•NVP exfoliated MoS2 nanosheets were successfully prepared with a recyclable method.•MoS2/Bi2Se3 (MB) hybrids were synthesized by a facile wet chemical method.•MB hybrids enhanced smoke suppression ...and flame retardancy of epoxy resin (EP).•MB hybrids also enhanced stretch resistance and anti-wear properties of EP matrix.
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Bimetallic compounds have been proved superior suppression effect on smoke emission during combustion of polymers. In this work, MoS2/Bi2Se3 (MB) hybrids were prepared by a facile wet chemical method and showed superior performance on smoke suppression of EP matrix during combustion. N-vinyl pyrrolidone (NVP) was employed to exfoliate molybdenum disulfide (MoS2) nanosheets in a recyclable method, which showed high efficiency and was recyclable. Exfoliated MoS2 exhibited large surface area and used as carriers to synthesize MB hybrids. Considering the catalytic effect of bismuth and molybdenum, the hybrids had a great influence on the smoke emission behaviors of EP composites. The smoke production was obviously suppressed during the flaming combustion (more than 22% and 23% decrease obtained from cone calorimeter and steady state tube furnace, respectively) or smolder processes (more than 23% decrease obtained from smoke chamber) at only 1 wt% content of MB hybrids. What's more, due to superior dispersion state, the addition of MB hybrids also enhanced the mechanical properties of EP matrix, including wear resistance and tensile property. This work provided a safe and green exfoliation method of MoS2 to prepare polymers/MoS2 composites and also constructed a novel binary hybrids for enhancing combination performances of polymers.
To integrate real-time monitoring and therapeutic functions into a single nanoagent, we have designed and synthesized a drug-delivery platform based on a polydopamine(PDA)/human serum albumin ...(HSA)/doxorubicin (DOX) coated bismuth selenide (Bi2Se3) nanoparticle (NP). The resultant product exhibits high stability and biocompatibility both in vitro and in vivo. In addition to the excellent capability for both X-ray computed tomography (CT) and infrared thermal imaging, the NPs possess strong near-infrared (NIR) absorbance, and high capability and stability of photothermal conversion for efficient photothermal therapy (PTT) applications. Furthermore, a bimodal on-demand pH/photothermal-sensitive drug release has been achieved, resulting in a significant chemotherapeutic effect. Most importantly, the tumor-growth inhibition ratio achieved from thermo-chemotherapy of the Bi2Se3@PDA/DOX/HSA NPs was 92.6%, in comparison to the chemotherapy (27.8%) or PTT (73.6%) alone, showing a superior synergistic therapeutic effect. In addition, there is no noticeable toxicity induced by the NPs in vivo. This multifunctional platform is, therefore, promising for effective, safe and precise antitumor treatment and may stimulate interest in further exploration of drug loading on Bi2Se3 and other competent PTT agents combined with in situ imaging for biomedical applications.
Theranostic nanoparticles which incorporate therapeutic and diagnostic properties in a single dose have the potential to advance personalized therapy in biomedical area. In this research work, a ...nanotheranostic agent i.e., nanocomposites of Bismuth Selenide (Bi2Se3) and Graphene Oxide (GO) in the presence of poly (vinyl) alcohol (PVA) has been fabricated via hydrothermal route. The XRD pattern confirmed the formation of Bi2Se3/GO/PVA nanocomposites showing rhombohedral structure. The crystallite size and lattice strain were calculated by Scherrer formula, Williamson-Hall and Scherrer plot methods. Average crystallite size measured by these methods was 13.06 nm, 12.6 nm and 12.76 nm. UV–Vis spectroscopy was used to study the optical properties such as absorption regions and band gap of the prepared nanocomposites. FTIR and EDAX analysis also confirmed the successful fabrication of Bi2Se3/GO/PVA nanocomposites. SEM revealed sheet-like morphology of prepared nanocomposites. The antibacterial activity of the nanocomposites was studied against two gram-negative bacteria ‘Escherichia coli’ and ‘Pseudomonas’ at 15 μg/ml and 25 μg/ml concentrations by disk diffusion technique. The zone of inhibitions against E. coli at 15 μg/ml and 25 μg/ml were 13 mm and 17 mm while against Pseudomonas were 15 mm and 18 mm. Also, the in vivo toxicity of the prepared Bi2Se3/GO/PVA nanocomposites was investigated on Swiss Albino mice with a high dose of 20 mg/kg at a time period of 2, 7, 14 and 30 days by analyzing hematological, biochemistry and pathological tests. No severe damage was observed in mice during whole treatment time which ensures that the synthesized nanocomposites were non-toxic. Moreover, p-value was calculated which shows that our nanoparticles are safe and that the manufactured nanoparticles have no significant effect on mice. This research work shows that Bi2Se3/GO/PVA nanocomposites are biocompatible and can be further studied for different biomedical applications like CT imaging, Photoacoustic imaging as well as Photothermal therapy.
•Synthesis and biomedical applications of Bi2Se3/GO/PVA nanocomposite are summarized.•Bi2Se3/GO/PVA nanocomposite behaves as amazing antibacterial agent.•The in vivo toxicity of the nanocomposites is tested for the first time.•Further exploration of Bi2Se3/GO/PVA nanocomposite in biomedical field is current need.
