As-obtained Composites Research Articles

Advanced X/γ-Ray-Shielding Materials Enabled by the In Situ Generation of Cerium-Tungsten Nanoparticles Within Regenerated Collagen Fibers.

Advanced X- and γ-ray-shielding materials are conventionally designed and fabricated via the uniform dispersion of high-Z elements into the substrate. These soluble high-Z elements considerably reduced the particle size of functional components; however, the as-obtained composites exhibited weak absorption region at 40-80keV and poor water resistance. To address these issues, such materials are fabricated by introducing cerium and tungsten into regenerated collagen fibers (RCFs) using a "dual impregnation-desolvation" strategy. The uniform dispersion of functional components is achieved via the in situ generation of cerium-tungsten nanoparticles (CeW NPs) under multiple impregnating and desolvating cycles; as a result, the CeW NPs achieved an ultrasmall particle size of 17.15nm. Benefiting from the ultrasmall particle size and uniform dispersion of CeW NPs, the fabricated CeW-RCF composites exhibit satisfactory X- and γ-ray-shielding capabilities with an ultrahigh mass attenuation coefficient (MAC) of 5.9cm2g-1 at 83keV, higher than that of lead plates. The CeW-RCF composites also exhibit outstanding mechanical strength, low density, and high air permeability, demonstrating their superior wearability. This work provides novel insights into the design and fabrication of advanced X- and γ-ray-shielding materials with high radiation-shielding performance and enhanced wearability.

Simple construction of efficient graphite supported NiCoCu functional catalysts for methanol oxidation reaction using mechanical milling

A low-energy methodology has been proposed to synthesized Ni-based binary and ternary compounds from M-acetylacetonates (M = Ni, Co and Cu) and mechanical milling (MM) to be used as electrocatalysts for the methanol oxidation reaction in alkaline medium (1 M KOH). The strategies used in this study expand the possibilities of obtaining materials with efficient electrocatalytic activities from noble metal-free catalysts, while reducing the production cost. The prepared electrodes were characterized to evaluate changes in the thermal decomposition, as well as chemical, structural, morphological and microstructural changes with the composition. Electrochemical performance was evaluated by conventional methods such as cyclic voltammetry and electrochemical impedance spectroscopy (EIS). The series of Ni-based catalysts demonstrated that after MM the composites integrate with oxides of the individual metallic materials without the formation of solid solutions. The electrocatalytic mass activities of the as-obtained composites were found in the following order: Ni0.80Co0.10Cu0.10/C (1181.14 A/g) ≅ Ni0.8Cu0.2/C (1124.45 A/g) > Ni0.80Co0.05Cu0.15/C (254.50 A/g) > Ni0.80Co0.15Cu0.05/C (209.34 A/g) > Ni0.8Co0.2/C (136.64 A/g). Among them, Ni0.80Co0.10Cu0.10/C showed the greatest stability and the leastwest charge transfer resistance that ranges between 0.28 and 0.80 Ω depending on the methanol concentration, and also presented activities higher than those of the commercial Pt/C catalysts. The results demonstrate that with this simple method, it is possible to modulate the electronic structure reducing CO poisoning on the surface of the catalysts and act as an alternative to replace high-cost noble metals during energy conversion from methanol.

Fabrication of highly luminescent and thermally stable composites of sulfur nanodots through surface modification and assembly.

Sulfur nanodots (S-dots) have emerged as a promising luminescent material to excel over traditional heavy metal-based quantum dots. However, their relatively low emission efficiency and poor thermal stability in the solid state have limited their wide applications in photoelectric devices. In this work, highly luminescent, with a photoluminescence quantum yield higher than 50%, and thermally stable composites of S-dots were produced through modulating their surface states and aggregation behaviors by introducing pyromellitic dianhydride (PMDA) and benzoyleneurea (BEU), respectively. PMDA eliminated the relatively short-lived surface states and defects on the surface of S-dots and BEU regulated the aggregation states and facilitated the energy transfer from BEU to S-dots. The as-obtained composites also showed significantly improved thermal stability compared to S-dots, aided by the hydrophobic chemical groups and dense matrix of PMDA and BEU, which extended their applications in fabricating light-emitting diodes. Our presented results provide a new approach to produce highly luminescent S-dots, which widen their applications in the fields of bioimaging, sensing, photoelectric devices, and environmental science.

