Tin dioxide nanotubes with N-doped carbon layer (SnO2/N-C NTs) were synthesized through a MoO3 nanorod-based sacrificial template method, dopamine polymerization and calcination process. Applied to the Li-ion battery, SnO2/N-C NTs exhibited excellent electrochemical properties, with a first discharge capacity of 1722.3 mAh·g−1 at 0.1 A·g−1 and a high capacity of 1369.3 mAh·g−1 over 100 cycles. The superior electrochemical performance is ascribed to the N-doped carbon layer and tubular structure, which effectively improves the electrical conductivity of the composites, accelerates the migration of Li+ and electrons, and alleviates the volume change of the anode to a certain extent.
As a structural and functional material with excellent properties, ceramics play an extremely important role in a wide range of industries, including life and production. To expand the range of applications for ceramic materials, ceramics are often joined to metals and then used. Among the physical and chemical joining methods of ceramics to metals, the AMB method is efficient and simple, suitable for industrial applications, and has been a hot topic of research. However, due to the problems of residual stresses caused by the large difference in thermal expansion coefficients between ceramic and metal brazing, composite fillers have become a very worthwhile solution by regulating the physical properties of the brazing material and improving the weld structure. This review describes the wetting principle and application of Ag‒Cu‒Ti active metal filler in the field of ceramic joining, with emphasis on the current stage of composite filler, and discusses the influence on the former brazing properties and organization after the introduction of dissimilar materials.
It is still a challenge to prepare a water- and polymer-based electrospun air filter film with high efficiency filtration, low pressure drop, and good mechanical properties. To address this issue, polyvinyl alcohol (PVA) was employed as the main material, mixing polyethyleneimine (PEI), bamboo-based activated carbon (BAC) and cellulose nanocrystal (CNC) to construct the air filter film by electrostatic electrospinning. In this system, the negatively charged BAC and CNC are fixed in the system through bonding with the positively charged PEI, showing a double adsorption effect. One is the mechanical filtration of the porous network structure constructed by PVA@PEI electrospun nanofibers, and the other is the electrostatic adsorption of PM2.5 on the surface of BAC and CNC. It is significant that the resulting composite air filter displays a high filtration efficiency of 95.86%, a pressure drop of only 59 Pa, and good thermal stability. Moreover, the introduced methyltrimethoxysilane (MTMS) endows it with good water-resistance. Given these excellent performances, this system can provide theoretical and technical references for the development of water- and polymer-based electrospun air filter film.
Flexible strain sensors have been extensively used in human motion detection, medical aids, electronic skins, and other civilian or military fields. Conventional strain sensors made of metal or semiconductor materials suffer from insufficient stretchability and sensitivity, imposing severe constraints on their utilization in wearable devices. Herein, we design a flexible strain sensor based on biphasic hydrogel via an in-situ polymerization method, which possesses superior electrical response and mechanical performance. External stress could prompt the formation of conductive microchannels within the biphasic hydrogel, which originates from the interaction between the conductive water phase and the insulating oil phase. The device performance could be optimized by carefully regulating the volume ratio of the oil/water phase. Consequently, the flexible strain sensor with oil phase ratio of 80% demonstrates the best sensitivity with gauge factor of 33 upon a compressive strain range of 10%, remarkable electrical stability of 100 cycles, and rapid resistance response of 190 ms. Furthermore, the human motions could be monitored by this flexible strain sensor, thereby highlighting its potential for seamless integration into wearable devices.
Flexible humidity sensors are widely used in many fields, such as environmental monitoring, agricultural soil moisture content determination, food quality monitoring and healthcare services. Therefore, it is essential to measure humidity accurately and reliably in different conditions. Flexible materials have been the focusing substrates of humidity sensors because of their rich surface chemical properties and structural designability. In addition, flexible materials have superior ductility for different conditions. In this review, we have summarized several sensing mechanisms, processing techniques, sensing layers and substrates for specific humidity sensing requirements. Aadditionally, we have sorted out some cases of flexible humidity sensors based on different functional materials. We hope this paper can contribute to the development of flexible humidity sensors in the future.
