Composite Nanosheets Research Articles

Layered CoS@NC in situ loaded onto Ti3C2Tx MXene as an efficient lithium-ion battery anode.

Due to its large capacity and relatively high conductivity, cobalt sulfide has been considered an excellent electrode material for lithium-ion batteries, but its extreme volume change during charging and discharging and lower conductivity than graphite limits its development. In this work, composite nanosheets of MXene and N-doped carbon-confined cobalt sulfide nanosheets (CoS@NC/MXene) were synthesized by growing the Co metal-organic framework of ZIF-67 onto MXene sheets, followed by sulfidation treatment. Different from normal ZIF-67 generally prepared in methanol, this work fabricates ZIF-67 in aqueous solution, which induces ZIF-67 to undergo some degree of hydrolysis and form more dispersed Co layered hydroxides mounted onto MXene. Also, the MXene incorporation imparts better water stability to ZIF-67(Co) and helps maintain its morphology during the sulfidation. CoS@NC/MXene has a conductive network supported by MXene and enhanced by NC, as well as a 3D hierarchical porous structure offered by the rational combination of its components. These favorable characteristics allow CoS@NC/MXene to deliver a capacity of 691 mA h g-1 at 200 mA g-1 in the 100th cycle and retain the specific capacity of 382 mA h g-1 at a higher current density of 8000 mA g-1.

Enhanced electromagnetic wave attenuation performance of hierarchical Fe3O4/N-doped carbon nanosheets by heterointerface engineering

The dielectric-magnetic composites with a unique structure are regarded as promising materials for addressing the issue of electromagnetic wave pollution. Herein, a series of hierarchical Fe3O4/N-doped carbon nanosheets (Fe3O4/HNCS) composites with adjustable electromagnetic wave attenuation (EMWA) properties were successfully fabricated by adjusting the proportion of iron source and carbon using a simple combination of molten salt and solvothermal methods. Among all the composites, the Fe3O4/HNCS-0.25 exhibits the strongest reflection loss (RL) value of − 52.08 dB with an ultra-thin thickness of 1.4 mm, corresponding to an effective absorption bandwidth (EAB) of 4.16 GHz. Furthermore, the Fe3O4/HNCS-0.20 achieves a maximum EAB value of 4.4 GHz, obtained at a thickness of 1.4 mm. The superior EMWA performances originate from excellent impedance matching, synergy between dielectric and magnetic loss, and unique hierarchical structure. This study presents a straightforward and environmentally friendly method for fabricating high-performance dielectric-magnetic EMWA materials with an ultra-thin matching thickness.

Mn2+-Triggered Swing-Arm Robot Strategy Using Anemone-Like Thi@AuPd@Cu-MOFs as Signaling Probes for the Detection of T-2 Toxin.

Herein, we synthesized anemone-like copper-based metal-organic frameworks (MOFs) loaded with gold-palladium nanoparticles (AuPd@Cu-MOFs) and polyethylenimine-reduced graphene oxide/gold-silver nanosheet composites (PEI-rGO/AuAg NSs) for the first time to construct the sensor and to detect T-2 toxin (T-2) using triple helix molecular switch (THMS) and signal amplification by swing-arm robot. The aptasensor used PEI-rGO/hexagonal AuAg NSs as the electrode modification materials and anemone-like AuPd@Cu-MOFs as the signal materials. The prepared PEI-rGO/hexagonal AuAg NSs had a large specific surface area, excellent electrical conductivity, and good stability, which successfully improved the electrochemical performance of the sensors. The AuPd@Cu-MOFs with high porosity provided a great deal of attachment sites for the signaling molecule thionine (Thi), thereby increasing the signal response. The aptasensor developed in this study demonstrated a remarkable detection limit of 0.054 fg mL-1 under optimized conditions. Furthermore, the successful detection of T-2 in real samples was achieved using the fabricated sensor. The simplicity of the THMS-based method, which entails modifying the aptamer sequence, allows for easy adaptation to different target analytes. Thus, the sensor holds immense potential for applications in quality supervision and food safety.