‘MoS2-coated nitrogen/oxygen co-doped carbon nanocages composite as active material for supercapacitor electrodes

Nitrogen/oxygen co-doped carbon nanocages (NOCN) have been deemed as promising materials in renewable energy-storage applications. Herein, we report a facile one-pot hydrothermal approach for formation of three-dimensional (3D) flower-like MoS2 nanoflakes/NOCN composite (MoS2@NOCN) with excellent storage properties as anode for supercapacitor. As a result, ultrathin MoS2 nanosheets were vertically grown onto the surface of NOCN, which can prevent sheet aggregation and provide a rapid pathway for electron transfer. The as-prepared MoS2@NOCN composites were characterized by electrochemical measurements to demonstrate the supercapacitor performance. The results indicate that MoS2@NOCN-3 exhibited a high specific capacitance (240.8 F g−1 at 0.5 A g−1) and excellent rate performance (approximately 46.4 % from 1 A g−1 to 10 A g−1). The as-obtained composites demonstrated their potential applications in supercapacitor electrode materials.

3D hierarchical NiCo2O4@Co3S4@MnS@PPy core-sheath nanowire arrays as high-performance electrode for all-solid-state asymmetric supercapacitors

To cater to the mushrooming advanced energy storage devices need, designing and preparing novel electrode materials with excellent electrochemical properties (including high capacitance and prominent cycling stability) are urgent but challenging. Here, we successfully synthesized 3D hierarchical NiCo2O4@Co3S4@MnS@PPy (NC@CS@MS@PPy) core-sheath nanowire arrays grown on highly conductive carbon cloth using a multistage process. Owing to a lot of synergy between the multiple components in the as-obtained composite, the prepared electrode material indicates an excellent specific capacitance of 2.67 F cm−2 at 1 mA cm−2 or 2557.58 F g−1 at 1 A g−1 and high cycling stability (83.64 % capacitance retention after 20,000 cycles even at a high current density of 20 mA cm−2). When coupled with the activated carbon (AC, as a negative electrode), the assembled all-solid-state NC@CS@MS@PPy//AC asymmetric supercapacitor (ASC) device showed outstanding electrochemical properties with a high area specific capacitance 684.38 mF cm−2 at 3 mA cm−2 and better long-term cycling stability (96.76 % retention of the initial capacitance after 20,000 cycles). More importantly, by taking advantaging of the multiple compositional merits and structural features of the positive electrode, the device delivered the highest energy density of 81.1 Wh kg−1 at 800 W kg−1 and retained 26.2 Wh kg−1 at the highest power density of 16 KW kg−1. Furthermore, two ASCs connected in series powered 20 red light-emitting diodes (LEDs) for >10 min. This work manifests that the prepared hierarchical NC@CS@MS@PPy core-sheath nanowire arrays have impressive potential as high-performance electrodes for supercapacitor.

A novel glutaraldehyde cross-linked chitosan@acid-activated bentonite composite for effective Pb (II) and Cr (VI) adsorption: Experimental and theoretical studies