Pore characteristics have been identified as key design parameters for osteoimmunomodulation. The strategy reported here is to create an appropriate immune microenvironment by regulating pore characteristics of scaffolds, thereby promoting early angiogenesis and enhancing osteogenesis. A series of collagen/nano-hydroxyapatite (Col/nHAP) composite scaffolds with ordered lamellar structures and different layer spacings were prepared by mimicking the ordered lamellar topology of the bone matrix. Our research indicated that the layer spacing and ordered topology of the scaffold exerted an important influence on phenotype transformation of macrophages and the secretion of angiogenic factors. The Col/nHAP-O(135) with large layer spacing not only supported cell attachment and diffusion in vitro, but also promoted early angiogenesis by timely switching from M1 to M2 macrophage phenotype. In vivo data showed that the layer spacing and the ordered structure of the scaffold synergistically regulated the inflammatory response and triggered macrophages to secrete more angiogenesis related cytokines. Col/nHAP-O(135) considerably promoted the neovascularization and new bone formation in the defect site, indicating that Col/nHAP-O(135) could significantly enhance the osteogenic activity of stem cells with the involvement of macrophages.
Herein, a novel visible-light-responsive photocatalyst with high efficiency was firstly synthesized at room temperature. The mild synthetic method resulted in a uniform spherical triazine-based covalent organic framework (TrCOF2) with ultra-high specific surface area as well as chemical stability. Due to the synergistic effect between the self-assembled uniform spherical structure and the abundant triazine-based structure, photoelectron–hole pairs were efficiently separated and migrated on the catalysts. On this basis, TrCOF2 was successfully applied to efficiently degrade bisphenol A (BPA). More than 98% of BPA was deraded after 60 min of visible light treatment, where the active specie of •O2 − played a vital role during the degradation of BPA. The holes of TrCOF2 could produce O2 by direct reaction with water or hydroxide ions. Simultaneously, photoelectrons can be captured by O2 to generate •O2 −. Moreover, density functional theory (DFT) calculations proved the outstanding ability of the exciting electronic conductivity. Remarkably, a reasonable photocatalytic mechanism for TrCOF2 catalysts was proposed. This research can provide a facile strategy for the synthesis of TrCOFs catalysts at room temperature, which unfolds broad application prospects in the environmental field.
Rechargeable aqueous zinc-ion batteries (AZIBs) are the most promising candidates for the energy storage due to their high safety, rich resources, and large specific capacity. However, AZIBs using neutral or slightly acidic electrolytes still face side effects and zinc dendrites on the anode surface. To stabilize the Zn anode, a chemically stable and multi-functional coating of polyvinylidene fluoride (PVDF) and 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) was prepared on the Zn surface. The anhydride groups in 6FDA can improve the hydrophilicity, promoting the migration of zinc ions. Besides, PVDF is compatible with 6FDA because of the presence of organic F-containing groups, which can also effectively reduce the nucleation overpotential and exhibit the dendrite-free Zn deposition/stripping. The PVDF/6FDA@Zn symmetric cell can cycle for 5000 h at a current density of 0.5 mA·cm−2, maintaining the extremely low polarization voltage and overpotential of 28 and 8 mV, respectively. The PVDF/6FDA@Zn||MnO2 full cell can remain a specific capacity of ~90 mAh·g−1 after 2000 cycles at 1.5 A·g−1. This simple method achieves a reversible Zn anode, providing an inspiring strategy for ultra-long-cycle AZIBs.
