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AbstractBismuth selenide is a promising semiconductor for optoelectronics and energy conversion, including solar cells and aerospace applications. However, it degrades at high temperatures, affecting stability. According to the previous literature, we can solve this problem and easily tune under high pressure, but no reports are available for response against acoustic shock waves. To explore this, commercially available Bi2Se3 was purchased and tested under acoustic shock wave exposure. Bi2Se3 was subjected to 100, 200, 300, and 400 acoustic shock waves with 0.59 MPa transient pressure at 520 K temperature and 1.5 Mach number. Before and after shock-loaded Bi2Se3 samples were characterized using XRD, Raman, UV-DRS, PL, and FE- SEM and EDX. Under acoustic shock waves, Bi2Se3 exhibits increased crystallite size and reduced strain rate, promoting good thermal stability. It also shows a smaller bandgap and enhanced PL intensity, which ensures efficient solar cell operation. As a result, the material demonstrates improved thermal insulation and durability, which are crucial for stability and protection in extreme conditions for aerospace applications. These improvements make Bi2Se3 more suitable for solar cell and aerospace applications. [ABSTRACT FROM AUTHOR]

Metal selenides (MSes) have great potential as candidate anode materials in high‐specific‐energy sodium‐ion batteries (SIBs) but are plagued by rapid capacity degradation and slow kinetics. Here, it is reveal that the Bi2Se3 anode discharge process involves multiple‐types of sodium polyselenides (Na‐pSex) which suffer from terrible dissolution and shuttling properties. Based on these observations, a nanoflower‐like composite of dual carbon‐confined Bi2Se3−x crystallites is designed via facile defect chemistry. The robust dual N‐doped carbon layer suppresses the precipitation and aggregation of Bi2Se3, significantly alleviating the dissolution and shuttle effect of Na‐pSex. Theoretical calculations indicate that the pyridine/pyrrole nitrogen sites exhibit strong van der Waals resistance and chemisorption properties against Na2Se4 and Na2Se2. Furthermore, the abundant Se vacancies improve the inherent conductivity of Bi2Se3, reduce the diffusion barrier of Na+, and accelerate the reaction kinetics. Consequently, the resulting Bi2Se3−x@DNC electrode exhibits extraordinary durability (over 2000 cycles at 10.0 A g−1) and high‐rate capability (354.4 mAh g−1 at 75.0 A g−1), propelling the battery performance to new heights. Encouragingly, the assembled hybrid capacitor displays competitive rate performance and an ultra‐long lifespan exceeding 40 000 cycles, making the Bi2Se3−x@DNC electrode a promising candidate for SIBs. [ABSTRACT FROM AUTHOR]

A new type of bismuth selenide nanosheet layer material was synthesized by solvent thermal method, which is harmless to human body and can be used in combination with hydrogen peroxide solution as a new type of modern insecticide. The particle size of the bismuth selenide nanosheet material is about 80 nm, and it has good dispersion in water. In this experiment, the antibacterial ability of the material was investigated using Escherichia coli and Staphylococcus aureus as bacterial models and plant pathogens such as strawberry gray mold and tomato gray mold as fungal models. In addition, the in vivo bioassay indicated that Bi2Se3+H2O2 possessed effective control against Pepper Anthrax Disease. The biocompatibility of this material was also investigated using human umbilical vein endothelial cells (HUVEC) as a model, and the results showed that the bismuth selenide nanosheet material has good antibacterial ability and biocompatibility.

Aqueous potassium‐ion batteries with inherent safety, high abundance, and competitive hydrated ion‐radius point to future availability in energy storage. However, the extensively studied electrodes (metal‐oxides, Prussian‐blue‐analogues, etc.) typically suffer from undesirable capacities and sluggish kinetics owing to overwhelming ion diffusion barriers. Herein, for the first time, the metal chalcogenide bismuth selenide reinforced by iodine‐doping (I‐Bi2Se3) is implemented for high‐performance aqueous potassium‐ion storage. The co‐intercalation mechanism of potassium‐ion with proton in I‐Bi2Se3 is entirely revealed by operando synchrotron X‐ray diffraction and substantial ex‐situ analysis, and the excellent interlayer diffusion kinetics in the high‐conductive host are further enhanced by iodine‐doping, as proposed by theoretic calculations. Therefore, the resulting high diffusion coefficient and low interfacial transfer resistance endow I‐Bi2Se3 with superior rate performance (109.2 mAh g−1 at 10 A g−1) and cycling stability (91% capacity retention after 1200 cycles). Employing in hybrid‐ion batteries matching zinc metal, the highest reversible aqueous potassium‐ion storage to date of 316.8 mAh g−1 is demonstrated, permitting the establishment of reliable performance pouch cells. The promising aqueous potassium intercalation chemistry built in the improved metal chalcogenide is proven to be extendable to other hybrid‐ion devices, offering novel mechanistic insights and material practices for aqueous energy storage. [ABSTRACT FROM AUTHOR]