P/S-g-C3N4 nanosheet composites with enhanced photocatalytic water splitting and dye degradation

The band gap and photo- and electro-chemical activities of graphic carbon nitride (g-C3N4) depended strongly on their components. In this paper, P-g-C3N4/S-g-C3N4 (PCN/SCN) and S-g-C3N4/P-g-C3N4 (SCN/PCN) composite nanosheets heterostructures were created using P-doped and S-doped g-C3N4 nanosheets as seeds to study the effect of compositions on photo- and electro-chemical properties. Thermal polymerization temperature and the ratios of S- and P-doped g-C3N4 components were adjusted to get optimized conditions. The photo-degradation kinetics of Rhodamine B (Rh B) and photocatalytic H2 generation were used to discuss the relationship of photocatalytic performance and composition of photocatalysts. The degradation of Rh B in visible light region was finished using sample 600MCNS@ 720 DCNP15% within 15 min with a degradation rate constant of 0.197, which was 2.3 and 3.9 times compared with S- and P-doped g-C3N4 nanosheets, respectively. Namely, the H2 generation rate of sample 600MCNS@ 720 DCNP15% was 1851.9 µmolg−1h−1, which is 6.6 and 5.9 times higher than those of S- and P-doped g-C3N4 nanosheets, respectively. Interestingly, these P/S-g-C3N4 composite heterojunctions revealed improved electro-chemical performance. In the case of a current density of 1 mA cm−2, the overpotential of ample 600MCNP@ 720 DCNS20% was 333 mV and a Tafel slope was 155.33 mV dec−1 in KOH solutions. This result supplied an efficient approach to improve the photocatalytic performance of g-C3N4 based materials.

Hydrothermal synthesis of zinc-cobalt binary hydroxide / reduced graphene oxide composite nanosheets as electrode materials with surface redox pseudocapacitive behaviour

Binary metal hydroxides have grabbed the attention of researchers in energy storage field owing to their better electrochemical properties compared to that of monometallic counterparts and metal oxides. Being an eco-friendly, abundant, and cost effective metal, Zinc has been chosen to form binary hydroxide with cobalt which can show multiple valence states during electrochemical reactions. Zinc-Cobalt binary hydroxide (ZCH) nanosheets and its nanocomposite with reduced Graphene Oxide (ZCH-rGO) were synthesized through a simple hydrothermal method. Electrochemical properties of the prepared samples were analyzed by means of cyclic voltammograms, chronopotentiograms, and Nyquist plots. ZCH-rGO nanocomposite exhibited a high specific capacitance of ⁓756.8 F/g whilst ZCH nanosheets showed relatively less specific capacitance of ⁓594.6 F/g at 1 A/g. The electrochemical performance of ZCH-rGO nanocomposite was assessed using a two-electrode system from which the energy density was found to be 10.6 Wh/kg. This electrochemical setup of ZCH-rGO nanosheets displayed a capacitance retention of 126.6 % after 2000 charge-discharge cycles. Addition of rGO changed the primary electrochemical behaviour of ZCH from battery-type to capacitive-type thereby producing an electrode material with surface redox pseudocapacitive properties.

Facile synthesis of ionic liquid mobilized ZnO@Ti3C2Tx composite nanosheets for high charged transfer, sensitive and selective electrochemical detection of 5-flurouracil in waste water and urine samples

Controlling and monitoring the concentration of anticancer drugs in physiological fluids and water bodies are crucial for successful cancer treatment and environmental considerations. However, the development of electrochemical-based sensors having high charge transfer rate, high conductivity, sensitivity and selectivity for anticancer drugs (ACDs) have been limited research due to their poor oxidation–reduction behaviour and complex structures. To address this issue, we pursuit a simple and efficient synthesis route of zinc nanowires (ZnO NWs) decorated on MXene (Ti3C2Tx) nanosheets and utilized for the electrochemical detection of antimetabolite drug namely, 5-fluorouracil (5-FU). We enhance the charge transfer between two nanostructures by incorporating an ionic liquid (ILs). Detailed spectroscopic analysis demonstrates the interaction between ZnO and MXene, which is further improved by the addition of ILs through metal–oxygen bonds. XRD patterns also indicated an intensity reduction and shifting of the MXene’s (002) peak which supporting the spectroscopic results. Moreover, the results confirm that ILs enhance the interfacial connectivity between ZnO NWs and MXene nanosheets through electrostatic interactions, improving the charge transfer rate, sensing capability, and signal intensity for anticancer drug detection. The optimized ILs_ZnO@MX composite exhibits a 10-fold lower limit of detection for 5-FU (0.03 µM) compared to bare ZnO@MX.