Nitrogen atom doping has been found to enhance the electrochemical performance of porous carbon (PC). In this study, hollow tubular nitrogen-doped porous carbon (N/PC) was synthesized using polyvinylpyrrolidone as the carbon–nitrogen source and fibrous brucite as the template through carbonization. The effects of nitrogen and argon protective atmospheres on the nitrogen content, the specific surface area (SSA), and electrochemical properties of N/PC were investigated. The results showed that compared with N/FBC-Ar, N/FBC-N2 prepared in nitrogen protective atmosphere had a higher nitrogen content and a larger proportion of pyrrolic nitrogen (N-5) and pyridinic nitrogen (N-6). N/FBC-N2 displayed a specific capacitance (C) of 194.1 F·g−1 at 1 A·g−1, greater than that of N/FBC-Ar (174.3 F·g−1). This work reveals that the nitrogen doping with a higher nitrogen content in nitrogen protective atmosphere is more favorable. Furthermore, a larger proportion of pyrrolic nitrogen and pyridinic nitrogen in the doped nitrogen atoms significantly enhances the electrochemical performance.
Uncontrolled hemorrhage resulting from traumas causes severe health risks. There is an urgent need for expeditious hemostatic materials to treat bleeding incidents. Here, we developed a natural protein-based hemostatic sponge extracted from nonmulberry cocoons that exhibited rapid coagulation and effective absorption. We first built a degumming and dissolution system suitable for the Dictyoploca japonica cocoons to obtain regenerated silk fibroin (DSF). The DSF was then combined with carboxymethyl chitosan (CMCS) by glutaraldehyde (GA) crosslinking to ensure the structural stability of sponges. The resulting DSF–CMCS–GA exhibited remarkable hemostatic properties, displaying the highest absorption rate. It also demonstrated comparable efficacy to commercial hemostatic sponges. The blood-clotting index and hemolysis test showed that the prepared sponge possessed hemostatic activity and good hemocompatibility. Compared with mulberry silk fibroin hemostatic sponges (SF–CMCS–GA), DSF–CMCS–GA showed slightly better effects, making them a potential alternative to mulberry silk. In conclusion, our study introduces the use of Dictyoploca japonica silk fibroin for hemostasis, highlighting the exploitation of wild silkworm resources and providing an excellent silk fibroin-based hemostatic sealant for acute accident wounds and biomedical applications involving massive hemorrhage.
Electrospun nanofibers with highly efficient photothermal/electrothermal performance are extremely popular because of their great potential in wearable heaters. However, the lack of necessary wearable properties such as high mechanical strength and quick response of electrospun micro/nanofibers seriously affects their practical application. In this work, a technical route combining electrospinning and surface modification technology is proposed. The 3-triethoxysilylpropylamine-polyacrylonitrile@copper sulfide (K-PAN@CuS) composite fabric was achieved by modifying the original electrospinning PAN fiber and subsequently loading CuS nanoparticles. The results show that the break strength of the K-PAN@CuS fabric was increased by 10 times compared to that of the original PAN@CuS fabric. Furthermore, the saturated temperature of the K-PAN@CuS fabric heater could reach 116 °C within 15 s at a relatively low voltage of 3 V and 120.3 °C within 10 s under an infrared therapy lamp (100 W). In addition, due to its excellent conductivity, such a unique structural design enables the fiber to be closely attached to the human skin and helps to monitor human movements. This K-PAN@CuS fabric shows great potential in wearable heaters, hyperthermia, all-weather thermal management, and in vitro physical therapy.
Monoclonal antibodies have been used in many diseases, but how to improve their delivery efficiency is still a key issue. As the modification of zwitterionic polymers can maintain the stability and biological activity of monoclonal antibodies, in this study, zwitterionic monomers, sulfobetaine methacrylate (SBMA), and 3-[[2-(methacryloyloxy) ethyl] dimethylammonio] propionate (CBMA) were used to prepare monoclonal antibody-loaded zwitterionic nanoparticles with the aid of the crosslinker of MMP-2 enzyme-responsive peptide which was a rapid synthesis process under mild conditions. The results from dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM) indicated that a series of zwitterionic nanoparticles had been successfully prepared by the in situ free radical polymerization using the MMP-2 enzyme-responsive peptide as the cross-linking agent. These nanoparticles were spherical with the sizes of (18.7±1.9) nm (SBMA nanoparticle) and (18.2±2.1) nm (CBMA nanoparticle), and the surface contained zwitterionic polymers. It was revealed that they had no cytotoxicity, could be released in tumor microenvironment by enzyme to inhibit the growth of tumor cells, and was able to effectively penetrate endothelial cells (> 2%) by transwell. Therefore, the development of this strategy has a great prospect for the delivery of monoclonal antibodies.
