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The operating voltage for supercapacitors (SCs) in alkaline electrolyte was limited by the splitting of water. Therefore, it is still a huge challenge to obtain high energy density by improving the operating voltage for aqueous symmetric SCs. Herein, a novel strategy is developed to construct the 3D boron/nitrogen dual doped layered carbon (BNLC) by using the in-situ potassium tetraborate activation from biomass. The synergetic effects of B/N heteroatoms and 3D layered structures enhance the electron transport property, and achieve the high voltage window of 2 V for SCs in 3 M Zn(CF3SO3)2 aqueous electrolyte. As a result, the BNLC presents high specific capacitance of 315.3 F g−1 at 0.05 A g−1, good rate performance of 241.1 F g−1 at 40 A g−1 and excellent cycle stability with 98.4% of initial capacitance after 20,000 cycles. In addition, the energy density of BNLC-based SC in neutral electrolyte (43.8 Wh kg−1) is 4.4 times as high as that of BNLC-based SC in alkaline electrolyte (9.9 Wh kg−1). This work pioneers an efficient strategy for the use of the synergetic effects of heteroatoms and neutral electrolyte to enhance the energy density of energy storage devices.

A 3D printed conformal polarization converter, based on a novel dielectric unit cell, is proposed for linear-to-circular polarization conversion. The designed dielectric unit cell comprises a cuboid-shaped dielectric block and a thin square dielectric substrate layer for ease of fabrication with 3D printing technology. Meanwhile, the unit cell can achieve linear-to-circular polarization conversion performance from 14.2 GHz to 20.1 GHz with 3-dB axial ratios (ARs) of 34% and good angular stability within 40°. Then, the unit cell is applied to design the conformal dielectric linear-to-circular polarization converters (LCPCs) for cylindrical and spherical surfaces, respectively. To verify the feasibility, three kinds of dielectric converters including planar, cylindrical, and spherical shapes are fabricated and measured. The measured results demonstrate that the proposed dielectric polarization converters with different shapes can produce almost similar linear-to-circular polarization performances with low loss, high conversion efficiency, and angular stability within 40°.

Bone defect repairs are based on bone graft fusion or replacement. Current large bone defect treatments are inadequate and lack of reliable technology. Therefore, we aimed to investigate a simple technique using three-dimensional (3D)-printed individualized porous implants without any bone grafts, osteoinductive agents, or surface biofunctionalization to treat large bone defects, and systematically study its long-term therapeutic effects and osseointegration characteristics. Twenty-six patients with large bone defects caused by tumor, infection, or trauma received treatment with individualized porous implants; among them, three typical cases underwent a detailed study. Additionally, a large segmental femur defect sheep model was used to study the osseointegration characteristics. Immediate and long-term biomechanical stability was achieved, and the animal study revealed that the bone grew into the pores with gradual remodeling, resulting in a long-term mechanically stable implant-bone complex. Advantages of 3D-printed microporous implants for the repair of bone defects included 1) that the stabilization devices were immediately designed and constructed to achieve early postoperative mobility, and 2) that osseointegration between the host bone and implants was achieved without bone grafting. Our osseointegration method, in which the “implant-bone” interface fusion concept was used instead of “bone-bone” fusion, subverts the traditional idea of osseointegration., Graphical abstract Image 1, Highlights • A new “implant-bone” interface fusion concept for large bone defect treatment was realized using 3D-printed porous implants. • Osseointegration was achieved without bone grafting. • An animal study revealed that the bone grew into the pores with gradual remodeling. • Immediate and long-term biomechanical stability was achieved by this method.

Aiming at the refined microstructure and enhanced thermal conductivity of high-entropy carbide (HEC) ceramics for high-temperature applications, the addition effect of graphite was comprehensively investigated in this study. HEC ceramics incorporated with different contents of graphite were solidified by spark plasma sintering (SPS) using self-synthesized high-entropy (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)C powder and graphite as starting materials. The results demonstrate that the incorporated graphite removed the oxygen impurity in the mixed powders, decreased the oxygen content and increased the lattice parameter of the HEC phase, and improved the densification behavior of HEC ceramics. On the other hand, the addition of graphite brings a refinement of HEC grains and improves the mechanical properties. More importantly, the thermal conductivity of the HEC ceramics was significantly increased owing to the removing effect of oxide impurity by the added graphite. It is considered that the lattice "purified" HEC grains with low oxygen content contribute to the improvement in thermal conductivity of the ceramics.

In this letter, a novel elliptical cylinder dielectric resonator (ECDR) is proposed. By combining a square substrate and two symmetrical ECDRs, an ECDR element is formed, which can effectively achieve the transformation from the linearly polarized incident wave to the circularly polarized (CP) transmitted wave. By adjusting the height of the element, a linear transmission phase range over 360° can be obtained, which can reduce the fabrication difficulty and cost through a 3-D printed technology significantly. Meanwhile, the ECDR element has a low conductor loss in high frequency. Additionally, a CP 3-D printed dielectric transmitarray antenna at the millimeter-wave band is designed by employing the ECDR elements. It is found that the aperture efficiency is up to 40.3%, the 3 dB axial ratio bandwidth is 17%, and the 1 dB gain bandwidth is 13.3%, respectively. The measured results are in good agreement with the simulated ones. This may be the first time that a CP 3-D printed dielectric transmitarray antenna has been reported.