In this study, a novel glutaraldehyde cross-linked chitosan@acid-activated bentonite composite (CsG@AAB) was synthesized from crab waste, glutaraldehyde, and acid-activated bentonite (AAB). The as-obtained composite was used as an adsorbent for the efficient removal of Pb(II) and Cr(VI) from the aqueous solutions. The adsorbent was characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and Braeuer–Emmett–Teller (BET) analyses. The effects of factors such as initial metal ion concentration, contact time, temperature, adsorbent dosage, and pH on Pb(II) and Cr(VI) adsorption were investigated, and related adsorption parameters were determined. Characterization results indicate that chitosan entered into the bentonite interlayer. BET surface area and point of zero charge (pHPZC) of the biocomposite were 85.2 m2/g and 6.3, respectively. Both metal ions uptake was rapid while adsorption was highly dependent on solution pH. The monolayer adsorption capacity was 452.78 mg g−1 for Pb(II) and 284.14 mg g−1 for Cr(VI), respectively at 25 °C. The adsorption kinetics were explained using the PSO model. The adsorption thermodynamic process was endothermic and spontaneous. The adsorption mechanism was explained by theoretical calculations and was in good agreement with the experimental results. Physisorption (van der Waals force, pore-filling), chemisorption (both inner and outer-sphere complexes), ion exchange, electrostatic interaction, and surface precipitation were the main mechanisms of metal ions adsorption. The results of this study suggest that the CsG@ AAB composite is promising for Pb(II) and Cr(VI) uptake and can be potential adsorption for decontamination of other pollutants from real wastewater streams.

Mechanically stable superhydrophobic coating of crosslinked polymer composite with self-healing ability

Sustainable superhydrophobicity is of significance for practical application of superhydrophobic coatings. We fabricated a mechanically stable superhydrophobic coating with self-healing performance by spray-coating a composite suspension of poly(vinyl butyral)-hexamethylene diisocyanate and octadecylamine (PVB-HDI/ODA) on various substrates. In the as-obtained composite, PVB-HDI formed 3D self-crosslinked polymer networks which not only impart the coating with high mechanical stability but also provide strong bonding force between the coating and the substrate, and ODA formed pedal-like structures which roughened the coating surface with low surface energy. Consequently, the coating possessed superhydrophobicity with a water contact angle up to 163.9° and a sliding angle lower to 1.0°. Notably, the as-obtained coating sustained its water repellency even after being exposed to various mechanical and chemical treatments. Moreover, the coating exhibited a self-healing ability in superhydrophobicity against O2 plasma etching. Such mechanical and chemical stabilities with self-healing ability are favourable to the superhydrophobic coating to prolong the lifespan for practical applications.

ZIF-67 derived Co@carbon nanotubes anchored on carbon fiber for efficient microwave absorption and mechanical enhancement

Rational design of multifunctional and high-performance electromagnetic wave (EMW) absorbers is highly desirable but still remains a challenge. Herein, the 3D heterostructural Co@carbon nanotubes/carbon fiber (Co@CNTs/CF) hybrids derived from ZIF-67/CF were successfully fabricated via the in-situ synthesis of ZIF-67 on CF and subsequent catalytic chemical vapour deposition. Intriguingly, the as-obtained composites acquire adjustable EMW absorption and favorable mechanical properties simultaneously. Specifically, taking advantage of adequate conductive paths, plentiful heterogeneous interfaces, suitable defect vacancies, appropriate magnetic loss, as well as optimized impedance matching, Co@CNTs/CF delivers a brilliant EMW absorption intensity of −45.11 dB at only 1.15 mm together with a broad effective absorption bandwidth (EAB) of 4.0 GHz (1.23 mm), and an unexpected minimal reflection loss up to −65.63 dB (3.84 GHz) coupled with an EAB of 3.6 GHz at merely 1.09 mm, respectively. In addition, the tunable EAB can be achieved in 2.6–18 GHz, covering 96 % of the test frequency by changing the absorber thickness from 0.93 to 5.0 mm (29 wt%). Moreover, the maximum radar cross section reduction can reach 48.8 dBm2. The uniform layer of CNTs with moderate crystallinity also enables Co@CNTs/CF to improve the tensile strength and Weibull modulus compared to unsized CF. This study paves a novel avenue for developing multifunctional materials based on CF through an efficient, controllable and low-cost approach.