The physical parameters of solid-state produced tin and tellurium co-doped bismuth selenide polycrystalline crystals were described. Powder X-ray diffraction revealed the hexagonal structure in the samples' phase domination. A field emission scanning electron microscope was used to analyze the surface microstructure. Thermoelectric properties such as Seebeck coefficient, electrical resistivity, and thermal conductivity were analyzed in the temperature range 10–350 K. The electrical resistivity of (Bi0.96Sn0.04)2Se2.7Te0.3 was found to be four times lower than that of pure Bi2Se3. Due to donor-like effects and antisite defects, the Seebeck coefficient demonstrates a p- to n-type semiconducting transition. When compared to pure Bi2Se3, power factor and thermoelectric figure of merit of (Bi0.96Sn0.04)2Se2.7Te0.3 is found to increase by 15 and 9 times respectively. Tellurium excess boosts tin vacancies, promoting the p to n-type transition in (Bi0.96Sn0.04)2Se2.7Te0.3, making it a good option for low temperature thermoelectric and sensor applications. [ABSTRACT FROM AUTHOR]

The investigation of electrode materials for urea level determination (non-enzymatic) is advantageous to monitor patient's clinical health and prevention of milk adulteration. Chalcogenides have prospective applications in electrocatalysis because of their fast charge transfer and large specific surface area in terms of non-enzymatic sensing via redox reactions, which is of great significance. However, despite their tremendous relevance, they continue to present significant problems. To address this issue, a new parkerite-type compound, Ni3Bi2Se2, was synthesized using the capping agent sodium laurel sulfate through a hydrothermal process. The physical characterization of the ternary chalcogenide Ni3Bi2Se2 was done by X-ray photoelectron spectroscopy, scanning electron microscopy, powder X-ray diffraction, and photoluminescence. The analytical performances of the suggested sensor electrode, including sensitivity, the limit of detection (LOD), limit of quantification (LOQ), stability, and durability, were obtained by various electrochemical techniques. The lower limit of detection (LOD-6.05 µM), sensitivity (10.9 mA µM−1 cm−2) and lower limit of quantification (LOQ-18.35 µM) were derived using the calibration curve. Moreover, it provides accurate results when detecting urea in human urine samples. The prepared electrode shows outstanding sensitivity, selectivity, superior reproducibility, and long-term stability. [ABSTRACT FROM AUTHOR]

Topological insulators (TIs) exhibit unconventional quantum phases that can be tuned by external quantum confinements. The geometry of the surface of 3D TIs plays a crucial role. For example, the geometrical crossover from 2D surfaces to a 1D cylinder results in a novel state with a Spin‐Berry Phase (SBP). Surface‐Enhanced Raman Scattering (SERS) with a sub‐micron spatial resolution is utilized to study the quantum‐confinement effects of quasi‐relativistic electrons along the perimeter of the circular bismuth selenide (Bi2Se3) nanowires. The presence of diameter‐dependent SERS in nanowires can be attributed to the self‐interference effect of the electronic wave‐function along the circumferential direction of the TI nanowires. Nanoribbons with rectangular cross‐section do not show this effect. Further gold nanoparticles are applied as plasmonic SERS sensors attached to the distinct topological surface states to manipulate quasi‐relativistic surface states of nanoribbons and nanowires. This technique enables to discriminate between different geometries of TI surface states and also opens a novel pathway to probe the quantum properties of topological surface states. [ABSTRACT FROM AUTHOR]