An extremely facile and up-scalable approach has been proposed to disperse ferric grains onto bacterial cellulose (BC) nanofibers. The BC-induced hydrolytic deposition can be performed at room temperature without using any organic solvents, toxic reagents, or complicated apparatuses, enabling a green pathway in realizing industrialization. After carbonization, the randomly oriented carbonized BC (CBC) nanofibers transmit the electrons throughout the electrode, while the inherited reticular morphology boosts the thorough penetration of electrolyte. Moreover, the sufficient space created by interconnected CBC nanofibers is able to accommodate the volume change of the nanosized Fe3O4 active materials during repeated Li+ intercalation and deintercalation. As a result, the as-prepared Fe3O4/CBC composites deliver the superior electrochemical performance as the free-standing anodes in Li-ion batteries (LIBs), including the impressive reversible capacity of 702 mAh g−1 after 400 cycles at 400 mA g−1, decent rate capability with capacity of 437 mAh g−1 at 2000 mA g−1, and a long cycling lifespan up to 1000 cycles at 800 mA g−1. This work provides a scalable and green approach to fabricate high-performance LIBs anode with the natural sustainable biomass.

By making use of first principles calculations, lithium-decorated (Li-decorated) and nitrogen-doped (N-doped) penta-graphene (PG) was investigated as a potential material for hydrogen storage. The geometric and electronic structures of two types of N-doped PG were studied, and the band gaps were 1.86 eV and 2.06 eV, respectively, depending on the positions of the substitution. The probable adsorption sites for Li atoms on topside and downside were calculated. Hydrogen molecules were added one by one to Li-decorated N-doped PG to research the maximum hydrogen gravimetric density. It is found that up to 5 hydrogen molecules on topside and 8 hydrogen molecules on downside can be adsorbed around a Li atom, and the average adsorption energies are in the range of physical adsorption processes (0.1–0.4 eV). The gravimetric densities can reach 7.88 wt% for N-doped PG with Li decoration. Our results suggest that Li-decorated N-doped PG is a significantly promising material for hydrogen storage.

A charge‐trapping memory (CTM) field effect transistor (FET) featured with an Hf1.5Gd2O6 charge trapping layer and thin MoS2 channel are fabricated. Benefit from high defect densities of the Hf1.5Gd2O6 film, large memory windows are achieved under low operating voltages (2.3 V@4 V, 3.1 V@5 V and 3.6 V@6 V), which distinctly outperform previously reported CTMs. In addition, high programming/erase (P/E) speeds, good data retention and endurance characteristics are experimentally demonstrated. The results demonstrate a feasibility of CTM FET with an HfGdO charge trapping layer and thin MoS2 channel for ultra‐low power memory devices application.

Black titanium dioxide (TiO2‐x) has attracted extensive attention owing to its visible light absorption and superior photodegradation activity. Here, black TiO2‐x nanocomposites are fabricated via a two‐step method followed by a heat treatment process under an argon atmosphere, and then the black TiO2‐x is loaded onto the bacterial cellulose surface by surface grafting. The presence of Ti3+ species and oxygen vacancies is proved by XPS characterisation. Furthermore, the black TiO2‐x exhibits excellent photocatalytic activity for pollutants degradation.

As a kind of rare materials, nano-silver has broad application prospects in the fields of catalysis, medical treatment, new energy and so on. However, there are few reports on the systematic research of nano-silver in ceramic glazes. In this work, different color ceramic glazes were produced by tuning the nano-silver content and optimizing the firing process. The crystalline phase composition, micro-morphology and elemental distribution of fired glazes were analyzed and discussed in depth. The elemental composition and distribution of the samples were studied. The surface of the glazes with varying Ag contents fired under the reducing atmosphere exhibited blue-white. And the blue color is attributable to Rayleigh scattering that may arise because the phase-separation structures existed in glazes. Interestingly, the color of the ceramic glazes with varying Ag contents changed to golden-yellow when the ceramic glazes were fired under the air atmosphere. Golden-yellow color of the samples fired under the air atmosphere is mainly attributable to the silver nano-particles, though Ag+ may be existed in the glazes.

A broadband folded reflectarray antenna (FRA) is presented employing a novel single-layer cross-polarization conversion (CPC) subwavelength element in this letter. The proposed element has a very simple structure and consists of only a square ring resonator loaded with two splits, thereby realizing easy fabrication with low cost. By varying the length of the ring and mirroring the element, a 360° phase change range is achieved with low losses at the center frequency. These characteristics make the proposed configuration unique, as most of the reported FRA elements rely on complex and multilayer structures to realize the broadband CPC. Furthermore, an FRA using the proposed elements is designed and measured at 22 GHz. A good agreement between the simulated and measured results is obtained. The measured results demonstrate that the proposed FRA realizes a 1 dB gain bandwidth of 20.9% and a maximum aperture efficiency of 47.8%.

Nowadays, multi-shelled mesoporous hollow metal oxide nanospheres have drawn a lot of attention due to their large internal space, nanometer scaled shell thickness, high specific surface area and well-defined mesopores, of which unique nanostructure endows metallic oxides with enhanced properties. In this thesis, we have studied and proposed a versatile ligand-assisted cooperative template method to synthesize multi-shelled mesoporous hollow metal hydroxides and oxides nanospheres, in which silica nanospheres act as sacrificial templates and the coordination interaction between metal ions and surfactant can be cooperatively amplified by using chelating ligand (ascorbic acid) as a co-template. The synthesized metal hydroxides and oxides nanospheres possess stable hollow structure, uniform spherical morphology and tunable diameter from 270 to 690 nm. All the multi-shelled mesoporous hollow metal hydroxide and metal oxide nanospheres exhibit high surface areas (up to 640 m2/g). The obtained Au nanoparticles loaded composited nanospheres exhibit excellent reactivity for solvent-free aerobic oxidation of ethylbenzene with high activity (28.2%) and selectivity (87%).