Nest-like hollow Cu-doped Co/CoO/C microspheres derived from spherical Co-ZIF with controllable microwave absorption performance

Spherical Co-ZIF-derived nest-like hollow Cu-doped Co/CoO/C microspheres are obtained by a high-temperature calcination treatment, where a facile mixing method is used to synthesize the Cu/Co-ZIF precursor. During the carbonization process at high temperatures, carbon nanotubes are in-situ grown on the microspherical surface to form interlinked conduction networks. Adjusting the calcination temperature can effectively control the degree of graphitization, leading to the diverse electromagnetic performance. When the calcination temperature is 700 °C, an optimal microwave absorption (MA) property is obtained for sample S700 at 25 wt% filler loading ratio. Herein, the values of the minimum reflection loss (RLmin) and the effective absorption bandwidth (EAB) attain −52.73 dB at 2.51 mm and 6.16 GHz at 2.31 mm, respectively. Meanwhile, when the filler loading increases to 30 wt%, RLmin and EAB for sample S600 achieve −60.02 dB at 1.59 mm and 5.76 GHz at 1.90 mm, respectively. In fact, the superior electromagnetic parameters are achieved under the comprehensive action of the specific morphology, microstructure and graphitization. Further, the applicable filler loading ratio, appropriate impedance matching and moderate magnetic/dielectric loss of the absorbers are the advantageous factors to improve their MA behavior. Our work offers an effective strategy to synthesize MOF-derived magnetoelectric composites with controllable MA performance, and the as-obtained composites can serve as the ideal microwave absorbers at 2 ∼ 18 GHz frequency range.

Synthesis and characterization of Ti0.9Ir0.1O2-activated carbon composite as a promising support for catalysts in electrochemical energy conversion

Constructing robust support plays a key role in governing the overall catalytic efficiency of metal-based catalysts for electrochemical reactions in sustainable energy-related conversion systems. We herein use a solvothermal method to assemble Ti0.9Ir0.1O2-Activated C composites, exhibiting high surface area and electrical conductivity compared to the pure TiO2 material. The material characterisations and electrochemical behaviours of the as-obtained composites are systemically studied by XRD, FE-SEM-EDX mapping, FT-IR, XPS, BET, four-point technique, cyclic voltammetry, etc Notably, the effect of composition on the physical and electrochemical properties of the as-made composites is also explored, which indicated the significant improvement in surface area and electrical conductivity with increasing carbon content, while a reverse trend is observed in the electrochemical durability. Among all studied composites, the Ti0.9Ir0.1O2-Activated C (50:50 wt%) composite can be a suitable support for metal-based catalysts due to its balance in physical properties (electrical conductivity of 1.5 S cm−1 and surface area of 152.12 m2 g−1) and electrochemical corrosion resistance (high durability after 2000-cycling ADT). This study can open up an efficient strategy to enhance the catalytic performance of electrochemical processes.

3D-Printed Polyamide 12/Styrene-Acrylic Copolymer-Boron Nitride (PA12/SA-BN) Composite with Macro and Micro Double Anisotropic Thermally Conductive Structures.

Anisotropic thermally conductive composites are very critical for precise thermal management of electronic devices. In this work, in order to prepare a composite with significant anisotropic thermal conductivity, polyamide 12/styrene-acrylic copolymer-boron nitride (PA12/SA-BN) composites with macro and micro double anisotropic structures were fabricated successfully using 3D printing and micro-shear methods. The morphologies and thermally conductive properties of composites were systematically characterized via SEM, XRD, and the laser flash method. Experimental results indicate that the through-plane thermal conductivity of the composite is 4.2 W/(m·K) with only 21.4 wt% BN, which is five times higher than that of the composite with randomly oriented BN. Simulation results show that the macro-anisotropic structure of the composite (caused by the selective distribution of BN) as well as the micro-anisotropic structure (caused by the orientation structure of BN) both play critical roles in spreading heat along the specified direction. Therefore, as-obtained composites with double anisotropic structures possess great potential for the application inefficient and controllable thermal management in various fields.