Tick Hill gold deposit is a unique gold mineralisation style in the Mary Kathleen Fold Belt in the Mount Isa Inlier. The gold at Tick Hill is generally pure without silver and was formed during two discrete metamorphic-deformation events (D1 and D3). Early gold was observed as inclusions or coarse grains hosted within D1 peak-metamorphic diopside, scapolite and hornblende from the garnet–biotite–hornblende (tschemakite)–plagioclase (andesine)–quartz assemblage. Late gold is closely associated with bismuth selenide, chlorite, albite, sericite and K-feldspar, and formed during D3. The syn-D1 garnet–plagioclase–hornblende–quartz–biotite assemblage was used to constrain the pressure and temperature (P–T) conditions of metamorphism and mineralisation using the garnet–plagioclase–hornblende–quartz barometer and the hornblende–plagioclase, garnet–biotite and garnet–hornblende thermometers. The results show that peak metamorphism at Tick Hill reached P–T conditions of 6.0–7.6 kbar and 720–760 °C. These P–T conditions together with gneissic and migmatisation textures recorded in different rock types at the Tick Hill area indicate that the peak metamorphism preserved in the area occurred at the amphibolite–granulite facies, compared with the amphibolite facies at the southern Mary Kathleen and Eastern Fold Belt. The D3 chlorite, which formed during stage 2 to stage 4 mineralisation events, displays a wide range of compositions reflecting a gradual retrograde temperature change from ∼380 °C to ∼130 °C. The pressures during D3 could not be reliably determined, but the presence of various Bi-selenides suggests that towards the waning stages of D3, the rocks may have been exhumed to a pressure less than 1 kbar. The 1790–1770 Ma D1 peak metamorphism at Tick Hill reached 6–7.6 kbar and 720–760 °C. The 1525–1520 Ma D3 hydrothermal mineralisation at Tick Hill Deposit occurred at temperatures between ∼380 °C and ∼130 °C. The main D3 gold accumulation episodes at Tick Hill occurred at temperatures ranging from ∼380 to 160 °C. [ABSTRACT FROM AUTHOR]

In this paper, Bi2ZnxSe3-x with compositions x = 0 and x = 0.25 were synthesized using the melt technique at 850˚C. The crystal structures and surface morphologies of both the samples were investigated with X-ray diffraction (XRD), Raman spectroscopy and field emission scanning electron microscopy (FESEM), respectively. XRD spectra of both the bulk alloys of Bi2ZnxSe3-x (x = 0 and x = 0.25) revealed a polycrystalline nature with a hexagonal structure. UV-Vis absorbance spectra have shown that Zn doping increases the optical band gap while decreasing the absorbance edge. The activation energy (Ea) as calculated using Arrhenius plot revealed that Zn doping in place of Se results in a decrease in Ea. The variation in resistance with temperature highlights the prevalence of phonon-phonon and electron-phonon scattering as the dominant mechanisms. Topological insulators, due to their ability to suppress intrinsic electron backscattering, are viable recommendations for use as counter electrode materials in photovoltaic cells. This approach is poised to create a novel pathway for the future commercialization of flexible photovoltaic applications.

The acousto-optic modulation over a broad near-infrared (NIR) spectrum with high speed, excellent integrability, and relatively simple scheme is crucial for the application of next-generation opto-electronic and photonic devices. This study aims to experimentally demonstrate ultrafast acousto-optic phenomena in the broad NIR spectral range of 0.77–1.1 eV (1130–1610 nm). Hundreds of GHz of light modulation are revealed in an all-optical configuration by combining ultrafast optical spectroscopy and light–sound conversion in 10–20 nm-thick bismuth selenide (Bi2Se3) van der Waals thin films. The modified optical transition energy and the line shape in the NIR band indicate phonon–photon interactions, resulting in a modulation of optical characteristics by the photoexcited interlayer vibrations in Bi2Se3. This all-optical, ultrafast acousto-optic modulation approach may open avenues for next-generation nanophotonic applications, including optical communications and processing, due to the synergistic combination of large-area capability, high photo-responsivity, and frequency tunability in the NIR spectral range. [ABSTRACT FROM AUTHOR]