An efficient strategy that can guide the synthesis of materials with superior mechanical properties is important for advanced material/device design. Here, we report a feasible way to enhance hardness in transition-metal monocarbides (TMCs) by optimally filling the bonding orbitals of valence electrons. We demonstrate that the intrinsic hardness of the NaCl- and WC-type TMCs maximizes at valence electron concentrations of about 9 and 10.25 electrons per cell, respectively; any deviation from such optimal values will reduce the hardness. Using the spark plasma sintering technique, a number of W1-xRexC (x = 0-0.5) have been successfully synthesized, and powder X-ray diffractions show that they adopt the hexagonal WC-type structure. Subsequent nanoindentation and Vickers hardness measurements corroborate that the newly developed W1-xRexC samples (x = 0.1-0.3) are much harder than their parent phase (i.e., WC), marking them as the hardest TMCs for practical applications. Furthermore, the hardness enhancement can be well rationalized by the balanced occupancy of bonding and antibonding states. Our findings not only elucidate the unique hardening mechanism in a large class of TMCs but also offer a guide for the design of other hard and superhard compounds such as borides and nitrides.

Al−high Si alloys were designed by the addition of Cu or Mg alloying elements to improve the mechanical properties. It is found that the addition of 1 wt.% Cu or 1 wt.% Mg as strengthening elements significantly improves the tensile strength by 27.2% and 24.5%, respectively. This phenomenon is attributed to the formation of uniformly dispersed fine particles (Al2Cu and Mg2Si secondary phases) in the Al matrix during hot press sintering of the rapidly solidified (gas atomization) powder. The thermal conductivity of the Al−50Si alloys is reduced with the addition of Cu or Mg, by only 7.3% and 6.8%, respectively. Therefore, the strength of the Al−50Si alloys is enhanced while maintaining their excellent thermo-physical properties by adding 1% Cu(Mg).

Zirconium carbide (ZrC) ceramics is an important candidate material for structural applications both at high temperature and intensive irradiation. However, its sensitivity to defects and cracks often causes low reliability and limited the application of ZrC ceramics. In this work, graphite nanoplatelets (GNPs) doped zirconium carbide ceramics were prepared by spark plasma sintering (SPS). The results show that the addition of GNPs not only improved the densification of ZrC ceramics but also inhibited grain growth of ZrC matrix phase. The GNPs were mainly located at the grain boundaries, and the c-axis of the disk-like GNPs preferred to align with the applied pressing direction during SPS. The preferred orientation of GNPs in the sintered ceramics resulted in anisotropic microstructure and fracture toughness of the material. Compared with the monolithic ZrC ceramics with a fracture toughness of 2.27 MPa m1/2, GNPs doped ceramics shows higher fracture toughness. The fracture toughness of ZrC ceramics with 0.5, 1.5, 3 vol% GNPs are 2.70 MPa m1/2, 3.03 MPa m1/2 and 3.24 MPa m1/2 measured on the surface perpendicular to the applied pressing direction and 3.43 MPa m1/2, 3.66 MPa m1/2 and 4.55 MPa m1/2 measured on the surface parallel to the applied pressing direction, respectively. The crack deflection and re-initiation by GNPs are the main toughening mechanisms for the GNPs doped ZrC ceramics.

Brazing diamond tools were used to machining monocrystal sapphire dome. The effects of processing parameters on the cutting force, surface quality were researched. The results showed that the speed...

Zn2Ti3O8/g-C3N4 (0, 1, 3 and 8 wt%) composites were prepared via a simple solvothermal method, and their physical and electrochemical properties were systematically analyzed. SEM and HRTEM results show that the Zn2Ti3O8/g-C3N4 spherical structures with width sizes of about 500–700 nm are plump and uniform. Moreover, g-C3N4 with a large specific surface area can effectively buffer the deformation of Zn2Ti3O8 and reduce the resistance of Zn2Ti3O8 charge transfer and Li+ diffusion, thus improving the conductivity of Zn2Ti3O8. The results reveal that Zn2Ti3O8/g-C3N4 (3 wt%) had the most outstanding electrochemical performance of all samples. It can deliver discharge (charge) capacities of 444.6 (387.9), 284.5 (280.8), 197.5 (199.9), 149.9 (149.3), 119.2 (118.7) and 81.4 (81) mA h g−1 cycled at 50, 100, 300, 600, 900, and 1500 mA g−1, respectively. At the same current densities, pure Zn2Ti3O8 only provides discharge (charge) capacities of 325.4 (283.5), 223.7 (219.5), 142.9 (141.8), 95.4(94.8), 69.4 (69.4) and 38.3 (39.3) mA h g−1. The results verify that Zn2Ti3O8/g-C3N4 materials are expected to be remarkable anode materials for Li-ion batteries.