Enhanced selectivity and charge transfer over highly dispersed Cd0.2Zn0.8S/meta-kaolinite catalysts for CO2 photoreduction

In this work, a novel hybrid photocatalyst consisting of Cd0.2Zn0.8S grown on a defect-rich meta-kaolinite nanosheet (CZS/MK) composite was investigated for the photoreduction of CO2 to CO in the presence of simulated sunlight with high selectivity. CZS/MK displayed a CO yield of 21.3 µmol g−1h−1 with a remarkable selectivity of 97.4 % without any co-catalyst and sacrificial reagent. The addition of MK to the catalyst altered CZS hydrophilicity and improved CO selectivity. Moreover, kaolinite is relatively inexpensive, and the defects in MK can optimize pore size distribution and structure of Cd0.2Zn0.8S, resulting in improved dispersion and a higher quantity of exposed active sites on the composite material. Experimental investigations combined with DFT calculations illustrated that the adsorption configuration involving the introduction of kaolinite was more favorable for CO2 activation, which ultimately decreased the formation barrier of key intermediate *COOH. In situ Fourier transform-infrared analysis indicated that Cd0.2Zn0.8S/MK tended to produce vital *COOH intermediates, thereby achieving higher CO conversion efficiency. This study provides novel insights into the utilization of kaolinite-based catalysts for enhancing CO2 photoreduction.

Defect Engineering of 2D Copper Tin Composite Nanosheets Realizing Promoted Electrosynthesis Performance of Hydrogen Peroxide.

The transformation of the two-electron oxygen reduction reaction (2e-ORR) to produce hydrogen peroxide (H2 O2 ) is a promising green synthesis approach that can replace the high-energy consumption anthraquinone process. However, designing and fabricating low-cost, non-precious metal electrocatalysts for 2e-ORR remains a challenge. In this study, a method of combining complexation precipitation and thermal treatment to synthesize 2D copper-tin composite nanosheets to serve as the 2e-ORR electrocatalysts is utilized, achieving a high H2 O2 selectivity of 92.8% in 0.1m KOH, and a bulk H2 O2 electrosynthesis yield of 1436 mmol·gcat -1 ·h-1 using a flow cell device. Remarkably, the H2 O2 selectivity of this catalyst decreases by only 0.5% after 10,000 cyclic voltammetry (CV) cycles. In addition, it demonstrates that the same catalyst can achieve 97% removal of the organic pollutant methyl blue in an aqueous system solution within 1h using the on-site degradation technology. A reasonable control of defect concentration on the 2D copper-tin composite nanosheets that can effectively improve the electrocatalytic performance is found. Density functional theory calculations confirm that the surface of the 2D copper-tin composite nanosheets is conducive to the adsorption of the key intermediate OOH* , highlighting its excellent electrocatalytic performance for ORR with high H2 O2 selectivity.

Using the inherent elements in yeast biomass to produce Ni2P/N-doped biocarbon composites for efficient hexavalent chromium reduction.