Background: Radiotherapy is one of the primary treatments for cancer, but it can cause damage to normal tissues and lead to side effects. The use of radiosensitizers can enhance the sensitivity of cancer cells to radiation, thereby reducing the amount of radiation required and minimizing damage to healthy tissues. Bismuth selenide nanoparticles (Bi2Se3 NPs) have been shown to have potential as radiosensitizers. Materials and methods: In this study, we investigated the potential of Bi2Se3 NPs as a radiosensitizer in colon cancer cells (HCT-116) in vitro. The cells were treated with various concentrations of Bi2Se3 NPs and then exposed to ionizing radiation. The viability of the cells was assessed using the MTT assay, and the survival rate was evaluated. Results: Our results showed that Bi2Se3 NPs significantly enhanced the sensitivity of colon cancer cells to ionizing radiation in a dose-dependent manner. The combination of Bi2Se3 NPs and radiation resulted in a significant decrease in cell viability and survival rate compared to radiation alone. Conclusion: Bi2Se3 NPs have the potential to be used as a radiosensitizer in the treatment of colon cancer. The findings of this study suggest that combining Bi2Se3 NPs with radiation may enhance the effectiveness of radiotherapy and reduce the mortality rate associated with colon cancer. Further studies are needed to investigate the safety and efficacy of this approach in vivo.

Absorption-dominant electromagnetic interference (EMI) shielding materials are promising in reducing electromagnetic radiation pollution, but their preparation processes are usually difficult and unsuitable for large-scale preparation. In this work, multiple folded Bi2Se3/PVDF nanocomposite films were fabricated by using a convenient tape-casting method and multiple folding, which can be easily extended in industrial applications. The EMI shielding effectiveness (SE) of the composite materials was investigated, which shows typical absorption-dominant behavior and can substantially reduce secondary reflections. Specifically, for the 35%(in volume) Bi2Se3/PVDF nanocomposite film, the SEA of single-layered film with a thickness of 60 μm reaches 20 dB while SER is lower than 5 dB. After folding the film into eight layers, the SEA increased to 50 dB while SER remains below 5 dB. This method provides an effective way to the fabrication of absorption-dominant electromagnetic absorption (EMA) and EMI shielding material.

Assessing the nature of topological quantum materials, and in particular probing the existence of topological surface states, is a very challenging task. Terahertz (THz) frequency scattering near‐field optical microscopy has emerged as an effective technique to investigate the presence of massless surface carriers by locally probing collective surface excitations, i.e., plasmon polaritons, whose dispersion critically depends on the density and nature of surface carriers. Here, thin (14–19 nm) films of Bi2Se3 are experimentally investigated through a combination of x‐ray diffraction, Hall‐bar magneto‐transport, and near‐field detectorless optical holography at THz frequencies, from 2 to 4.3 THz. The dispersion of surface plasmon polaritons are determined for different Bi2Se3 film thicknesses, proving the presence of massless surface carriers. The results open intriguing opportunities in THz nano‐plasmonics and topological nano‐photonics including the development of superlenses and metasurfaces, making use of plasmon polaritons. [ABSTRACT FROM AUTHOR]

Driven by the visible band gap, silver bismuth selenide (AgBiSe2) was loaded in PVDF/PEO blend to enhance the photodegradation of Maxilon blue dye. AgBiSe2 nanoparticles were successfully synthesized by facile solvothermal approach and then loaded to PVDF/PEO (80/20) by 10, 20, and 30 wt%, by evaporative casting method. The X‐ray results in tandem with the Fourier transform infrared (FTIR) established the successful fabrication of (PVDF/PEO)/x(AgBiSe2) polymer nanocomposites. The X‐ray analysis verified the formation of hexagonal AgBiSe2 of a crystallite size ranging from 14.3 to 23.24 nm. The FT‐IR results manifested an overlap between functional groups that corroborated the interaction between PVDF and PEO. Peaks of the AgSe, and SeO modes confirmed that the nanofiller and PVDF/PEO blend were successfully incorporated. The micrograph images by field emission scanning electron microscope (FESEM) unraveled the high tendency of AgBiSe2 to form a uniform cluster. The optical band gap was found to be a direct band gap of 2.86 eV for 30 wt% AgBiSe2 proving its validity as visible‐light‐driven photocatalysts. The removal percentages of the prepared membrane are 4.1, 59, 82, and 98 for 0, 10%, 20%, and 30% AgBiSe2 after 300 min of irradiation under simulated sunlight at pH 6. [ABSTRACT FROM AUTHOR]