Fabrication of SiCw/SiC–Si–Y composites and their resistance to water-oxygen corrosion at 1500 °C

The thermos-structural materials with high strength and high temperature water-oxygen corrosion resistance are urgently needed in aero-space fields. SiC whisker reinforced SiC matrix (SiCw/SiC) composites are the ideal candidate materials for their excellent mechanical properties and thermostability. However, the poor resistance to water-oxygen corrosion ability of SiC matrix limits their further application. In this work, a novel SiCw/SiC–Si–Y composites were first prepared by infiltrating silicon-yttrium (Si–Y) alloy into SiCw/C preform via reactive melt infiltration method. The as-obtained composites not only show the excellent mechanical properties (σF = 363 MPa, KⅠC = 9.14 MPa m1/2), and more importantly after water-oxygen corrosion of 20 h at such temperature as high as 1500 °C, the strength and toughness retention of the composites can reach 106.1% and 103.6%, respectively. The SiCw/SiC–Si–Y composites developed in this paper have a great potential as a new high-performance thermos-structural material for aero-space applications.

Heteropolyacid-loaded MOF-derived mesoporous zirconia catalyst for chemical degradation of rhodamine B

Abstract In this article, silicotungstic acid (STA)-loaded metal–organic framework (MOF)-derived composites (C-STA@ZrO2) were successfully synthesized by simple strategies. X-ray diffraction, Fourier transform infrared, scanning electron microscopy, energy-dispersive X-ray, N2 physisorption, UV-vis diffuse reflection spectroscopy, and X-ray photoelectron spectroscopy techniques were used to characterize the as-obtained composites. Intriguingly, C-STA@ZrO2 exhibits excellent photocatalytic performance, and rhodamine B (RhB) (40 mg·L−1) in water can be degraded to 93.9% after 120 min of irradiation. Moreover, various catalysts, catalyst dosage, and dye concentrations on RhB degradation were evaluated. Besides, the reusability of C-STA@ZrO2 was also investigated. This work may provide a new and significant guideline for exploring excellent performance of MOF-derived hybrid material for wastewater purification.

SiO2/MOFs-based synergistic flame retardants provide enhanced fire safety for epoxy resins

To improve the inherent flammability of epoxy resin (EP), a new synergistic flame retardant (SiO2/PANI/ZIF-67) with silica, polyaniline (PANI) and zeolitic imidazolate framework-67 (ZIF-67) was synthesized successfully via an electrostatic interaction and chemical bonding technique. With the addition of 6% SiO2/PANI/ZIF-67, the limiting oxygen index (LOI) of as-obtained EP composite reaches up to 28.0%. The total heat release (THR), total smoke production (TSP) and total CO production (TCOP) of the composite are significantly decreased to 44.06%, 45.05% and 44.05% respectively. The synergistic role of SiO2, PANI and ZIF-67 induces formation of a dense SiO2-C layer, which greatly reduces emission of smoke gas and heat, and subsequently increases the fire safety of EP. Furthermore, the presence of organic-inorganic hybrid ZIF-67 on surface of flame retardant leads to its strong interface adhesion and well dispersibility in EP matrix. This work provides a simple route for designing and preparation of SiO2/MOFs-based synergistic flame retardants, which is of great significance to improve fire safety of epoxy resins.

Thermal decomposition behavior and kinetic study of nitrocellulose in presence of ternary nanothermites with different oxidizers

