FlatChem最新文献

Liquid suspensions of phosphorene nanolayers (2D-bP) obtained through liquid phase exfoliation (LPE) of elemental black phosphorus (bP) have been prepared and extensively characterized. The exfoliating ability of deionized water (DI water), dihydrolevoglucosenone, (Cyrene), and N-methyl-2-pyrrolidone (NMP) has been investigated and compared along with the differences in the structure, concentration, and stability of the collected nanoflakes. Water was chosen as an exfoliating medium due to its harmlessness and cost-effectiveness and because it is the safest solvent for further potential biomedical applications. Cyrene is a new bio-based solvent still under study. NMP, which is among the most widely used solvents for the exfoliation of 2D systems including bP, has been employed for comparison. The obtained suspensions have been characterized by Dynamic Light Scattering (DLS), Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), Phosphorus ³¹ Nuclear Magnetic Resonance (³¹P NMR), Transmission Electron Microscopy (TEM), Ultraviolet -Visible (UV–Vis), and Raman spectroscopies. The stability of 2D-bP suspensions over time and their photoactivity, i.e., their ability to generate singlet oxygen species as a photosensitizer, have been investigated. The collected results evidenced that the exfoliation of bP in different solvents, including DI water, resulted in satisfactory and comparable nanoflake structures and features. The singlet oxygen generation through irradiation of 2D-bP in DI water suspensions, advantageously obtained directly from LPE, showed promising potential for use in photodynamic therapy (PDT). Preliminary data on the potential biomedical application of 2D-bP to inhibit the insulin self-assembly into amyloid aggregates as well as to cause fibrils disassembling through simple incubation or photoactivity, are also discussed.

Locating and recovering the victims as a result of disaster events is extremely challenging due to vast search areas, hazardous nature of destroyed infrastructure, and large number of potential victims. An effective avenue for the victim’s detection is through the sensing of human-specific volatile organic compounds (VOCs) emitted both in life and in death. Motivated by this, we employed first principles density functional theory (DFT) calculations to study the sensing properties of pristine, vacancy-induced and single atom dispersed tungsten disulfide (WS₂) monolayers towards 11 specific VOCs associated with decomposing humans. We found that pristine, and vacancy-induced WS₂ weakly adsorbed the selected VOCs with adsorption energies (E_ads) between −0.26 to −0.76 eV. However, the incorporation of selected single atoms of Co, Fe, Nb, and Ni in WS₂ improved the sensing properties tremendously. In particular, Nb-WS₂ adsorbed the incident VOCs with E_ads values of −1.89, −209, −1.43, −0.94, −2.08, −1.57, −1.44, −1.47, −1.70, −1.03, and −2.14 eV for 2-Butanone, benzaldehyde, butanol, heptane, hexanal, methylamine, dimethyl disulfide, dimethyl trisulfide, pyridine, octane, and toluene, respectively, which are ideal for efficient sensing mechanism. Appropriate adsorptions were coupled with the measurable changes in the electronic properties (band gaps) of Nb-WS₂, which is essential for proficient sensing. Charge transfer analysis, electro localization functions, electrostatic potentials, and work function calculations further authenticated the sensing propensities of single atom dispersed WS₂. Finally, Langmuir adsorption model was employed to explore the sensing at diverse pressure and temperature settings. We believe that these results will help for the development of highly efficient nanosensors for the detection of VOCs related to decomposed humans in mass disaster events. This will increase the detection ability and the chance of locating these victims.

Dive into the captivating world of Transition Metal Dichalcogenides (TMDCs), classic compounds with the formula TMX₂, promising potent photocatalytic prowess in degrading emerging pollutants, notably antibiotics. The hybridized form of TMDCs steals the spotlight, showcasing an enhanced ability for antibiotics degradation due to corresponding synergetic effect, as observed from the literature. The narrative explores key factors influencing antibiotics degradation, encompassing a wide array of photocatalytic synthesis approaches and strategies for boosting its performance. Detailed studies on antibiotics degradation using hybrid TMDCs vividly illustrate the growing foothold of research in this direction. Through addressing the challenges faced by TMDC hybrid photocatalysts in antibiotic degradation, the present review not only unveils obstacles but also suggests prospective solutions for the future. This concise yet comprehensive review serves as a global compass, inviting researchers worldwide to delve into the realm of hybrid TMDC photocatalysts and contribute to our collective understanding. In the face of environmental challenges, this review offers valuable insights, pointing the way toward a cleaner and sustainable future.

