the fabrication principle of preparing superoleophobic surfaces with controllable liquid adhesion. Moreover, the function of controllable liquid adhesion from polyelectrolyte multilayer film could potentially be used in important applications, such as in the selection and transportation of microdroplets.

Increasing demands of multi-functional lubricant materials with well distributed nanoparticles has been generated in the field of oil lubrication. In this study, one-dimensional (1-D) acidified multi-walled carbon nanotubes (CNTs) and two-dimensional (2-D) graphene oxide (GO) sheets were dispersed together under an ultra-sonication condition to form CNTs/GO hybrids and the corresponding CNTs/GO hybrids decorated with uniform zero-dimensional (0-D) cerium oxide (CeO2) nanoparticles were prepared via a facile hydrothermal method. The tribological performance of CeO2/CNTs/GO ternary nanocomposite was systematically investigated using a MS-T3000 ball-on-disk tester. The results demonstrated that CeO2/GO/CNTs nanocomposites can effectively reduce the friction of sliding pairs in paraffin oil. Moreover, the oil with 1 wt% of CeO2/GO/CNTs exhibited the best lubrication properties with the lowest friction coefficient and wear scar diameters (WSD) compared with adding only GO nanosheet, CeO2, and CeO2/CNTs hybrid nanocomposite as lubricant additives. It is concluded that due to the synergistic effect of 0D CeO2, 1D CNTs, and 2D GO during sliding process, a dimensionally mixed CeO2/GO/CNTs nanocomposite exhibits excellent lubricating properties, providing innovative and effective additives for application in the field of lubrication.

A facile hydrothermal method has been developed to be capable of decorating graphene oxide (GO) with flower-like TiO2 nanocrystals without using any bridging species. The flower-like TiO2 nanocrystals were uniformly self-assembled on the surface of GO nanosheets. The photocatalytic activity experiment indicated that the prepared TiO2/GO nanocomposites exhibited a higher photocatalytic activity for the photocatalytic degradation of rhodamine B (RB) aqueous solution under the UV illumination, this methodology made the synthesis of TiO2/GO nanocomposites possible and may be further extended to prepare more complicated nanocomposites based on GO for technological applications.

The purpose of this paper was to investigate the tribological properties of carbon materials with various morphologies [i.e., graphene oxide (GO) and carbon spheres (CSs)] utilized as lubricating additives on a ball–plate tribotester. The morphology and spectroscopy characterization of GO and CSs were investigated by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectrometry, and thermogravimetric analysis. Friction and wear properties of the sunflower seed oil filled with GO and CSs were investigated by using a MS-T3000 ball-on-disk apparatus. Results show that the sunflower seed oil containing 0.3 wt% GO nanosheets exhibited a substantial diminution in friction and wear compared with the 3.0 wt% CSs as sunflower seed oil additives. Formation of low-shear strength tribofilms containing GO and its self-lubricating behavior was the key factor in reduction of the friction and prevention from wear and deformation. In addition, friction mechanism of CSs was also discussed.

A commercially available membrane filter paper composed of mixed cellulose esters bearing typically an interconnected pore structure was transformed into a stimuli-responsive bilayer actuator by depositing a thin film of poly(ionic liquid)-modified graphene oxide sheets (GO-PIL) onto the filter paper. In acetone vapor, the as-synthesized bilayer actuator bent readily into multiple loops at a fast speed with the GO-PIL top film inwards. Upon pulling back into air the actuator recovered their original shape. The asymmetric swelling of the top GO-PIL film and the bottom porous filter paper towards organic vapor offers a favorably synergetic function to drive the actuation. The PIL polymer chains in the hybrid film were proven crucial to enhance the adhesion strength between the GO sheets and the adjacent filter paper to avoid interfacial delamination and thus improve force transfer. The overall construction allows a prolonged lifetime of the bilayer actuator under constant operation, especially when compared to that of the GO/filter paper bilayer actuator without PIL., 23 pages, 7 figures

The tribological behavior of poly(ether ether ketone) (PEEK) composites was investigated using a universal micro-tribotester under dry friction conditions. We studied the effect of addition concentration, applied load, and sliding speed on the friction and wear behavior of composites filled with multi-walled carbon nanotubes (MWNTs), graphene oxide (GO) nanosheets, and γ-aminopropyl trimethoxysilane-modified graphene oxide (GO-Si) nanosheets. The results showed that the friction reduction and anti-wear performance of PEEK composites filled with GO-Si is the most effective, that of the composites filled with GO is the next, while that of the composites filled with MWNTs is the worst. GO-Si-filled PEEK nanocomposites have the best friction reduction and anti-wear properties when the applied load and the sliding speed are 2.94 N and 0.0628 ms−1, respectively. Furthermore, scanning electron microscope (SEM) investigation showed that GO-Si-filled PEEK composites had smooth worn surface under given applied load and sliding speed, and well-dispersed GO-Si in PEEK matrix provided a large surface area available for interaction between polymer molecules and GO-Si, which helped to reduce the wear of PEEK composites.