In this work, Fe3O4 nanoparticles (NPs) loaded inside and outside halloysite nanotubes (HNTs) were prepared and developed as the heterogeneous Fenton-like catalysts for the removal of representative organic pollutants. Characterization results indicated that the samples with Fe3O4 NPs loaded outside the HNTs lumen (Fe3O4/HNTs) and inside the HNTs lumen (Fe3O4@HNTs) were successfully prepared. Both samples had typical magnetic hysteresis loops, while Fe3O4@HNTs exhibited higher magnetization intensity. The comparative experiments showed that Fe3O4@HNTs had better Fenton-like catalytic ability than that of Fe3O4/HNTs in the degradation of various organic pollutants. Taking Rhodamine B (RhB) as an example, the adsorption thermodynamics and kinetics of RhB onto Fe3O4/HNTs and Fe3O4@HNTs were also investigated. The comparative results demonstrated that the adsorption ability of Fe3O4/HNTs was better than that of Fe3O4@HNTs. Moreover, the dissolved concentration of Fe2+ and production amount of hydroxyl radical (·OH) in the Fe3O4@HNTs-H2O2 system were significantly higher than those in the Fe3O4/HNTs-H2O2 system. Based on aforementioned comparison, the nano-confinement effect in the Fe3O4@HNTs-H2O2 system was verified. This work provides meaningful guidance for the cheap and convenient design of nanoreactors for Fenton-like applications.
Metal–organic frameworks (MOFs) have attracted widespread attention due to their regular structures, multiple material centers, and various ligands. They are always considered as one kind of ideal templates for developing highly sensitive and selective gas sensors. In this study, the advantages of MOFs with the high specific surface area (71.9891 m2·g−1) and uniform morphology were fully utilized, and urchin-like SnO2 nanowires were obtained by the hydrothermal method followed by the calcination using Sn-MOFs consisting of the ligand of C9H6O6 (H3BTC) and Sn/Ce center ions as sacrificial templates. This unique urchin-like nanowire structure facilitated gas diffusion and adsorption, resulting in superior gas sensitivity. A series of Ce-doped SnO2 nanowires with different doping ratios were synthesized, and their gas sensing properties towards formaldehyde were studied. The resulted Ce-SnO2 was revealed to have high sensitivity (201.2 at 250 °C), rapid response (4 s), long-term stability, and good repeatability for formaldehyde sensing, and the gas sensing mechanism of Ce-SnO2 exposed to formaldehyde was also systematically discussed.
Size effects and compositions constitute new properties for inorganic particles in different application fields. The physical method has recently attracted more attention in the preparation of inorganic materials. Herein, a low-cost, eco-friendly, simple-operating, and time-saving technique, named electrical discharge, is reviewed in relation to developments from the nature of this technique in different dielectric media to the practical experience in controlling the main processing parameters, apparatuses, types of discharge, from the various structures and components to the wide applications. The development of the electrical discharge technique will play an important role in improving the technology to prepare superfine inorganic particles with high purity. Meanwhile, electrical discharge contributes to easily mixing solid materials from the atomic scale to several micrometers with different structures. Moreover, metal oxides or doping materials are accessible as the dielectric medium is changed. Considering some excellent advantages, new inorganic particles exploited through the electrical discharge method will promise to be the most rewarding in some potential applications.