Temperature is a critical parameter for evaluating battery safety during the process of charging and discharging. However, it is a challenge to monitor it accurately because batteries are used in various compact environments such as energy stations. In this study, β-NaYF4:Er3+/Yb3+@NaYF4 nanoparticles were used to fabricate an optical fiber temperature sensor for battery temperature monitoring. The temperature sensing characteristics of the optical fiber sensor were explored in the range of 293–373 K using fluorescence intensity ratio (FIR) technology which can improve the temperature monitoring accuracy. The maximum relative sensitivity of the optical fiber sensor was 1.62% K−1 at 293 K and the temperature detection limit was within ±0.5 °C. By embedding the prepared sensor in a Li-ion battery, the proof of concept was obtained for monitoring the internal temperature of a battery with upconversion nanoparticles (UCNPs). A larger temperature variation was observed under a higher discharge rate. These results indicate that the prepared optical fiber sensor is an active tool for monitoring the thermal behavior and improving the safety of the battery.

Two balanced microstrip dual-band bandpass filters (BPFs) based on short stub loaded resonator (SSLR) and open stub loaded resonator (OSLR) are presented in this brief, respectively. The center frequencies of the two differential-mode (DM) passbands can be controlled quasi-independently by adjusting the lengths of resonators. Moreover, a stepped impedance microstrip line etched with an interdigital coupling line is utilized to introduce a coupling between the two resonators, which generates two extra controlled transmission zeros (TZs) to obtain better selectivities. Furthermore, balanced microstrip/ slotline (MS) transition structures are employed as feed networks, which can suppress common-mode (CM) inherently while the DM responses are not affected, thereby the design procedure can be simplified significantly. In order to demonstrate the theoretical design, two balanced dual-band BPFs were designed and fabricated. The simulated responses are compared with the measured ones and a good agreement is obtained.

Despite the widely explored biomaterial scaffolds in vascular tissue engineering applications lately, no ideal platform has been provided for small diameter synthetic vascular grafts mainly due to the thrombosis issue. Endothelium is the only known completely non-thrombogenic material; so, functional endothelialization onto vascular biomaterials is critical in maintaining the patency of vascular networks. Bacterial cellulose (BC) is a natural biomaterial with superior biocompatibility and appropriate hydrophilicity as potential vascular grafts. In previous studies, surface modification of active peptides such as Arg-Gly-Asp (RGD) sequences onto biomaterials has been proven to achieve accelerated and selective endothelial cell (EC) adhesion. In our study, we demonstrated a new strategy to remotely regulate the adhesion of endothelial cells based on an oscillating magnetic field and achieve successful endothelialization on the modified BC membranes. In details, we synthesized bacterial cellulose (BC), magnetic BC (MBC), and RGD peptide-grafted magnetic BC (RMBC), modified with the HOOC-PEG-COOH-coated iron oxide nanoparticles (PEG-IONs). The endothelial cells were cultured on the three materials under different frequencies of an oscillating magnetic field, including "stationary" (0 Hz), "slow" (0.1 Hz), and "fast" (2 Hz) groups. Compared to BC and MBC membranes, the cells on RMBC membranes generally show better adhesion and proliferation. Meanwhile, the "slow" frequency of a magnetic field promotes this phenomenon on RMBC and achieves endothelialization after culture for 4 days, whereas "fast" inhibits the cellular attachment. Overall, we demonstrate a non-invasive and convenient method to regulate the endothelialization process, with promising applications in vascular tissue engineering.

This research aimed to expand the nanomaterial-based drug loading method for the recombinant tissue plasminogen activator (rtPA) treatment of acute phase thrombolysis in ischemic stroke. In this research, the coprecipitation method was used to prepare Fe3O4 magnetic nanomaterials. Polyacrylic acid (PAA) was coated on the surface of the nanomaterials. The nanomaterials were subjected to hydroxyl activation treatment so that it could be connected to rtPA. By EDC/NHSS method, rtPA was covalently attached to the surface of nanomaterials to form a composite nanomaterial that was modified by rtPA, which was FPA-rtPA. Firstly, the material was characterized, then the pharmacokinetics of the material was evaluated. Finally, the thrombus targeting and thrombolytic properties of the material were analyzed. In the experiment, Fe3O4, FPA, PAA, and FPA-PAA were monitored by FT-IR, the peak value of PAA at 1834 cm–1 meant C=O group, and PAA-FPA had a similar peak, each milligram of nanomaterial can be combined with 80.6 μg ± 1.4 μg of rtPA. In the pharmacokinetic test, the half-life of FPA-rtPA was 90 min, which was much higher than the half-life of rtPA in the free state (P < 0.001), so it was suitable as a targeted thrombolytic preparation; the fluorescence intensity of the FPA-rtPA group combined with the fibrin blood clot was significantly stronger than the FPA group, and rtPA-FPA can target fibrin thrombosis in the cerebral thrombosis model. After comparing the postoperative cerebral infarction area, the rtPA-FPA-based group of rats had a significant decrease in cerebral infarction area (P < 0.001), thus the nanomaterials had better thrombolytic properties.