Magnesium and its alloys possess low density and superior specific strength making it a potential structural metal to be used in different engineering fields. However, its proneness to corrosion limits its applications. In this novel study, an eco-friendly graphene-oxide coating was prepared on AZ31 magnesium alloy via electrophoretic deposition to enhance its anti-corrosion properties. Scanning electron microscopy coupled with energy dispersive spectroscopy, atomic force microscopy, and scratch test were adopted to investigate surface morphology, roughness, chemical composition, and adherence of the coating. The corrosion behaviour of graphene-oxide coated alloy was studied using potentio-dynamic polarization and electrochemical impedance spectroscopy tests in 3.5 wt% NaCl and Borate Buffer solutions. The obtained results demonstrate that the coating developed on AZ31 alloy is smooth and adherent with the hardness of the as-deposited coating measuring as high as 6.0 GPa. In addition, the electrochemical corrosion behaviour studies revealed that the coating significantly increased the corrosion potential (E_corr) of the alloy towards more noble values (−0.65 V < E_corr < −0.35 V), with the coated alloys possessing a charge transfer resistance nearly two orders of magnitude greater than their non-coated counterparts. Consequently, the corrosion rate of the coated alloy decreased substantially, indicating that the coating exhibits exceptional corrosion resistance (0.045–0.09 mm/a in 3.5 wt% NaCl and 0.002–0.006 mm/a in Borate Buffer). These findings challenge the conventional beliefs that graphene exhibits strong cathodic behaviour towards anodic materials such as AZ31 alloy. Thus, the outcomes not only have the potential to revolutionize the advancement of graphene-oxide coatings for corrosion resistance but could also possibly expand AZ31 alloy’s applications in the aerospace and automotive sectors.

Layered double hydroxides (LDHs) are attractive bidimensional materials for electrochemical applications because of their high activity in the oxygen evolution reaction (OER). However, their limited bifunctionality due to the slow kinetics of the oxygen reduction reaction (ORR) is a bottleneck for their use in secondary Zn-air batteries (ZABs). In this work, cobalt-free NiMn LDHs were rationally designed by optimizing the Ni composition and incorporating surface defects onto the LDH (oxygen vacancies, Ov) while performing interface engineering using a carbonaceous support enriched with nitrogen heteroatoms. The LDHs without induced defects presented the optimal activity for the OER at a 3:1 Ni/Mn atomic ratio (onset potential 1.47 V vs. 1.45 V for IrO₂/C), while the ORR was unfavorable. However, the further optimization by introducing Ov and N–heteroatoms (labeled as Ov-NiMn LDH/NCNTG) allowed bifunctionality by improving the onset potential to 0.90 V while decreasing the half-wave potential difference from 180 mV for the material without induced defects to 100 mV, and by improving the limiting current density by a factor of two. In this regard, density of states (DOS) calculations suggested that surface defects improved the electronic transfer while decreasing the oxygen adsorption energy. ZAB tests indicated that the interface-engineered material allowed a battery voltage of 1.47 V, and a power density of 64 mW cm⁻². The battery also maintained stability over 180 charge/discharge cycles at 10 mA cm⁻² (50 h), with ΔV below 150 mV between the initial and final cycles.

Graphene-based nanomaterials (GBNMs) are versatile due to their large surface area, great mechanical, chemical strength, and excellent electrical properties. The versatility of graphene has increased its applicability therefore several synthesis methods to produce high quality graphene simpler, faster, and cost-effectively are actively explored. The conventional synthesis methods however employ toxic chemicals, high temperatures, and lengthy synthesis times. On the other hand, the gamma (γ) irradiation approach is facile, occurs under ambient conditions and produces graphene composites of high purity. Noteworthy, this technique enables the user to control the synthesis time and total dose, hence minimising the aggregation of the nanomaterial, the main drawback hindering the commercial production of GBNMs. γ-radiolysis synthesized GBNMs exhibit superior optical and electrical properties and hence improved supercapacitance, catalytic, and sensing abilities. Although other reviews addressed the γ-ray synthesis of metallic nanomaterials, polymers, as well as usage of a variety of radiation techniques to fabricate graphene composites, this review focuses solely on the synthesis and modifications of GBNMs via the γ-synthesis technique. Properties of graphene and conventional methods used to reduce graphene oxide (GO) to graphene as well as their shortcomings are highlighted. This is followed by detailing the γ-radiation synthesis technique, its advantages over the conventional methods and the principles thereof. Effects of γ-irradiation and the conditions required for the structural modification of graphene to obtain different graphene composites are detailed. The influence of operational parameters on the fabricated graphene-based composites are discussed followed by summaries of recent developments in the applicability of γ-irradiated GBNMs in catalysis, energy, sensing, and biomedical fields. In addition, this paper presents insights into the challenges posed and provides future research directions and prospects in the field of γ-irradiated GBNMs.