To determine the contribution of non-repetitive domains to the bioactivity of the heavy chain in silk fibroin (SF) macromolecules, a gene motif f(1) encoding this fragment and its multimers (f(4) and f(8)) were biosynthesized from Escherichia coli BL21. Based on the positive application potential of SF materials for the vascular tissue engineering, this study focused on examining the active response of these polypeptides to vascular endothelial cells. Biosynthetic polypeptides F(1), F(4), and F(8) were separately grafted onto the surfaces of bioinert polyethylene terephthalate (PET) films, resulting in remarkable improvements in the spread and proliferation of human umbilical vein endothelial cells (HUVECs). Using the same grafting dose, the activity of cells on polypeptide-modified PET films enhanced with the increase of the molecular weight of those grafted polypeptides from F(1) to F(8). Meanwhile, the growth of cells on the surface of the alkaline-treated PET film was improved, indicating that the hydrophilicity of the surface material had influence on the growth of HUVECs. Moreover, on surfaces with the same water contact angle, the spread and proliferation activity of cells on PET films were significantly lower than those on polypeptide-modified PET films.
In the field of bone defect repair, critical requirements for favorable cytocompatibility and optimal mechanical properties have propelled research efforts towards the development of composite materials. In this study, carbon nanotubes/polylactic acid/hydroxyapatite (CNTs/PLA/HA) scaffolds with different contents (0.5, 1, 1.5 and 2 wt.%) of CNTs were prepared by the thermally induced phase separation (TIPS) method. The results revealed that the composite scaffolds had uniform pores with high porosities over 68% and high through performances. The addition of CNTs significantly enhanced the mechanical properties of resulted PLA/HA, in which the 1.5 wt.% CNTs/PLA/HA composite scaffold demonstrated the optimum mechanical behaviors with the bending elastic modulus of (868.5 ± 12.34) MPa, the tensile elastic modulus of (209.51 ± 12.73) MPa, and the tensile strength of (3.26 ± 0.61) MPa. Furthermore, L929 cells on the 1.5 wt.% CNTs/PLA/HA scaffold displayed good spreading performance and favorable cytocompatibility. Therefore, it is expected that the 1.5 wt.% CNTs/PLA/HA scaffold has potential applications in bone tissue engineering.
The choice of cathode and anode materials for electrochromic devices plays a key role in the performance of electrochromic smart windows. In this research, WO3/Ag and TiO2/NiO composite thin films were separately prepared by the hydrothermal method combined with electrodeposition. The electrochromic properties of the single WO3 thin film were optimized, and TiO2/NiO composite films showed better electrochromic performance than that of the single NiO film. WO3/Ag and TiO2/NiO composite films with excellent electrochromic properties were respectively chosen as the cathode and the anode to construct a WO3/Ag‒TiO2/NiO electrochromic device. The response time (tc = 4.08 s, tb = 1.08 s), optical modulation range (35.91%), and coloration efficiency (30.37 cm2·C−1) of this electrochromic device are better than those of WO3‒NiO and WO3/Ag‒NiO electrochromic devices. This work provides a novel research idea for the performance enhancement of electrochromic smart windows.
The in vitro expansion of stem cells is important for their application in different life science fields such as cellular tissue and organ repair. An objective of this paper was to achieve static cell culture in vitro through peptide hydrogel-supported microspheres (MSs). The peptides, with their gel-forming properties, microstructures, and mechanical strengths characterized, were found to have good support for the MSs and to be injectable. The internal structures of poly(L-lactic acid) microspheres (PLLA-MSs) and polystyrene microspheres (PS-MSs) made in the laboratory were observed and statistically analyzed in terms of particle size and pore size, following which the co-cultured MSs with cells were found to have good cell adhesion. In addition, three-dimensional (3D) culturing of cells was performed on the peptide and microcarrier composite scaffolds to measure cell viability and cell proliferation. The results showed that the peptides could be stimulated by the culture medium to self-assembly form a 3D fiber network structure. Under the peptide-MS composite scaffold-based cell culture system, further enhancement of the cell culture effect was measured. The peptide-MS composite scaffolds have great potential for the application in 3D cell culture and in vitro cell expansion.