In this work, WO3 films were synthesized by glancing angle deposition (GLAD) and conventional planar deposition respectively. By depositing Pt on WO3 by GLAD, the NO2 sensitivity of WO3 films were significantly improved. The structural characteristics and NO2 sensing properties of the films were investigated in order to establish the enhancement mechanism. The results show WO3 films prepared by GLAD have porous nanorod-like structure, and isolated Pt clusters are distributed on WO3. The nanostructured Pt/WO3 films show high sensitivity to NO2 at 150 °C, detecting as low as 80 ppb NO2 with a response of 1.23. Meanwhile, the films also exhibit high NO2 selectivity against NH3, CO, acetone and ethanol. The excellent NO2 sensing properties of the Pt/WO3 films can be explained due to large specific surface area of nanorod-like WO3, catalysis of Pt and Schottky barriers at interfaces. The reliable Pt/WO3 nanostructure prepared by GLAD could be potentially applied in low-temperature, highly sensitive NO2 sensor for micro-electro-mechanical system (MEMS).

A homogeneous porous Co3O4-ZnO nanomaterial (Zn-CoOx) was successfully fabricated by precipitation-annealing route. The as-prepared Zn-CoOx exhibited good response, reliable reversibility and good selectivity towards alcohols, which attributed to the porous structure and p-n heterojunction formed between Co3O4 and ZnO. In particular, the different Fermi levels of Co3O4 and ZnO leaded to a further increase the depth of the space charge layer, which improved the gas sensitivity of the material from 10% to 480%. Besides, the continuous Co3O4 leaded to a relatively lower operating temperature and resistance. This material preparation method and bimetallic oxides could be widely used in the research and development of metal oxide gas sensitive materials and sensors.

We report a success in synthesizing high entropy silicides (HES) compounds and manufacturing well-densified HES ceramics through spark plasma sintering. For a designed chemical formula as (Ti0.2Zr0.2Nb0.2Mo0.2W0.2)Si2, the as-synthesized HES showed a formula as (Ti0.22Zr0.06Nb0.29Mo0.22W0.21)Si2 with zirconium partially oxidized into zirconia. Doping with aluminum resulted in a HES with the same composition, promoted formation of ZrSi2 and Al2O3. XRD analysis of as-synthesized HES is well supported by the calculated diffraction data based on a 2 × 3 × 1 supercell with HCP crystal structure and experimental chemical composition. The cations in this HES crystal structure can occupy their positions randomly with little change of its lattice parameters and formation enthalpy.

High performance flexible pressure sensors have received tremendous attention due to the potential applications in wearable electronics and humanoid robotics. Herein, a low-cost, time-saving fabrication strategy is reported to efficiently construct highly sensitive and scalable pressure sensors based on graphene-textile. The flexible pressure sensor was prepared through a dip coating approach where the graphene ink was used as the active material and textile with ordered network structure, serves as the flexible support matrix. By increasing the number of layers of the textile, the pressure sensor could achieve a high linear sensitivity value of 0.23 kPa−1, a broad pressure range from 0 to 140 kPa, and a durability over 800 cycles. It was found that the network structure of the graphene-textile contributed to the enhancement of the sensing performance due to the piezoresistive effect resulting from the deformation of conductive graphene-textile. Moreover, by virtue of its exceptional properties, it is demonstrate that the high performance flexible pressure sensor could be further used to detect human physiological signals, such as wrist pulse, finger press detection and walking state monitoring, indicating its promising potential to flexible and wearable electronics.

Topological crystalline insulator (TCI) as a new type of topological materials has attracted extensive research interests for its tunable topological properties. Due its symmetry topological protection essence, the structure investigation provides a solid basement for tuning its topological transport properties. On SrTiO3 (111) substrate, the SnTe film was found to be epitaxial growth only along [001] while not [111] direction. The detailed structural study was performed and a structural model was proposed to elucidate epitaxial growth of the SnTe (001) film. The transport properties of SnTe (001) film were further investigated and a typical weak anti-localization effect was observed. By Pb-doping into SnTe, the bulk carriers were inhibited and its topological surface states were strengthened to induce the enhanced surface transport contribution. With tunable multiple transport channels from the even Dirac cones, the TCI SnTe film systems will have the potential application in future spintronics devices.

The relationships between microstructures and mechanical properties especially strength and toughness of high-entropy carbide based ceramics are reported in this article. Dense (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)C (HEC) and its composite containing 20 vol.% SiC (HEC-20SiC) were prepared by spark plasma sintering. The addition of SiC phase enhanced the densification process, resulting in the promotion of the formation of the single-phase high-entropy carbide during sintering. The high-entropy carbide phase demonstrated a fast grain coarsening but SiC particles remarkably inhibited this phenomena. Dense HEC and HEC-20SiC ceramics sintered at 1900 °C exhibits four-point bending strength of 332 ± 24 MPa and 554 ± 73 MPa, and fracture toughness of 4.51 ± 0.61 MPa·m1/2 and 5.24 ± 0.41 MPa·m1/2, respectively. The main toughening mechanism is considered to be crack deflection by the SiC particles.

A recent progress in new emerging two-dimensional (2D) materials has provided promising opportunity for gas sensing in ultra-low detectable concentration. In this work, we have demonstrated a flexible NO2 gas sensor with porous structure graphene on polyethylene terephthalate substrates operating at room temperature. The gas sensor exhibited good performance with response of 1.2% and a fast response time within 30 s after exposure to 50 × 10−9 NO2 gas. As porous structure of graphene increased the surface area, the sensor showed high sensitivity of ppb level for NO2 detection. Au nanoparticles were decorated on the surface of the porous structure graphene skeleton, resulting in an incensement of response compared with pristine graphene. Au nanoparticles-decorated graphene exhibits not only better sensitivity (1.5–1.6 times larger than pristine graphene) for NO2 gas detection, but also fast response. The sensor was found to be robust and sensitive under the cycling bending test, which could also be ascribed to the merits of graphene. This porous structure graphene-based gas sensor is expected to enable a simple and inexpensive flexible gas sensing platform.