Nanothermites have recently attracted a great deal of interest in both military and civilian domains owing to their capability of igniting or exploding and releasing a significant quantity of heat via a redox reaction. In this study, three ternary nanothermites, which contain MgAl alloy as fuel and different metal oxides (MXOY = CuO, NiO, TiO2) as oxidizers, were prepared through the arrested reactive milling technique. These metastable intermolecular composites were introduced to nitrocellulose (NC), using a fast solution drying technique, to assess their catalytic behavior. The as-obtained energetic composites, namely, NC/MgAl-MXOY, were scrutinized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), powder X-ray diffraction (XRD), and differential scanning calorimetry (DSC). The ignition delay time of NC/MgAl-MXOY composite films was also determined, and the results revealed the positive effect of the introduction of nanothermite through the decrease of its value compared to pure NC. Using the isoconversional kinetic analysis, the Arrhenius parameters associated with the thermal decomposition of the as-obtained NC/MgAl-MXOY energetic composites films were also evaluated. The findings indicated that the choice of the oxidizer within the nanothermite composition significantly influences the decomposition behavior of the NC/MgAl-MXOY energetic composites. Based on the obtained results, the MgAl-CuO nanothermite provides better performance than MgAl-NiO and MgAl-TiO2 nanoparticles.

Insights into the high performance of Co–Mn oxide supported by carbon fiber frameworks for ciprofloxacin oxidation process

In this study, a manganese-cobalt bimetalli oxide composite material was innovatively prepared by the chemical co-precipitation method at low temperatures, in which activated carbon fibers (ACFs) as an organic carbon skeleton carrier could strengthen the stability of nanomaterials. The as-obtained composites were promising with rich chemical bonds, high redox properties, appreciable adsorption capacity, remarkable catalytic performance, and favorable stability. Experimental results showed that within 120 min, the composites could effectively degrade more than 90% of ciprofloxacin (CIP) by activating peroxomonosulfate (PMS). The electron transfer between the bimetal oxides improved the catalytic activation efficiency. The mechanism study suggested that SO4·−, ·OH, O2·−, and 1O2 are the main active substances, and combined with LSV and multimeter, it was found that there was electron transfer in the reaction system and Co3O4–Mn3O4@ACFs had the strongest electron transfer capability. In addition, the synthesized Co3O4–Mn3O4@ACFs have the potential for a wide range of applications due to the advantages of efficient PMS utilization efficiency and easy recovery properties. This work provided another perspective on the degradation of fluoroquinolone antibiotics in aqueous matrices in persulfate-based AOPs.

Preparation, Characterization, and Wound Healing Assessment of Curcumin-Loaded M-MOF (M = Cu, Zn)@Polycaprolactone Nanocomposite Sponges.

The fabrication of multifunctional scaffolds has attracted much attention in biological fields. In this research, some novel composites of Cu(II) or Zn(II) metal-organic framework (M-MOF) and polycaprolactone (PCL), M-MOF@PCL, have been fabricated as multifunctional scaffolds for application in the tissue engineering (TE) field. The porous three-dimensional sponges were prepared by the salt leaching method. Then, the M-MOF@PCL composite sponges have been prepared by in situ synthesis of M-MOF in the presence of the as-obtained PCL sponge to gain a new compound with proper features for biological applications. Finally, curcumin was attached to the M-MOF@PCL as a bioactive compound that can act as a wound-healing agent, anti-oxidant, and anti-inflammatory. The presence of the M-MOF in final composites was investigated by different methods such as FTIR (Fourier-transform infrared), XRD (X-ray diffraction), SEM (scanning electron microscope), EDS (energy-dispersive X-ray spectroscopy), and TEM (transmission electron microscope). SEM images confirmed the porous structure of the as-obtained composites. According to the EDS and TEM images, M-MOFs were uniformly incorporated throughout the PCL sponges. The water sorption capacities of the blank PCL, Cu-MOF@PCL, and Zn-MOF@PCL were determined as 56%, 155%, and 119%, respectively. In vivo investigation on a third-degree burn model in adult male Wistar rats exhibited an accelerated wound healing for Cu-MOF@PCL compared to with Zn-MOF@PCL and the control group.