Topological Insulators are new classes of materials with insulating bulk but having gapless surface states. Integer Quantum Hall Effect, discovered in 1980 was the first property with topological ...association in topological insulators. For the last couple of decades different types of these exotic materials were foreseen, then revealed and fascinated the scientists due to their plethora of applications. Bi2Se3 is one of them with a single Dirac cone on its surface states and having the highest bulk band gap of 0.3 eV among all other topological insulator materials. While the transport properties of its single crystals are renowned, thin films are also causing equally sensational detections and very recently nanoparticles are also being used in some excellent innovations. In this manuscript, a review on the meticulous studies of Bi2Se3 is presented where different synthesis techniques; crystal structures; various physical properties and modern day applications were taken into concern.
The chemical reaction of gas adsorption/desorption is strongly correlated with the surface state of sensitive films. Thus, understanding the surface state and kinetic process of gas-sensing reactions ...is crucial to design highly active sensing films. In this study, bismuth selenide (Bi2Se3) was selected as the platform to clarify those matters. The noble metal nanocrystals (Au, Ag and Pt) were decorated on the (001) surface of layered Bi2Se3 to tune the surface state and improve the dynamical gas sensing parameter. The response and response rate toward 10 ppm of NO2 were respectively improved by 2.5 and 3.8 times by the Au decoration, and 2.3 and 3.2 times by the Ag decoration, and 1.3 and 2.7 times by the Pt decoration. The gas adsorption/desorption isotherm was established to analyze the reaction kinetic parameters of the response (S), kinetic reaction rate (kr and k-r) and beta value (β). These results demonstrate that noble metals can greatly promote the reaction kinetic parameters by modulation the surface state. Especially, the Au10 sample acquired maximum kr values of 633.963, which is 9.3 times higher than pure Bi2Se3. This work provides an important strategy for designing gas sensing performance between topological insulators and noble metal particles.
•The topological insulator was served as a platform for novel surface chemistry and catalysis.•Au, Ag and Pt were decorated to design high gas sensing performance by tuning the surface states.•The adsorption/desorption isotherm were established to clarify the mechanism.•This work paves a way to design high activity gas sensor
Topological insulators are very interesting from a fundamental point of view, and their unique properties may be useful for electronic and spintronic device applications. From the point of view of ...applications it is important to understand the decay behavior of carriers injected in the band gap of the topological insulator, which is determined by its complex band structure (CBS). Using first-principles calculations, we investigate the dispersion and symmetry of the complex bands of Bi2Se3 family of three-dimensional topological insulators. We compare the CBS of a band insulator and a topological insulator and follow the CBS evolution in both when the spin-orbit interaction is turned on. We find significant differences in the CBS linked to the topological band structure. In particular, our results demonstrate that the evanescent states in Bi2Se3 are non-trivially complex, i.e. contain both the real and imaginary contributions. This explains quantitatively the oscillatory behavior of the band gap obtained from Bi2Se3 (0 0 0 1) slab calculations.
Bismuth selenide (Bi2Se3) is an attractive visible-light-responsive semiconductor that can absorb a full range of visible and near-infrared light. However, its poor redox capacity and rapid carrier ...recombination limit its application in photocatalytic oxidation. In this study, we adopted Bi2Se3 as the couple part of graphitic carbon nitride (g-C3N4) to construct a Bi2Se3/g-C3N4 composite photocatalyst. Through in situ fabrication, the self-developed Bi2O3/g-C3N4 precursor was transformed into a Bi2Se3/g-C3N4 heterojunction. The as-prepared Bi2Se3/g-C3N4 composite exhibited much higher visible-light-driven photocatalytic activity than pristine Bi2Se3 and g-C3N4 in the removal of phenol. The enhanced photocatalytic activity was ascribed to the S-scheme configuration of Bi2Se3/g-C3N4; this was confirmed by the energy-level shift, photoluminescence analysis, computational structure study, and reactive-radical testing. In the S-scheme heterojunction, photo-excited electrons in the conduction band of g-C3N4 migrate to the valence band of Bi2Se3 and combine with the excited holes therein. By consuming less reactive carriers, the S-scheme heterojunction can not only effectively promote charge separation, but also preserve more reactive photo-generated carriers. This property enhances the photocatalytic activity.
Under visible light irradiation, the Bi2Se3/g-C3N4 composite exhibited superior photocatalytic activity for the degradation of phenol through an S-scheme mechanism.
Bismuth selenide (Bi2Se3) is a topological insulator with metallic surface states (SS) residing in a large bulk bandgap. In experiments, synthesized Bi2Se3 is often heavily n-type doped due to ...selenium vacancies. Furthermore, it is discovered from experiments on bulk single crystals that Bi2Se3 gets additional n-type doping after exposure to the atmosphere, thereby reducing the relative contribution of SS in total conductivity. In this article, transport measurements on Bi2Se3 nanoribbons provide additional evidence of such environmental doping process. Systematic surface composition analyses by X-ray photoelectron spectroscopy reveal fast formation and continuous growth of native oxide on Bi2Se3 under ambient conditions. In addition to n-type doping at the surface, such surface oxidation is likely the material origin of the degradation of topological SS. Appropriate surface passivation or encapsulation may be required to probe topological SS of Bi2Se3 by transport measurements.
We report the discovery of a temperature-induced phase transition between the α and β structures of antimonene. When antimony is deposited at room temperature on bismuth selenide, it forms domains of ...α-antimonene having different orientations with respect to the substrate. During a mild annealing, the β phase grows and prevails over the α phase, eventually forming a single domain that perfectly matches the surface lattice structure of bismuth selenide. First-principles thermodynamics calculations of this van der Waals heterostructure explain the different temperature-dependent stability of the two phases and reveal a minimum energy transition path. Although the formation energies of freestanding α- and β-antimonene only slightly differ, the β phase is ultimately favored in the annealed heterostructure due to an increased interaction with the substrate mediated by the perfect lattice match.
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