Diabetic foot ulcer (DFU) often evolves into chronic wounds that resist healing over an extended period, sometimes necessitating amputation in severe cases. Traditional wound management approaches generally fail to control these chronic sores successfully. Thus, it arouses a huge demand in clinic for a novel wound dressing to treat DFU effectively. Hydrogel as an ideal delivery system exhibits excellent loading capacity and sustainable release behavior. It also boasts tunable physical and chemical properties adaptable to diverse biomedical scenarios, making it a suitable material for fabricating functional wound dressings to treat DFU. The hydrogel dressings are classified into hemostatic, antibacterial and anti-inflammatory, and healing-promoting hydrogel dressings by associating the pathogenesis of DFU in this paper. The design and fabrication strategies for the dressings, as well as their therapeutic effects in treating DFU, are extensively reviewed. Additionally, this paper highlights future perspectives of multifunctional hydrogel dressings in DFU treatment. This review aims to provide valuable references for material scientists to design and develop hydrogel wound dressings with enhanced capabilities for DFU treatment, and to further translate them into the clinic in the future.
Electrolyte interface resistance and low ionic conductivity are essential issues for commercializing solid-state lithium metal batteries (SSLMBs). This work details the fabrication of a double-layer solid composite electrolyte (DLSCE) for SSLMBs. The composite comprises poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF‒HFP) and poly(methyl methacrylate) (PMMA) combined with 10 wt.% of Li6.4La3Zr1.4Ta0.6O12 (LLZTO), synthesized through an ultraviolet curing process. The ionic conductivity of the DLSCE (2.6 × 10−4 S·cm−1) at room temperature is the high lithium-ion transference number (0.57), and the tensile strength is 17.8 MPa. When this DLSCE was assembled, the resulted LFP/DLSCE/Li battery exhibited excellent rate performance, with the discharge specific capacities of 162.4, 146.9, 93.6, and 64.0 mA·h·g−1 at 0.1, 0.2, 0.5, and 1 C, respectively. Furthermore, the DLSCE demonstrates remarkable stability with lithium metal batteries, facilitating the stable operation of a Li/Li symmetric battery for over 200 h at both 0.1 and 0.2 mA·cm−2. Notably, the formation of lithium dendrites is also effectively inhibited during cycling. This work provides a novel design strategy and preparation method for solid composite electrolytes.
In situ carbon-coated Co3Se4/CoSe2 (CoxSey) nanoparticles (NPs) attached on three-dimensional (3D) reduced graphene oxide (rGO) sheets were skillfully developed in this work, which involved the environment-friendly hydrothermal method, freeze drying, and selenide calcination. Within the structure, the glucose-derived carbon layer exhibited significantly homogeneous dispersion under an argon environment. This structure not only has enhanced stability, but also can effectively mitigate the volume swell of CoxSey particles. The resulted Co3Se4/CoSe2@C/rGO (CSe@C/rGO) exhibited a specific surface area (SSA) of 240.9 m2·g−1, offering more electrochemically active sites for the storage of energy related to lithium ions. The rGO matrix held exceptional flexibility and functional structural rigidity, facilitating the swift ion intercalation and ensuring the high conductivity and recyclability of the structure. When applied to anodes designed for lithium-ion batteries (LIBs), this material demonstrated distinguished rate and ultra-high reversible capacity (872.98 mA·h·g−1 at 0.5 A·g−1). Meanwhile, its capacity retention reached 119.5% after 500 cycles at 2 A·g−1, with a coulombic efficiency of 100%. This work potentially paves the way for generating fast and powerful metal selenide anodes and initiating LIBs with good performance.
Porous flower-like SnO2/CdSnO3 microstructures self-assembled by uniform nanosheets were synthesized using a hydrothermal process followed by calcination, and the sensing performance was measured when a gas sensor, based on such microstructures, was exposed to various volatile organic compound (VOC) gases. The response value was found to reach as high as 100.1 when the SnO2/CdSnO3 sensor was used to detect 100 ppm formaldehyde gas, much larger than those of other tested VOC gases, indicating the high gas sensitivity possessed by this sensor especially in the detection of formaldehyde gas. Meanwhile, the response/recovery process was fast with the response time and recovery time of only 13 and 21 s, respectively. The excellent gas sensing performance derive from the advantages of SnO2/CdSnO3, such as abundant n–n heterojunctions built at the interface, high available specific surface area, abundant porosity, large pore size, and rich reactive oxygen species, as well as joint effects arising from SnO2 and CdSnO3, suggesting that such porous flower-like SnO2/CdSnO3 microstructures composed of nanosheets have a high potential for developing gas sensors.