High-entropy carbide ceramics (Ti0.2Hf0.2Nb0.2Ta0.2W0.2)C is prepared from five transition metal oxides and graphite by reactive spark plasma sintering. X-ray diffraction indicates the synthesized ceramics with the single-phase face-centered cubic structure. The elemental distribution maps by energy dispersive spectroscopy demonstrate homogeneous distribution of the five metal elements in both central and circumferential regions of the sample. SEM and corresponding back scattered electron observations show the residual graphite particles locating at the grain boundaries of high-entropy carbide ceramics. Moreover, the content of the residual graphite decreases and the grain size of the high-entropy carbide phase increases from central to circumferential region of the sample. Thermodynamic calculation results indicate that gradient gas pressure inside the sample affects the carbothermal reduction reactions during sintering and consequently results in the existence of residual graphite with gradient distribution feature. This study points out an effective way to inhibit the grain growth of high-entropy carbide phase during sintering process by the incorporation of graphite as the second phase particles acting as grain growth inhibitor.

The pulse current oxidation methods were used to degrade the malachite green (MG) using lead dioxide as anodes. The influences of operating parameters, including pulse frequency, pulse curr...

Cleaner production of photocatalyst with efficient property and stable reusability is of great importance for the elimination of organic pollutants in wastewater. Herein, we present a bacterial cellulose (BC)-based nanocomposite membrane with enhanced adsorption and photocatalytic degradation for dyes under UV radiation, by using BC nanofibers as a three-dimensional soft template, coated with the polydoamine (PDA) as a functional layer and a protective agent for immobilization of titanium dioxide (TiO2) nanoparticles. Compared with commercial P25, the as-prepared BC/PDA/TiO2 composite presented higher adsorption capacity for methyl orange, Rhodamine B and methylene blue, and the photocatalytic properties within 30 min after irradiation were further improved. BC/PDA/TiO2 also showed good stability, proved by the 5.5% reduction in photocatalytic capability after five cyclic tests. We expect our design could provide a facile and green approach with excellent photo-degradation performance for organic pollutants, providing further applications for photocatalysis and wastewater treatment.

Inspired by the magical biomimetic structure of mosses grown on rocks, form interconnected networks to enhance the accessible surface to nutrients, we report the synthesis of hybrid porous carbons ...

Many interesting multifunctional materials are obtained under the application of an external electric field, which arouses extensive interest of experimental and theoretical researchers. In the pre...

Purpose This paper aims to improve the corrosion resistance performance and stability of PbO2 electrodes in chloride wastewater. Design/methodology/approach The morphology of PbO2-ZrO2 nanocomposite electrodes was observed by scanning electron microscopy (SEM). The open circuit potential (OCP) curves, anodic polarization curves, electrochemical impedance spectra, accelerated life tests, weight-loss tests and reusability tests were used to study the corrosion resistance properties and stability of PbO2-ZrO2 nanocomposite electrodes in NaCl solution. Findings SEM showed that the surface morphology of PbO2-ZrO2 nanocomposite electrodes became compacted and smooth. Electrochemical tests showed that ZrO2 nanoparticles could increase the OCP, corrosion potential and charge transfer resistance, and decrease the corrosion current density in 3.5 Wt. per cent NaCl electrolyte solution. Besides, PbO2-ZrO2 nanocomposite electrodes showed high reusability for acetamiprid degradation, the accelerated service life could reach 146 h, which was almost 3.3 times longer than that of PbO2 electrodes (44 h), weight-loss tests showed that the corrosion resistance for PbO2-ZrO2 nanocomposite electrodes was 2.3 times as compared to PbO2 electrodes. Originality/value By the codeposition of ZrO2 nanoparticles, the corrosion resistance performance and stability of PbO2 electrodes in NaCl electrolyte were improved.

Hierarchical porous CoFe-LDHs composed of ultrathin nanosheets were successfully prepared by a simple one-step precipitation process of Co2+ and Fe3+ ions, avoiding multiple tedious steps. The optimized composition and the hierarchical porous structure design of the CoFe-LDHs endow them with high activity for OER in alkaline media (1 M KOH). Benefiting from the synergistic catalytic effects of the controllable composition and the structural features of CoFe-LDHs, the superior OER performance of hierarchical porous Co8Fe1-LDH nanosheets with optimal composition is achieved with the smallest overpotential (262 mV at 10 mA cm−2), lowest Tafel slope (42 mV per decade), and excellent long-term stability, which is superior to previously reported LDH-derived and commercial iridium dioxide (IrO2) electrocatalysts, suggesting its promising application as an efficient electrode for OER.

Co3O4 is a promising p-type semiconductor for ethanol detection. In this work, ethanol detection sensors were fabricated with nanostructured Co3O4, which exhibited higher selectivity and lower operating temperature. The Co3O4 was synthesised using ZIF-67 as a sacrificial precursor. The T400-Co3O4 that was obtained by calcining ZIF-67 at 400 °C showed the best sensing performance. Its response to 100 ppm ethanol vapor was 221.99 at a low optimal operating temperature (200 °C). Moreover, T400-Co3O4 achieved a low detection limit (1 ppm), remarkable repeatability, and higher selectivity compared to ammonia, carbon monoxide, acetone, hydrogen, methane, methanol, and nitrogen dioxide. The enhanced sensing performance was mainly attributed to three factors: (1) the adsorption/desorption of active adsorbed oxygen molecules (e.g. O− and O2−) and abundant oxygen vacancies, which increased the number of active sites; (2) the catalytic activity of Co3+, which greatly increased the reaction route and decreased the activation energy; and (3) the effective diffusion of gas molecules, which increased the effect of collisions between gas molecules and the material surface. This work provides an effective means to fabricate sensitive ethanol gas sensors with low energy consumption.