Fabrication of a novel bioactive chitosan based biocomposite from Opuntia ficus-indica fruit gum and evaluation of anticancer activity in bone MG63 cancer and L929 normal cell lines

In this paper, a novel bioactive Chitosan-Lignin/n-Hydroxyapatite/Opuntia ficus-indica -Fruit gum (Cs-Lg/n-Hap/OFI-Fg) biocomposite was fabricated. The as-obtained biocomposite properties are analyzed by optical and structural investigation. The biological properties like antibacterial, antioxidant, and anticancer ability were evaluated for the biocomposites. The FT-IR spectrum result shows the biocomposites possess significant intermolecular interaction with biomolecules. The powder XRD result indicated the as-obtained Cs-Lg/n-Hap/OFI-Fg biocomposites are crystalline in nature. The microhardness test shows the addition of fruit gum increases the mechanical strength of the biocomposite. The thermal stabilities of the as-obtained Cs-Lg/n-Hap/OFI-Fg biocomposite were higher than to Cs-Lg/n-Hap composite as revealed by TGA analysis. The SEM images show an addition of fruit gum leads to the formation of spherical-shaped discrete particle morphology evidenced by TEM analysis. The antioxidant and antibacterial activity of bioactive biocomposite shows better activity due to the presence of numerous biomolecules. The MTT assay result revealed significant activity in as-obtained Cs-Lg/n-Hap/OFI-Fg biocomposite compared to Cs-Lg/n-Hap composite against MG63 bone cells and L929 cells due to the active biomolecules extant in fruit gum. The anticancer results revealed that 5 µg/ml concentration biocomposite is a significant role against bone cancer cells which proves that the as-obtained composites could be more valuable for the treatment of bone deficiency.

Synthesis, characterization and photocatalytic properties of In2.77S4/Ti3C2 composites.

Recently, the problem of water pollution, caused by antibiotics, is becoming more and more serious. Photocatalysis is one of the promising technologies for removing antibiotics from water. Herein, the In2.77S4/Ti3C2 composites were prepared by an in-situ hydrothermal growth method for photocatalytic degradation of tetracycline (TC). The as-developed composites were characterized by various methods. The UV-Vis DRS spectra reveals that the introduction of Ti3C2 makes the bandgap of the as-prepared composites smaller and the visible light absorption ability improved. The photocatalytic degradation efficiency of the as-prepared composite is enhanced under visible light illumination. It is shown as first increasing and then decreasing with increasing the content of Ti3C2 in the composite and reaches to the maximum of 89.3% in 90min, which is higher than 75.1% of In2.77S4 and 6.7% of Ti3C2. The reason of improvement is the interface between In2.77S4 and Ti3C2 is tightly combined to form a heterojunction. Moreover, the photocurrent intensity of the as-obtained composite is improved, while its Nyquist arc radius is decreased. In addition, holes are the main active species and ·OH and ·O2 - play an auxiliary role during the degradation of TC.

Efficient visible-light-photocatalytic sterilization by novel Z-scheme MXene/TiO2/Bi2S3

Photocatalytic sterilization has been recently realized as a competitive strategy for effective water purification just using sunlight, for which the new photocatalytic materials play the key role. In this study, a novel Z-scheme heterojunction material MXene/TiO2/Bi2S3 was proposed, where TiO2 nanoparticles and Bi2S3 microspheres were uniformly distributed on the MXene nanosheets through facile hydrothermal oxidation and ultrasonic dispersion. With this Z-scheme heterojunction MXene/TiO2/Bi2S3, effective and quick sterilization of both Gram-negative bacteria and positive bacteria in only 120 min was realized. Especially, the apparent reaction constant for S. aureus reached 0.01659 min−1, substantially higher than MXene and other related materials in literature. This could be ascribed to the narrow band gap (1.04 eV), the wide range of light absorption range (420 nm), and the low impedance of the as-obtained composite, facilitating the transfer and separation of photo-generated charges, which was also validated through the first-order kinetic model and DFT simulation calculations. Thus, the reactive species produced by photocatalysis effectively disrupted the defense action of the bacteria by damaging bacterial membrane structure, and reducing enzyme activity as well as cellular metabolism. This efficient and low-cost material for water disinfection has a great potential for practical applications in the future.