The heterogeneous catalytic reduction of Cr(VI) to Cr(III) is an effective strategy for aqueous Cr(VI) contamination abatement, which requires the development of highly efficient, low-cost, and recyclable catalysts. Herein, Ni2P/N-doped biocarbon composites (Ni2P/N-BC) were fabricated through an anoxic pyrolysis process using NaCl and KCl as activators. A precursor of yeast biomass provided the essential C, N, and P elements for Ni2P/N-BC formation. When adopted for Cr(VI) reduction in the presence of oxalic acid as a reductant, the fabricated Ni2P/N-BC performed superior catalytic activity with a 100% Cr(VI) reduction efficiency within 10 min (Ni2P/N-BC-5 = 0.2 g L-1, oxalic acid = 0.4 g L-1, Cr(VI) = 20 mg L-1). Typical affecting parameters, e.g., catalyst dosage, oxalic acid loading, reaction temperature, initial solution pH, and water matrix, were investigated. Ni2P/N-BC exhibited good applicability in a broad pH range from 3.0 to 9.0 and in actual aquatic systems. Cr(VI) reduction efficiency remained 92.7% after five recycle runs. Such promising catalytic activity may originate from the well-crystallized Ni2P, N-doped biocarbon framework and high specific surface area of the materials. Preliminary reaction mechanism analysis indicated that the favorable charge state of Ni2P, fast hydrogen transfer, affinity of oxalic acid to Cr(VI), and inherent electron transfer in the biocarbon matrix contributed to effective Cr(VI) reduction. This work not only provides a facile and low-cost strategy to construct Ni2P/N-doped biocarbon nanosheet composite using environmentally benign biomass but also brings new insights for the remediation of Cr(VI) contamination.

Preparation of amphiphilic Janus nanosheets based on thermally expandable microspheres and evaluation of their physical and chemical properties

Janus nanosheets can reduce the interfacial tension of oil and water and are of great significance for improving the recovery efficiency of remaining oil. A novel strategy for preparing amphiphilic Janus nanosheets is presented in this paper. Trialkoxysilane is adsorbed on the surface of thermally expandable microspheres (TEMS), and Janus spheres (TEMS@SiO2) are obtained by sol-gel treatment. Dodecyltrimethoxysilane (DTES) is used to modify TEMS@SiO2, which is combined with the thermal expansion of TEMS and the breaking of the outer shell of Janus spheres to prepare amino/alkyl composite silicon-based amphiphilic Janus nanosheets (ASAJN). Characterization of ASAJN is carried out via FTIR, TG, SEM, TEM, and contact angle tester, with the results showing that ASAJN boasts amphiphilicity and two-sidedness, and a sheet structure with a thickness of 210 nm. The stability, wettability evaluation, emulsification properties, and interface properties of ASAJN nanofluids have been evaluated, with the results showing that ASAJN nanofluids boast good stability without delamination after 30 days. ASAJN nanofluid can convert oil-wet core slices into water-wettable ones. ASAJN nanofluid manifests excellent emulsification, with the 240-hour emulsification index of ASAJN nanofluid and silica fluid respectively at0.40 and 0.021 under ultra-low concentration (1000 mg/L). ASAJN is obviously able to reduce oil–water interfacial tension. At 1000 mg/L (60 ℃) concentration, the oil-water interfacial tension is reduced to 2.6 mN/m, while that of nano-silica at the same concentration is 15.1 mN/m. ASAJN flooding can significantly improve the recovery efficiency of low-permeability reservoirs, increasing the recovery efficiency by 32.8 % at a permeability of 7.5 × 10-3 μm2.

One-step synthesis of SnS2/SnO2 nanoflowers for high-performance hybrid supercapacitors

In this work, the flower-like SnS2/SnO2 (nanoflowers, NFs) composite and SnS2 nanosheets (NSs) were respectively prepared in the presence of different amount of thiourea through a facile one-step hydrothermal method. These SnS2/SnO2 NFs and SnS2 NSs exhibited the typical battery-like electrochemical response. At the current load of 1 A g−1, the specific capacity was determined to be 304.6 C g−1 for NFs composite and 244.1 C g−1 for NSs. In order to evaluate the potential of practical application in electrochemical energy storage, a hybrid supercapacitor (HSC) was assembled with these SnS2-based electrode materials as cathode and activated carbon (AC) as anode, and the HSC could be operated over a maximum voltage of 1.6 V. The SnS2/SnO2 NFs//AC HSC delivered an energy density of 33.4 W h kg−1 at the power density of 993.2 W kg−1. In contrast, the SnS2 NSs//AC HSC exhibited 27.4 W h kg−1 at 929.9 W kg−1. Both HSCs showed good cycling performance during the continuous 5000 GCD cycles without any capacity decay. This impressive electrochemical property proves that the SnS2/SnO2 NFs composite can serve as promising electrode material for the assembly of advanced HSC device. In addition, the present synthetic strategy can be extended to the synthesis of other transition metal sulfides (TMSs)-based electrode materials with controllable shapes and excellent electrochemical response.