This paper describes how to produce a wearable dry electrode at a reasonable cost and how to use it for the monitoring of biopotentials in electrocardiography. Smart textiles in wearable technologies have made a great advancement in the health care management and living standards of humans. Graphene was manufactured using the low-cost single-step process, laser ablation of polyimide, a commercial polymer. Graphene dispersions were made using solvent isopropyl alcohol which has low boiling point, nontoxicity, and environmental friendliness. After successive coating of the graphene dispersion on the cotton fabric to make it conductive, the sheet resistance of the resulting fabric dropped to 3% of its initial value. The laser-induced graphene (LIG) cotton dry electrodes thus manufactured are comparable to Ag/AgCl wet electrodes in terms of the skin-to-electrode impedance, measuring between 78.0 and 7.2 kΩ for the frequency between 40 Hz and 1 kHz. The LIG cotton electrode displayed a signal-to-noise ratio of 20.17 dB. Due to its comfort, simplicity, and good performance over a longer period of time, the textile electrode appears suited for medical applications.
The solar-to-hydrogen conversion using the photoelectrochemical (PEC) method is a practical approach to producing clean energy. However, it relies on the availability of photocatalyst materials. In this work, a novel photocatalyst comprising molybdenum telluride quantum dots (MoTe2 QDs)-modified titanium dioxide nanorods (TiO2 NRs) was prepared for the enhancement of the PEC water splitting performance after combination with a Al2O3 layer using the atomic layer deposition (ALD) technique. MoTe2 QDs were initially prepared, and then they were loaded onto TiO2 NRs using a warm water bath-based heating method. After a layer of Al2O3 was deposited onto resulted TiO2 NRs/MoTe2 QDs, the composite TiO2 NRs/MoTe2 QDs/Al2O3 was finally obtained. Under simulated sunlight (100 mW·cm−2), such a composite exhibited a maximum photocurrent density of 2.25 mA·cm−2 at 1.23 V (versus RHE) and an incident photon-to-electron conversion efficiency of 69.88% at 380 nm, which are 4.33 and 6.66 times those of pure TiO2 NRs, respectively. Therefore, the composite photocatalyst fabricated in this work may have promising application in the field of PEC water splitting, solar cells and other photocatalytic devices.
There are still many challenges including low conductivity of cathodes, shuttle effect of polysulfides, and significant volume change of sulfur during cycling to be solved before practical applications of lithium–sulfur (Li–S) batteries. In this work, (FeO)2FeBO3 nanoparticles (NPs) anchored on interconnected nitrogen-doped carbon nanosheets (NCNs) were synthesized, serving as sulfur carriers for Li–S batteries to solve such issues. NCNs have the cross-linked network structure, which possess good electrical conductivity, large specific surface area, and abundant micropores and mesopores, enabling the cathode to be well infiltrated and permeated by the electrolyte, ensuring the rapid electron/ion transfer, and alleviating the volume expansion during the electrochemical reaction. In addition, polar (FeO)2FeBO3 can enhance the adsorption of polysulfides, effectively alleviating the polysulfide shuttle effect. Under a current density of 1.0 A·g−1, the initial discharging and charging specific capacities of the (FeO)2FeBO3@NCNs-2/S electrode were obtained to be 1113.2 and 1098.3 mA·h·g−1, respectively. After 1000 cycles, its capacity maintained at 436.8 mA·h·g−1, displaying a decay rate of 0.08% per cycle. Therefore, combining NCNs with (FeO)2FeBO3 NPs is conducive to the performance improvement of Li–S batteries.
