Defect-Driven MoS2 Nanosheets toward Enhanced Sensing Sensitivity.

In this study, S-deficient MoS2 was prepared using proton irradiation and then applied as sensing materials for the detection of NO2 gas. First, bulk MoS2 was treated by ultrasonics to produce 2D nanosheets of MoS2, which were subsequently bombarded by a flux of high-energy protons, resulting in the appearance of structural defects throughout MoS2. The proton fluxes were adjusted to different densities of 1 × 1011, 1 × 1012, 1 × 1013, and 1 × 1014 ions/cm2. The effects of proton irradiation on the defects, also referred to as atomic vacancies, were systematically investigated using Raman measurements to locate the E1 2g and A1g modes and X-ray photoelectron spectroscopy to determine the binding energy of Mo 3d and S 2p orbitals. It was revealed that the density of proton irradiation greatly affects the degree of S atom vacancies in irradiated MoS2, while also enhancing the n-type semiconducting behaviors of MoS2. The vacancy-rich MoS2 was then demonstrated to exhibit a higher response to NO2 gas compared to that of nonirradiated MoS2, showing a 4-fold increase in response within a concentration range from 1 to 20 ppm. These results could pave the way for new approaches to fabricating sensing materials.

Characterization and biological prospects of various calcined temperature-V2O5 nanoparticles synthesized by Citrus hystrix fruit extract.

In this study, a simple green synthesis of vanadium pentoxide nanoparticles (VNPs) was prepared by the extract of Kaffir lime fruit (Citrus hystrix) as a green reducing and stabilizing agent, along with the investigation of calcination temperature was carried out at 450 and 550 °C. It was affirmed that, at higher temperature (550 °C), the VNPs possessed a high degree crystalline following the construction of (001) lattice diffraction within an increase in crystalline size from 47.12 to 53.51 nm, although the band gap of the materials at 450 °C was lower than that of the VNPs-550 (2.53 versus 2.66 eV, respectively). Besides, the materials were assessed for the potential bioactivities toward antibacterial, antifungal, DNA cleavage, anti-inflammatory, and hemolytic performances. As a result, the antibacterial activity, with minimal inhalation concentration (MIC) < 6.25 µg/mL for both strains, and fungicidal one of the materials depicted the dose-dependent effects. Once, both VNPs exhibited the noticeable efficacy of the DNA microbial damage, meanwhile, the outstanding anti-inflammatory agent was involved with the IC50 of 123.636 and 227.706 µg/mL, accounting for VNPs-450 and VNPs-550, respectively. Furthermore, this study also demonstrated the hemolytic potential of the VNPs materials. These consequences declare the prospects of the VNPs as the smart and alternative material from the green procedure in biomedicine.

Premise setting for sustainable developing adsorption in environmental remediation using graphitic carbon nitride@agar-derived porous carbon composite.

In the adsorption process for wastewater treatment, the adsorbent plays an important role. A composite adsorptive material composed of graphitic carbon nitride and agar-derived porous carbon (CNPC) was fabricated from simple precursors (melamine, thiourea, and agar) and through a facile procedure with different melamine and thiourea ratios. Characterization of CNPC proved a successful formation of a porous structure consisting of mesopores and macropores, wherein CNPC holds distinctive electrochemical (lowered resistance and higher specific capacity) and photochemical properties (lowered bandgap to 2.33 eV) thanks to the combination of graphitic carbon nitride (CN) and agar-derived porous carbon (PC). Inheriting the immanent nature, CNPC was subjected to the adsorption of methylene blue (MB) dye in an aqueous solution. The highest adsorption capacity was 133 mg/g for CNPC-4 which was prepared using a melamine to thiourea ratio of 4:4 - equivalent to the removal rate of 53.2 % and following the pseudo-I-order reaction rate. The effect of pH points out that pH 7 and 9 were susceptible to maximum removal and pretreatment is not required while the optimal ratio of 7.5 mg of MB and 30 mg of material was also determined to yield the highest performance. Furthermore, the reusability of the material for three consecutive cycles was evaluated based on two methods pyrolysis at 200 °C and photocatalytic degradation by irradiation under visible light. In general, the photocatalytic regeneration pathway is more ample and efficient than pyrolysis in terms of energy efficiency (saving energy over 10 times) and adsorption capacity stability. As a whole, the construction of accessible regenerative and stable adsorbent could be a venturing step into the sustainable development spearhead for industries.

The removal enhancement of organic contaminations and optimization of the photocatalytic efficiency by Box-Behnken design using ZnO-TiO2/porous graphene aerogel.

In this study, zinc oxide-titanium dioxide/graphene aerogel (ZnO-TiO2/GA) was successfully synthesized through a simple and cost-effective hydrothermal self-assembly process. Besides, the surface response model and the experimental design according to the Box-Behnken model were selected to determine the optimal removal efficiency for crystal violet (CV) dye and para-nitrophenol (p-NP) phenolic compound. According to the obtained results, the highest degradation efficiency for CV dye of 99.6% was obtained under the following conditions: pH 6.7, CV concentration of 23.0 mg/L, and catalyst dose of 0.30 g/L. For p-NP, the degradation efficiency reached 99.1% under the following conditions: H2O2 volume of 1.25 mL, pH 6.8, and catalyst dose of 0.35 g/L. Therewithal, kinetic models of adsorption-photodegradation, thermodynamic adsorption, and free radical scavenging experiments were also investigated to propose the specific mechanisms involving the removal of CV dye and p-NP. According to the aforementioned results, the study provided a resulting ternary nanocomposite with great removal performance for water pollutants via the synergetic effects of adsorption and photodegradation processes.