Topological insulators are materials that in bulk mode have band gap such as an ordinary insulator but can protect the conduction mode at the edge or surface, i.e. apart from a simple and insulated metal. These materials are insulator in their bulk modes but are metal at the surface. Topological insulators are developed in two and three dimensions. Recently, compounds of the Bi2Se3 have attracted a huge attention because of existence of a Dirac cone in their surface state, having a suitable bandgap (0.3 eV), and easy santhesis. In this research, we investigate the properties of this material using density functional theory. The main focus is on bulk calculations and surface properties. The band structure of this material is studied in bulk mode without any consideration of spin - orbit interaction. Then a surface of this material is considered and its band structure and density of states are studied. The results show that the surface of this material has a Dirac cone. [ABSTRACT FROM AUTHOR]

[Display omitted] Highly site-specific growth of gold nanoparticles (AuNPs) on Bismuth Selenide (Bi 2 Se 3) hexagonal nanoplates was achieved by fine-tuning the growth kinetics of Au through controlling the coordination number of the Au ion in MBIA-Au3+ complex. With increasing concentration of MBIA, the increased amount and the coordination number of the MBIA-Au3+ complex results in the decrease of the reduction rate of Au. The slowed growth kinetics of Au allowed the recognition of the sites with different surface energy on the anisotropic Bi 2 Se 3 hexagonal nanoplates. As a result, the site-specific growth of AuNPs at the corner, the edge, and the surface of the Bi 2 Se 3 nanoplates were successfully achieved. This way of growth kinetic control was proven to be effective in constructing well-defined heterostructures with precise site-specificity and high purity of the product. This is helpful for the rational design and controlled synthesis of sophisticated hybrid nanostructures and would eventually promote their applications in various fields. [ABSTRACT FROM AUTHOR]

[Display omitted] Constructing heterostructures of two-dimensional (2D) materials is critical for boosting their photoelectric performances, enabling a promising route to meet the harsh requirement of next-generation optoelectronic devices. However, the practical application of currently-studied lateral and vertical heterostructures is usually limited by poor photocarrier generation and transport abilities, primarily due to their inherent imbalance of depletion region and interface area. To solve this obstacle, we herein report a novel 2D hybrid heterostructure of bismuth selenide/oxyselenide with the coexistence of lateral and vertical interfaces. The unique hybrid structure provides the heterostructure with a huge interface area and a wide depletion region for sufficient photocarrier generation and separation, significantly improving the overall optoelectronic performances of the device. Specifically, the resultant photodetectors exhibit a remarkably decreased dark current and ultrafast photoresponse rate (τ rise = 50 μs and τ decay = 20 μs). Moreover, our photodetector demonstrates outstanding image sensing capability for recording various complex patterns with high resolution over a wide spectral range from ultraviolet, visible to near-infrared regions. Our research provides a highly promising route for designing and fabricating novel geometries of 2D heterostructures to realize diverse photoelectric applications. [ABSTRACT FROM AUTHOR]

We show fledgling quantum spin Hall phase by the normal incidence of near-infrared circularly polarized radiation field on Bismuth Selenide doped with magnetic impurities. For this purpose, we start with a low-energy twodimensional, time-dependent Hamiltonian. The time dependence in the Hamiltonian arises due to the optical field describable by the associated gauge field. We make use of the Floquet theory in the high-frequency limit to investigate the system. The optical field tuneability leads to the emergence of the spin Hall phase, when intensity of the incident radiation is high, from the quantum anomalous Hall phase. Interestingly, the former phase is achievable here even in the presence of the magnetic impurities. [ABSTRACT FROM AUTHOR]

This paper continues the analysis of the results of experimental studies of resistive switching in a structure based on a bismuth selenide microcrystal (flake). It was demonstrated earlier by simulations that both the presence of several highly resistive states in the examined structure and the peculiarities of transitions to these states can be explained by the specific behavior of numerous conducting channels permeating the surface high-resistance (defective) layer. The sources of the nucleation of these channels are believed to be nanoprotrusions on the clamping control silver electrode embedded in the surface layer. In this study it is shown that volumetric inhomogeneities of the surface layer, namely nanoinclusions with higher conductivity, can serve as additional sources of the channels. Comparison of the simulation results confirms that the behavior of the channels forming near such inhomogeneities is similar to that of the channels growing from the metallic nanoprotrusions. [ABSTRACT FROM AUTHOR]