Flexible and disposable electrodes based on SnO2 nanoparticle/Nb2CTx nanosheet composites for selective and ultrasensitive detection of propofol

A disposable electrochemical sensor for the detection of the propofol (PPF), an anesthetic drug, has been developed using a composite of SnO2 nanoparticle and Nb2CTx MXene (SnO2/Nb2CTx). The SnO2/Nb2CTx is modified on a flexible carbon cloth for highly sensitive and selective electrochemical detection of PPF. The ratio of SnO2 in the composite was optimized to get enhanced sensor response to cover the analyte range from 1 μM to 300 μM with a limit of detection of 0.24 µM. The developed sensor possesses the requisite sensor parameters viz. selectivity, sensitivity, reproducibility, and storage stability. Based on the flexibility analysis, it is confirmed that the developed sensor works for the detection of PPF on a flexible platform as well. The real sample analysis done by spiking PPF in human artificial serum further proves that the developed PPF sensor can effectively detect PPF in serum samples. Over all, the developed sensor improves patient safety by ensuring that they receive the appropriate amount of medication at the right time minimizing the risk of adverse effects associated with over-sedation or under-sedation.

Molten salts synthesis of Mo2C nanoflake and its composites for enhanced lithium-storage performance

The rational design of negative and positive materials to make them have satisfactory specific capacity and rate capability is an effective strategy to enhance the electrochemical properties of Lithium-ion hybrid capacitors (LIHCs). Herein, hierarchical MC-X (X = 0, 1, 2, 3) nanosheet composites were prepared by salt template-assisted solid-state synthesis strategy. Among them, Mo2C nanosheets are more dispersed on the amorphous carbon, and the close contact between them makes molybdenum carbide have enough buffer space during the intercalation and deintercalation of Li+, and makes MC-2 have a desirable specific surface area (SSA) of 341.1 m2/g. Electrochemical tests showed that the specific capacity of Mo2C remained at 313 mAh/g after 1000 cycles at 0.1 A/g, respectively. Meanwhile, the badam shell biochar (B) was prepared by KOH activation. The best sample (B-3) exhibited a high SSA of 3729.969 m2/g and high specific capacities of 265.6 mAh/g at 0.1 A/g, respectively. Furthermore, the constructed MC-2//B-3 LIHC exhibits high power density (4.68 kW kg−1), energy density (81.19 Wh kg−1), and excellent long-cycle stability. Therefore, the key to building a desirable property LIHC is to give consideration to the electrochemical performance between the positive and negative electrodes.

Photocatalytic removal of organic pollutants by SiO2 modified BiOCl nanosheets with abundant oxygen vacancies

In this demonstration, SiO2/BiOCl composites were fabricated by loading SiO2 nanoparticles onto the surface of BiOCl nanosheets through a conventional hydrothermal approach. SiO2/BiOCl photocatalysts were studied by specific surface area analysis, X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), UV–Vis diffuse reflection spectroscopy (UV–Vis DRS) and electron spin resonance (ESR) techniques. In light of the rich pore structures of BiOCl modified by SiO2, the photogenerated carriers separation efficiency of SiO2/BiOCl is significantly improved. Therefore, SiO2/BiOCl composite nanosheets show high efficiency towards degradation of perfluorooctanoic acid (PFOA) and rhodamine B (RhB), and the composites display exceptional stability. In comparison to the pure BiOCl, photocatalytic degradation activity of 4.4 % SiO2/BiOCl (mass ratio of SiO2/Bi(NO3)3·5H2O is 4.4 %) for RhB and PFOA increases by 100 % and 50 %, respectively. The result from the radical capture experiments suggests that holes (h+) and superoxide radicals (·O2–) play a crucial role as the primary active species in degradation of organic pollutants. The enhanced photocatalytic efficiency of the SiO2/BiOCl composites can be primarily ascribed to the construction of numerous oxygen vacancies (OVs), which effectively promote the adsorption of organic pollutants, boost light responsiveness, and expedite the separation of photoinduced e-/h+ pairs.