This research explores the efficacy of photodynamic therapy (PDT) and photothermal therapy (PTT) in combating chemotherapy-resistant diseases. This study focuses on enhancing tumor treatment effectiveness by leveraging the synergetic effects of combining PDT and PTT through the development of Fe-nitrogen-carbon (FeNC) nanoparticles with superior photostability. These nanoparticles, functioning as photosensitizers for the combined PDT/PTT treatment, can generate both type I and type II ROS and heat upon 808 nm irradiation. Notably, the FeNC nanoparticles demonstrate an exceptional photothermal conversion efficiency (34 %), surpassing commonly used PTT photosensitizers. In vitro and in vivo experiments corroborate the efficiency of FeNC as a photosensitizer in achieving significant tumor inhibition. In conclusion, the FeNC nanoparticles present promising applicability in the synergistic PTT/PDT treatment of tumors.

Pt-functionalized graphene shows promise for near-ambient hydrogen storage due to graphene’s potential as a hydrogen host and platinum’s role as a catalyst for the hydrogen evolution reaction and spillover effect. This study explores Pt cluster formation on epitaxial graphene and its suitability for hydrogen storage. Scanning Tunneling Microscopy reveals two growth pathways. Initially, up to $\sim$1 monolayer of Pt coverage, Pt tends to randomly disperse and cover the graphene surface, whereas the cluster height remains unchanged. Beyond a coverage of 3 monolayer, the nucleation of new layers on existing clusters becomes predominant, and the clusters mainly grow in height. Thermal Desorption Spectroscopy on hydrogenated Pt-decorated graphene reveals the presence of multiple hydrogen adsorption mechanisms. Two Gaussian peaks, which we attribute to hydrogen physisorbed (peak at 155°C) and chemisorbed (peak at 430°C) on the surface of Pt clusters are superimoposed on a linearly increasing background assigned to hydrogen bonded in the bulk of the Pt clusters. These measurements demonstrate the ability of Pt-functionalized graphene to store molecular hydrogen at temperatures that are high enough for stable hydrogen binding at room temperature.

Developing highly active, low-cost, and robust transition metal-based phosphide for alkaline overall water splitting is of utmost important to promote the practical application from fundamental. Herein, two-dimensional (2D) Mo-doped NiCoP nanoplates with novel amorphous/crystalline heterostructure (Mo(0.05)-NiCoP) in situ grown on three-dimensional nickel foam (NF) has been successfully constructed through hydrothermal reaction followed by the phosphorization treatment. Benefited from the synergy of amorphous/crystalline heterointerface, Mo doping, and unique 2D structure, the optimized Mo(0.05)-NiCoP exhibits outstanding electrocatalytic activity for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), achieving low overpotential of 67 mV at 10 mA cm⁻² for HER and 233 mV at 10 mA cm⁻² for OER. Meanwhile, there are only a cell voltage of 1.569 V was required to drive 10 mA cm⁻² when Mo(0.05)-NiCoP used as both anode and cathode for overall water splitting. Thus, this study provides a novel approach to construct efficient 2D bifunctional catalysts with amorphous/crystalline heterostructure and heterogeneous metal doping.

The hexagonal Boron Nitride (hBN) nanostructures with tuned physicochemical properties find huge applications in optoelectronic devices. Herein, we have synthesized nanocomposite of hBN with graphene oxide (GO) in various ratios to acquire composition-dependent variation in their structural, surface electronic, linear, and non-linear optical properties. The insertion of GO in hBN nanosheets has modified their strain landscape, the electronic charge transfers from GO to hBN, increased the working time of free charge carriers, and suppressed electron-hole recombination, thus modifying its work function (WF). GO-hBN nanocomposites observed to have reduced bandgap where creation of defect induced mid-gap states lead to enhancement in non-linear absorption of two photons. Herein, we have established a linear relationship between Urbach energy (E_u), a measure of disorders and non-linear absorption coefficient (α_NL). Additionally, we have observed that the tuned bandgap of the nanocomposites has significantly enhanced their performance as high-performance photocatalysts for the degradation of methyl orange, compared to bare hBN or GO. As a result, we discovered that E_u, α_NL, WF and photodegradation activity of GO-hBN nanocomposites exhibit analogous variations in response to changes in the content of GO. Thus, by strategically prioritizing the modification of a single parameter while considering the potential effects on other relevant properties for application purpose, GO-hBN can effectively harness large spectrum areas for catalytic and optoelectronic applications.