Hydrothermally prepared vertical multilayer WS2 nanosheets on the surface of few-layer MoS2 for the ultra-sensitive NO2 detection at room temperature.

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Scaffold-based tissue engineering approaches have been commonly used for skin regeneration or wound healings caused by diseases or trauma. For an ideal complete healing process, scaffold structures need to meet the criteria of biocompatibility, biodegradability, and antimicrobial properties, as well as to provide geometrical necessities for the regeneration of damaged tissue. In this study, design, synthesis and characterization of a three dimensional (3D) printable copolymer based on polycaprolactone-block-poly(1,3-propylene succinate) (PCL-PPSu) including anti-microbial silver particles is presented. 3D printing of PCL-PPSu copolymers provided a lower processing temperature compared to neat PCL, hence, inclusion of temperature-sensitive bioactive reagents into the developed copolymer could be realized. In addition, 3D printed block copolymer showed an enhanced hydrolytic and enzymatic degradation behavior. Cell viability and cytotoxicity of the developed copolymer were evaluated by using human dermal fibroblast (HDF) cells. The addition of silver nitrate within the polymer matrix resulted in a significant decrease in the adhesion of different types of microorganisms on the scaffold without inducing any cytotoxicity on HDF cells in vitro. The results suggested that 3D printed PCL-PPSu scaffolds containing anti-microbial silver particles could be considered as a promising biomaterial for emerging skin regenerative therapies, in the light of its adaptability to 3D printing technology, low-processing temperature, enhanced degradation behavior and antimicrobial properties.

The removal of toxic metals like lead (Pb) and cadmium (Cd) is very urgent keeping their hazardous effects in view. In this work, seeds of Albizia lebbeck and Melia azedarach trees were converted into activated carbon adsorbents and applied for the adsorptive removal of Pb and Cd metals from an aqueous solution. The as prepared adsorbents were characterised by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The removal efficiencies of both metals were strongly dependent on their initial concentration, contact time, pH, temperature and the quantity of adsorbents. 0.2 g of both adsorbents removed respectively 75 and 62% Pb and 77 and 66% Cd from from 100 ml of a 40 mg/l concentrated solution in 120 min at pH 5 and a temperature of 20°C. Both the Freundlich and Langmuir isotherms were well fitted to the experimental data. We believe that this work will provide a convenient way to synthesise low cost activated carbon adsorbents for the remediation of highly toxic metals from wastewater to safeguard our environment for future generations.

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The quest for advanced gas sensing materials to detect toxic gases at low temperatures has recently received much attention to ensure indoor and outdoor air quality. For this purpose, two-dimensional transition-metal dichalcogenides (TMDs) have received widespread interest due to their highly active sites for the adsorption of gas molecules and outstanding electrical, chemical, and optical properties, which enable the materials to be used as supercapacitors, electrocatalysts, photocatalysts, battery materials, and sensors. In the present work, MoS2 was vertically grown on the surface of porous C3N4 nanosheets (NSs) to form MoS2/C3N4 hybrid aerogels via freeze drying. The gas sensing performance of the composites was investigated toward NO2 gas at room temperature (RT). The as-prepared hybrid aerogel nanocomposite (MSN-2) showed abundant exposed active sites, a large number of pores, and high electronic density on the surface, thus exhibiting a 58-fold higher response than pristine MoS2 and C3N4 NSs. Furthermore, it showed short response/recovery time, commendable stability, and excellent selectivity toward NO2 gas. This work opens up an efficient way for the facile synthesis of edge-exposed MoS2 combined with highly porous C3N4 NSs for excellent NO2 gas sensing.

The 3D flower-like CoAl-layered double hydroxide (CoAl-LDH) was successfully prepared using the functional template agent of fluoride ions via a facile one-step hydrothermal route. Various techniques proved that all the samples presented 3D flower-like microstructural morphology. Representatively, the CA-2 sample, which was synthesized with the molar ratio of Co : Al of 3.65 : 1, had considerably abundant pores in its thin nanosheets. The average pore size was 2-4 nm, the specific surface area was equal to 49.45 m 2 g À1 , and the thickness of nanosheets was approximately 3.068 nm. The CA-2 sample showed an excellent response to 0.01-100 ppm NO 2 with ultrafast response/recovery time at room temperature (RT). The detection limit of the sensor even reached 10 ppb. The superior gas sensing performance could be attributed to the synergistic effects of the functional template agent of fluoride ions and specific porous 3D flower-like nanostructure. The current study showed that the 3D flower-like CoAl-LDHs might a promising material in practical detection of NO 2 at RT. Scheme 2 Schematic for the mechanism of NO 2 sensing for CoAl-LDHs. (a) SEM image of 3D flower-like CA-2 on Au electrode; (b and c) the model with response procedure of gas sensing; (d) I-V curve measured for CA-2 sensor in air and 50 ppm NO 2 exposure at RT; (e) IR spectra of CA-2 before and after NO 2 gas detection (CA-2 test NO 2 gas sensing for 2 h).21918 | RSC Adv., 2019,9,[21911][21912][21913][21914][21915][21916][21917][21918][21919][21920][21921] This journal is