In-situ embedding of carbon dots in boron nitride for enhancing phosphor stability and fluorescent film heat dissipation

The aggregation-induced quenching effect and poor thermal stability issues of carbon dots (CDs) limit their further development in the solid-state lighting and display field. In this work, a red carbon dot/boron nitride nanosheet (rCDs/BNNS) composite was synthesized using boron nitride as a carrier by in-situ embedding of rCDs. Thanks to the uniform dispersion of rCDs and the restraint of BNNS, the prepared rCDs/BNNS composite has excellent fluorescence stability and thermal stability. rCDs/BNNS composites as fluorescent markers can be used to detect potential fingerprints on various surfaces. Furthermore, rCDs/BNNS were dispersed into polyvinyl alcohol (PVA) polymers to prepare rCDs/BNNS/PVA flexible luminescent films. In addition to the excellent stability inherited from rCDs/BNNS, the thin film also exhibits high heat dissipation by reason of the establishment of a heat transfer channel in the PVA by rCDs/BNNS. Moreover, thin films can still maintain original fluorescence after undergoing hundreds or thousands of bends, while possessing sufficient tensile strength. This study provides a facile pathway for the preparation of highly stable CDs luminescent materials, and has a promising application in the forensic identification and flexible luminescent devices' thermal management fields.

Synthesis and characterization of enhanced visible light-driven C-doped ZnO-2D GO/g-C3N4 heterojunction photocatalyst

Well-designed 2D graphene oxide-modified polymeric graphitic carbon nitride composite nanosheets (GO/g-C3N4) as desirable sensitizers and catalytic substrates for optimising the visible light-driven photocatalytic performance of ZnO-based photocatalysts have been investigated. Herein, 2D GO/g-C3N4 composite nanosheets are first developed by ultrasonic and hydrothermal methods, and then coupled with ZnO nanoparticles to prepare a series of ternary GO/g-C3N4-ZnO heterojunction composites with vary GO loading concentrations. Characterization of the photocatalysts was carried out by SEM, TEM, XPS, XRD, DRS, photoluminescence (PL) spectroscopy; evaluation of the visible light photocatalytic activity was performed by degrading an aqueous methylene blue (MB) solution. XPS studies showed that the formation of a ZnC bond in 15 % GO/g-C3N4-ZnO is due to the replacement of oxygen by carbon, indicating the construction of a hybrid heterojunction composed of C-doped ZnO and visible light sensitive GO/g-C3N4 composite nanosheets. The photodegradation performance of 15 % GO/g-C3N4-ZnO is 5.3, 2.9, and 2.2 times higher than that of pure ZnO, g-C3N4, and g-C3N4-ZnO, respectively. Due to the increase of GO loading in GO/g-C3N4 composite nanosheets, some characteristics of efficient visible light photocatalysis, such as a wider light absorption range, fluorescence quenching in the PL spectrum, excellent optical response in photocurrent measurement, and good stability，were confirmed and can be attributed to the electronic interaction between heterostructures and the effective transfer of photogenerated electrons in these ternary nanocomposites. This work may provide a new promising pathway for the construction of easily prepared 2D GO/g-C3N4 hybrid-modified nanocomposites, which is a hopeful material for wastewater control.

Tuning the Ferroelectric Response of Sandwich-Structured Nanocomposites with the Coordination of Ba0.6Sr0.4TiO3 Nanoparticles and Boron Nitride Nanosheets to Achieve Excellent Discharge Energy Density and Efficiency.

With the rapid development of new electronic products and sustainable energy systems, there is an increasing demand for electrical energy storage devices such as electrostatic capacitors. In order to comprehensively improve the dielectric, insulating, and energy storage properties of PVDF-based composites, sandwich-structured composites were prepared by layer-by-layer solution casting. The outer layers of the sandwich structure composite are both PVDF/boron nitride nanosheet composites, and the middle layer is a PVDF/Ba0.6Sr0.4TiO3 nanoparticles composite. The structural and electrical properties of the sandwich-structured composites were characterized and analyzed. The results show that when the volume percentage of Ba0.6Sr0.4TiO3 nanoparticles in the middle layer of the sandwich structure composite is 1 vol.%, the dielectric properties are significantly improved. Its dielectric constant is 8.99 at 10 kHz, the dielectric loss factor is 0.025, and it has better insulating properties and resistance to electrical breakdown. Benefiting from the high breakdown electric field strength and the large maximum electrical displacement, the sandwich-structured composites with 1 vol.% and Ba0.6Sr0.4TiO3 nanoparticles in the middle layer show a superior discharge energy density of 8.9 J/cm3, and excellent charge and discharge energy efficiency of 76%. The sandwich structure composite achieves the goal of simultaneous improvement in breakdown electric field strength and dielectric constant.