In present work, a comprehensive simulation method coupled with Monte Carlo Ray Tracing (MCRT) method and Finite Volume Method (FVM) is employed to simulate the complex photo-thermal conversion of PDC system. The whole photo-thermal conversion process is divided into two sub-processes, namely PartⅠ receiver walls absorb solar energy as thermal energy, and PartⅡ receiver walls convey thermal energy to heat transfer fluid (HTF) and ambient air. PartⅠ (optical performance) is evaluated by MCRT and the solar flux distribution on walls is obtained. PartⅡ (thermal performance) is solved by FVM model in which the solar flux on walls is treated as a source term. It is shown that the legitimate adjustment of receiver position, rim angle, tilt angle and emissivity will increase photo-thermal conversion efficiency by 2.6%, 2.4%, 8% and 1.8% respectively. Appropriate mass flow rate in this work is chosen as 0.02 kg/s for insuring high outlet temperature with higher photo-thermal efficiency as possible. In addition, photo-thermal conversion efficiency will largely rise up 8% for every 0.1 growing of absorptivity. These results would enrich the literature archive tremendously and be needed for better solar power generation engineering design.

Fabricating electron transport layers at low temperatures is challenging but highly desired in the field of flexible perovskite solar cells (f-PSCs). In this study, highly uniform cerium oxide (CeOx) films prepared by the UV–O3 treatment have been successfully applied as the electron transport layer (ETL) in methylammonium lead halide (CH3NH3PbI3) perovskite-based f-PSCs. Under AM 1.5 G sunlight with 100 mW cm−2, these cells exhibited an open-circuit voltage (Voc) of 0.98 V, a short-circuit current density (Jsc) of 19.42 mA cm−2, a fill factor (FF) of 0.72 and power conversion efficiency (PCE) of 14.63%. The PCE was much higher than that of the control planar CeOx ETL (PCE ∼ 9.08%) prepared at a low temperature (80 °C) without the UV–O3 treatment, and this was ascribed to the improved CeOx film, enhanced light absorption and suppressed charge recombination. The cells that bend at 15 mm of radius showed excellent stability with less than 10% reduction in PCE after 500 cycles of repeated bending at ambient temperature. The charge-transmission kinetic parameters and long-term stability of the CeOx-based f-PSCs were analyzed as well.

Indium oxide (In2O3)-based photocatalysts have great potential in photocatalytic CO2 reduction. Nevertheless, their photocatalytic activity is inhibited by rapid electron–hole recombination. Hence, a novel Z-scheme ternary hierarchical ZnFe2O4/RGO/In2O3 photocatalyst is fabricated for photocatalytic conversion of CO2 to CO and CH4. The CO production rate reaches up to 35.4 μmol g−1 under 4 h of illumination using a 20ZFO/10RGO/IO catalyst, which is 3.9 times and 9.8 times higher than those using bare In2O3 and bare ZnFe2O4, respectively. The CH4 production rate is 7.8 μmol g−1, which is 4.3 fold and 2.4 fold higher, respectively, compared to those from bare In2O3 and bare ZnFe2O4. The enhancement of photocatalytic CO2 reduction was ascribed to a Z-scheme mechanism of the hierarchical catalysts by introducing RGO in-between In2O3 and ZnFe2O4 to promote charge separation and realize efficient utilization of the high-energy electrons and holes. The oxygen-defect of ZnFe2O4 also facilitates the adsorption and activation of CO2. This work provides new insights to design ternary In2O3-based hierarchical photocatalysts with a rational Z-scheme photocatalytic mechanism to improve the CO2 conversion efficiency.

In this study, a performance-enhanced charge trapping memory device with a Pt/Gd-doped HfO2/SiO2/Si structure has been investigated, where Gd-doped HfO2 acts as a charge trapping and blocking layer. The device demonstrates a large memory window of 5.4 V under a ±5 V sweeping voltage (360% of the device with pure HfO2), which is extremely attractive in low-power applications. In addition, the device also exhibits good retention characteristics with a 24.5% charge loss after the retention time of 1 × 105 seconds and robust endurance performance with a 1% degradation after 1 × 104 program/erase cycles. It is considered that the high density of defect states and the reduction in the defect energy levels induced by Gd-doping contribute to the performance improvement.