In this work, C@Fe3O4 composites were prepared through a typical template method with emulsified asphalt as carbon source, ammonium ferric citrate as transition metal oxide precursor, and NaCl as template. As an anode for lithium-ion batteries, the optimized C@Fe3O4-1:2 composite exhibits an excellent reversible capacity of 856.6 mA·h·g−1 after 100 cycles at 0.1 A·g−1 and a high capacity of 531.1 mA·h·g−1 after 300 cycles at 1 A·g−1, much better than those of bulk carbon/Fe3O4 prepared without NaCl. Such remarkable cycling performance mainly benefits from its well-designed structure: Fe3O4 nanoparticles generated from ammonium ferric citrate during pyrolysis are homogenously encapsulated in graphitized and in-plane porous carbon nanocages derived from petroleum asphalt. The carbon nanocages not only improve the conductivity of Fe3O4, but also suppress the volume expansion of Fe3O4 effectively during the charge‒discharge cycle, thus delivering a robust electrochemical stability. This work realizes the high value-added utilization of low-cost petroleum asphalt, and can be extended to application of other transition-metal oxides-based anodes.
The absorption of high-viscosity oil by traditional oil absorbing materials has always been a challenge. So there is an urgent need to solve the problem of slow absorption of high-viscosity oil. In this work, an emulsion composed of polydimethylsiloxane (PDMS), carbon black (CB) and waterborne polyurethane (solid content 40%) was sprayed on the melamine foam (MF). After volatilization of organic solvents, the photothermal material CB was fixed on the MF framework, making it photothermal. By raising the temperature of the modified foam to accelerate the internal thermal movement of high-viscosity oil molecules around the foam, intermolecular forces are reduced, thereby accelerating the separation process. The absorption capacity of this modified MF towards organic solvents and oil is up to 79 times its own weight. In addition, the mechanical properties of the modified foam are improved to a certain extent, more conducive to the continuous oil–water separation. This photothermal absorption material provides ideas for the rapid removal of high-viscosity oil, heavy oil, etc.
The coating-modified magnesium (Mg) alloys exhibit controllable corrosion resistance, but the insufficient antibacterial performance limits their clinical applications as degradable implants. Superhydrophobic coatings show excellent performance in terms of both corrosion resistance and inhibition of bacterial adhesion and growth. In this work, a hydroxyapatite (HA)/palmitic acid (PA) superhydrophobic composite coating was fabricated on the Mg alloy by the hydrothermal technique and immersion treatment. The HA/PA composite coating showed superhydrophobicity with a contact angle of 153° and a sliding angle of 2°. The coated Mg alloy exhibited excellent corrosion resistance in the simulated body fluid, with high polarization resistance (77.10 kΩ·cm2) and low corrosion current density ((0.491 ± 0.015) μA·cm−2). Meanwhile, the antibacterial efficiency of the composite coating was over 98% against E. coli and S. aureus in different periods. The results indicate that the construction of such superhydrophobic composite coating (HA/PA) on the Mg alloy can greatly improve the corrosion resistance of Mg alloy implants within the human body and avoid bacterial infection during the initial stages of implantation.
Zinc-based flow battery is an energy storage technology with good application prospects because of its advantages of abundant raw materials, low cost, and environmental friendliness. The chemical stability of zinc electrodes exposed to electrolyte is a very important issue for zinc-based batteries. This paper reports on details of chemical stability of the zinc metal exposed to a series of solutions, as well as the relationship between the morphological evolution of zinc electrodes and their properties in an alkaline medium. Chemical corrosion of zinc electrodes by the electrolyte will change their surface morphology. However, we observed that chemical corrosion is not the main contributor to the evolution of zinc electrode surface morphology, but the main contributor is the Zn/Zn2+ electrode process. The morphological evolution of zinc electrodes was controlled by using ionic liquids, 1-ethyl-3-methylimidazolium acetate (EMIA), and 1-propylsulfonic-3-methylimidazolium tosylate (PSMIT), and the electrode performance was recorded during the morphological evolution process. It was observed that the reversible change of zinc electrode morphology was accompanied by better electrode performance.