Chitosan membrane drafting silver-immobilized graphene oxide nanocomposite for banana preservation: Fabrication, physicochemical properties, bioactivities, and application.

In this study, silver-immobilized graphene oxide/chitosan (AGC/CTS) membranes were assembled by the solvent evaporation method, wherein Curcuma longa extract was used to synthesize silver-immobilized graphene oxide (AGC) nanocomposite. The characterization results showed that the AGC was successfully synthesized with AgNPs distributed quite evenly on GO sheets. The as-prepared AGC also exhibited high antibacterial activity and low cytotoxicity towards normal cell lines compared to human epithelial carcinoma cell lines. Besides, the fabrication of AGC/CTS membranes was additionally assessed with different AGC ratios and thicknesses. The results revealed the membrane containing 3 wt% of AGC with great hygroscopicity and elastic modulus of 27.03 ± 3.07 MPa. The samples also performed excellent bactericidal capability, along with good mechanical properties for banana preservation. Therewithal, the membrane-coated bananas were also elucidated to ripen at slower paces and less damage, with no appearance of patches of mold on the banana peel surface, eventually prolonging the shelf life of bananas up to 10 days as compared to the non-coated ones. The aforesaid results confirm the potential application of the AGC/CTS membrane as a safe and alternative fruit preservation agent in the food industry.

Revisiting the roles of dopants in g-C3N4 nanostructures for piezo-photocatalytic production of H2O2: a case study of selenium and sulfur.

The sustainable production of hydrogen peroxide (H2O2) from oxygen and water has become an exciting research hotspot in the scientific community due to the importance of this fine chemical in various fields. Besides, piezo-photocatalysis is an emerging star for generating H2O2 from these green reagents. For developing catalysts for this specific application, doping heteroatoms into carbon-based materials such as graphitic carbon nitrides (g-C3N4) is a growing fascination among worldwide scientists. However, systematic study on the effects of doping precursors on the catalytic results is still rare. Herein, we fabricated sulfur (S) and selenium (Se) doped g-C3N4 with various doping precursors to evaluate the effects of these agents on the production of H2O2 under light and ultrasound irradiation. Based on the results, Se-doped g-C3N4 gave an outstanding catalytic performance compared to S-doped g-C3N4, even in a significantly low quantity of Se. In order to fully understand the chemical, physical, optical, and electronic properties of pristine g-C3N4 and its derivatives, the as-prepared materials were thoroughly analyzed with various tools. Thus, this study would give more profound insights into doping techniques for carbon-based materials and encourage further research on the design and development of piezo-photocatalysts for practical applications.

Green synthesis of chitosan-based membrane modified with uniformly micro-sizing selenium particles decorated graphene oxide for antibacterial application.

In this study, selenium microparticles (SeMPs) were green-synthesized by utilizing the Terminalia catappa leaves extract as an effective reducing agent. SeMPs were then decorated onto graphene oxide (GO) with the assistance of ultrasound using the ex-situ technique to obtain the SeMPs-GO composite. SeMPs and SeMPs-GO were thoroughly characterized with modern analytical methods, whereas the antibacterial performance of the composites was evaluated via the optical density method. Particularly, SeMPs-GO held up an inhibition of 99 % against both Gram-positive and Gram-negative bacteria strains as well as restrained 50 % of fungal activity. SeMPs-GO was additionally incorporated onto chitosan (CTS) to collect the SeMPs-GO/CTS membrane which was characterized by similar advanced analysis methods. The antibacterial property of the membrane was determined by the inhibition zone diameter. Furthermore, the membrane exhibited good thermal and mechanical characteristics, showing no sign of degradation at a temperature below 260 °C, and a tensile strength of 38 N/mm2. The swelling degree reached 148 % after 6 h of immersion in water, which was stable after 72 h (153 %). The obtained membrane can potentially be utilized for medical and food applications.

Fabrication of RHA-silica/graphene oxide nanocomposites for removal of lead ions from water.

In this study, rice husk ash-silica/graphene oxide (RHA-SiO2/GO) nanocomposites were synthesized by the in situ method using (3-aminopropyl) triethoxysilane as a coupling agent. The obtained products were used to remove lead ions (Pb2+) from aqueous solution. Effects of SiO2:GO mass ratio, contact time, pH and initial Pb2+ concentration on the adsorption capacity were studied. It was found that the suitable ratio of SiO2:GO for Pb2+ adsorption is 100:2. The suitable RHA-SiO2/GO was characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, Brunauer-Emmett-Teller specific surface area and thermal gravimetric analysis. Accordingly, RHA-SiO2/GO nanocomposite could be used as promising adsorbent for the removal of Pb2+ from water.