Solid-state high-power heat output at a relatively low temperature is a core problem for photo thermal batteries (PTB) films because of the fundamental contradiction between fast heat release and low-rate isomerization. To overcome this problem, imidazole-containing azoheteroarene (i-Azo-h) is introduced into a graphene-templated assembly for low-temperature time-resolved heat release. Intramolecular pull-push electronic interaction of i-Azo-h in the assembly film results in high-rate and high-degree trans-cis isomerization compared with azobenzene. The uniform i-Azo-h/graphene PTB film reaches very high power density (2380 W kg−1) and high energy density (105 Wh kg−1). A “tortoise”-like integrated system is designed as a high-power photo-heat source to realize a reversible and controllable temperature rise up to 3.3–4.1 °C on the “back” with a temperature gradient of the “leg.” Results show that heat release rate at 60 °C and under room-temperature green-light irradiation at 535 nm are higher than those at 45 °C, indicating controllability in time-resolved temperature rise. Based on these results, a thermally controllable dual encoding/reading strategy based on reversible time-resolved thermochromic-patterned display is developed for the first time. Dual encoding/reading information (response time or a specific pattern) can be selectively changed by optimizing isomerization degree or stimulus.

Various photoactive building blocks can be incorporated into porous organic polymers (POPs). The intrinsic properties, such as various synthetic methods, outstanding inherent porosity, easy tunability, rigid conjugated skeletons and high stability, endow the polymeric organic networks with wonderful potential to act as heterogeneous photocatalytic platforms. However, exploitation of efficient synthetic strategies for metal-free and nontoxic heterogenous photocatalysts, and further insights into the photocatalytic process in organic transformations are still necessary. In this context, we report the concise synthesis of two polymeric frameworks (BTP-CMP and TBTP-CMP) incorporated into bithiophene and thiophthene units via a “bottom-up” strategy. BTP-CMP and TBTP-CMP were employed as heterogeneous photocatalysts in the synthesis of benzimidazoles, and exhibited excellent catalytic activity (up to 98% yield, at least 15 iterative runs). Therefore, the thiophene-embedded networks can serve as stable efficient and recyclable heterogeneous photocatalysts. Additionally, based on the catalytic results of control experiments and the energy band structures of the materials and intermediates, a possible photocatalytic reaction mechanism has been proposed.

Phenalenyl (PLY) and its derivatives could form one-dimensional π-aggregates through pancake π–π bonding, which would lead to exotic optoelectronic properties. We will highlight the key aspects of the PLY derivatives from the design strategies to exploration of the electronic properties. Here, we primarily construct alternating boron (B)- and nitrogen (N)-doped PLY π-aggregates: dimer[12], trimer[12-1], trimer[12-2], tetramer[12]2, pentamer[12]2-1, pentamer[12]2-2, and hexamer[12]3. The geometric and electronic structures show that the short intermolecular distances of the π-aggregates drive the formation of pancake π–π bonding. Significantly, the molecular structures show periodic changes in the π-aggregates, but the first hyperpolarizabilities (βtot) present unexpected changes, which are found to increase sharply with increasing even layer thickness due to intermolecular charge transfer. The βtot value of hexamer[12]3 (5.72 × 104 a.u.) is 6.4 times that of tetramer[12]2 (8.95 × 103 a.u.), and is 22.4 times that of dimer[12] (2.55 × 103 a.u.). Thus, constructing π-aggregates can significantly improve the second-order NLO response, which is mainly due to intermolecular charge transfer through pancake π–π bonding of the interlayers.

Water electrolysis is a sustainable and clean method to produce hydrogen fuel via hydrogen evolution reaction (HER). Using stable, effective and low-cost electrocatalysts for HER to substitute expensive noble metals is highly desired. In this paper, by using first-principles calculation, we designed a defect and N-, S-, P-doped penta-graphene (PG) as a two-dimensional (2D) electrocatalyst for HER, and its stability, electronic properties and catalytic performance were investigated. The Gibbs free energy (ΔGH), which is the best descriptor for the HER, is calculated and optimized, the calculation results show that the ΔGH can be 0 eV with C2 vacancies and P doping at C1 active sites, which should be the optimal performance for a HER catalyst. Moreover, we reveal that the larger charge transfer from PG to H, the closer ΔGH is to zero according to the calculation of the electron charge density differences and Bader charges analysis. Ulteriorly, we demonstrated that the HER performance prefers the Volmer–Heyrovsky mechanism in this study.

A 3D printed conformal metasurface, based on a novel dielectric unit cell, is proposed for linear-to-circular polarization conversion. The designed dielectric unit cell comprises a cuboid-shaped dielectric block and a thin square dielectric substrate layer for ease of fabrication with 3D printing technology. Meanwhile, the unit cell can achieve linear-to-circular polarization conversion performance from 14.2 GHz to 20.1 GHz with 3-dB axial ratios (ARs) of 34% and good angular stability within 40°. Then, the unit cell is applied to design conformal linear-to-circular polarization dielectric metasurface converters on cylindrical and spherical surfaces, respectively.

The fabrication procedure of gas sensing films deposited by physical vapor deposition is more compatible with the micro-electro-mechanical system (MEMS) process. However, low sensitivity and high working temperature of gas sensing films limit their application. In this work, tungsten trioxide (WO3) films were deposited on silicon oxide by glancing angle deposition (GLAD), and palladium (Pd) was deposited onto the WO3 layer. Then, the morphology, structure, and nitrogen dioxide (NO2) gas sensing properties of the Pd/WO3 films were studied. The results show that the Pd/WO3 films may comprise discrete Pd islands and columnar WO3 nanorods. The nanostructure can detect 0.5 ppm NO2 at 150 °C with a sensitivity of 1.85 and possesses good selectivity, which can be mainly attributed to large specific surface area of nanorods, catalysis of Pd, and Schottky barrier between Pd and WO3. Therefore, the Pd/WO3 nanostructure prepared by GLAD has great potential in the field of NO2 MEMS sensors.