Design of Bi4O5Br2/g‐C3N4 heterojunction for efficient photocatalytic removal of persistent organic pollutants from water

AbstractDyes and antibiotics as typical persistent organic pollutants (POPs) are widely present in the environment, but can hardly be removed completely by traditional water treatment methods. Here, we designed Bi4O5Br2/g‐C3N4 composite nanosheets for efficient photocatalytic removal of POPs in water. The Bi4O5Br2/g‐C3N4 composite with a heterojunction structure exhibited high adsorption and photocatalytic activity for removal of tetracycline (TC) and ciprofloxacin (CIP) with excellent cyclic stability, owing to its large specific surface area as well as enhanced charge separation and visible light utilization. Our characterization revealed that h+ and ·OH are responsible for the photocatalytic degradation of TC and CIP. This work provides insights into the design of photocatalytic materials with synergy of adsorption and photocatalytic degradation, and offers a heterojunction construction strategy for addressing the increasingly severe environmental issues.

Anisotropic dispersion promoting and passivation protecting of CA@JNs@Zn2+ Janus nanosheets on epoxy anticorrosive coatings

Defects in the curing process of epoxy coatings tend to deteriorate the anticorrosion performance of the coatings. An important way to enhance the anticorrosion performance of epoxy coatings is to add flaky fillers. In this paper, anisotropic Janus nanosheets (JNs) were prepared and modified by cardanol (CA) and Zn2+. Then, the obtained CA@JNs@Zn2+ Janus composite nanosheets were introduced into epoxy coatings. When the content of CA@JNs@Zn2+ is 0.2 %, the mechanical properties and corrosion resistance of the coating were effectively improved. The tensile strength of 0.2 %-CA@JNs@Zn2+/EP coating is 79 % higher than that of pure epoxy coating. The EIS analysis showed that the low-frequency impedance of the coating remained as high as 16.45 Gohm·cm2 after 35 days of immersion, and remained above 10 Gohm·cm2 during the whole immersion period, which demonstrating the optimal corrosion resistance. This paper provides a theoretical basis for the preliminary application of Janus material in the field of anticorrosion, and the prepared composite coatings are expected to be used for anticorrosion in harsh environment.

Zero-valent Ni/NiO core-shell nanosheets supported on graphene for highly efficient dye adsorption: Isotherm, kinetic and thermodynamic study

In this study, a novel zero-valent nickel/nickel oxide@graphene nanosheets (ZVNi-NiO@Gr) composite was successfully fabricated by a single-step method and used as nanoadsorbents for the removal of crystal violet dye (CV) from its contaminated aqueous solution. Morphological characterization of nZVNi-NiO shows unique morphology with two-dimensional core-shell nanosheets supported on graphene layers. The one-step simultaneous preparation of nZNi-NiO nanosheets on the graphene notably limits the effect of nZNi-NiO agglomeration and enhanced the adsorption sites on the surface. The adsorption performance of ZVNi-NiO@Gr was investigated in terms of pH, temperature, initial concentration of CV dye, and contact period. The results showed that the maximum adsorption capacity climbed from 1028 to 1230 mg/g with increasing temperature from 30° to 45°C, and CV dye adsorption was preferable in alkaline media at pH 10. The isothermal and kinetic analysis showed that the nonlinear form of the Freundlich isotherm model and pseudo-second-order kinetic model is more fitting for adsorption data. The results of the thermodynamic study indicated that the adsorption of CV dye was spontaneous, endothermic and physical. The unique structure of ZVNi-NiO@Gr and the synergistic effect made it promising adsorbent for removing cationic dyes from aqueous media, and it can be used practically to treat wastewater of textile industries.