A single transistor preamplifier circuit was designed to facilitate electrical detection of mechanical oscillations in nanoelectromechanical systems (NEMSs) at low temperatures. The amplifier was integrated in the close vicinity of the nanowire inside the cryostat to minimize cabling load and interference. The function of the circuit was impedance conversion for current flow measurements in NEMSs with a high internal resistance. The circuit was tested to operate at temperatures as low as 5 K and demonstrated the ability to detect oscillations in double-clamped bismuth selenide nanowires upon excitation by a 0.1 MHz–10 MHz AC signal applied to a mechanically separated gate electrode. A strong resonance frequency dependency on temperature was observed. A relatively weak shift in the oscillation amplitude and resonance frequency was measured when a DC bias voltage was applied to the gate electrode at a constant temperature. [ABSTRACT FROM AUTHOR]

Bi2Se3, one of the most extensively studied topological insulators, has received significant attention, and abundant research has been dedicated to exploring its surface electronic properties. However, little attention has been given to its piezoelectric properties. Herein, we investigate the piezoelectric response in a five-layer Bi2Se3 nanosheet using scanning probe microscopy (SPM) techniques. The piezoelectricity of Bi2Se3 is characterized using both conventional piezoresponse force microscopy (PFM) and a sequential excitation scanning probe microscopy (SE-SPM) technique. To confirm the linear piezoelectricity of Bi2Se3 two-dimensional materials, measurements of point-wise linear and quadratic electromechanical responses are carried out. Furthermore, the presence of polarization and relaxation is confirmed through hysteresis loops. As expected, the Bi2Se3 nanosheet exhibits an electromechanical solid response. Due to the inevitable loss of translational symmetry at the crystal edge, the lattice of the odd-layer Bi2Se3 nanosheet is noncentrosymmetric, indicating its potential for linear piezoelectricity. This research holds promise for nanoelectromechanical systems (NEMS) applications and future nanogenerators. [ABSTRACT FROM AUTHOR]

In this work, a simple catalyst-free physical vapor deposition method is optimized by adjusting source material pressure and evaporation time for the reliable obtaining of freestanding nanoribbons with thicknesses below 15 nm. The optimum synthesis temperature, time and pressure were determined for an increased yield of ultrathin Bi2Se3 nanoribbons with thicknesses of 8–15 nm. Physical and electrical characterization of the synthesized Bi2Se3 nanoribbons with thicknesses below 15 nm revealed no degradation of properties of the nanoribbons, as well as the absence of the contribution of trivial bulk charge carriers to the total conductance of the nanoribbons. [ABSTRACT FROM AUTHOR]

Bismuth telluride (Bi 2 Te 3) is a widely used thermoelectric (TE) material in practical applications. However, it contains expensive and toxic tellurium, a promising TE material should include low-cost and non-toxic element. Bismuth selenide (Bi 2 Se 3) is similar to Bi 2 Te 3 in electronic and crystal structure. The electron effective mass of Bi 2 Se 3 is smaller than that of Bi 2 Te 3 , while its electrical transport performance is inferior to that of Bi 2 Te 3. Therefore, in this study, Cl and K co-doped Bi 2 Se 3 thermoelectric material with high density, low thermal conductivity, and excellent thermoelectric performance was prepared using KCl as the solvent. It is found that the effective electron mass and carrier concentration of the doped sample is effectively improved, which significantly increases the doped sample's electrical transport properties and ZT value. Finally, the Bi 2 Se 3 (KCl) 3.5 sample reached a maximum ZT value of 0.79 at 550 K, and the average ZT in the measured temperature range reached 0.45. [ABSTRACT FROM AUTHOR]

The topological insulator 2D Bi2Se3 is promising for electronic devices due to its unique electronic properties; however, it is challenging to prepare antioxidative nanosheets since Bi2Se3 is prone to oxidation. Surface passivation using ligand agents after Bi2Se3 exfoliation works well to protect the surface, but the process is time-consuming and technically challenging; a passivation agent that is stable under a highly biased potential is significant for in situ passivation of the Bi2Se3 surface. In this work, the roles of halide anions (Cl−, Br−, and I−) in respect of the chemical properties of synthetic Bi2Se3 nanosheets during electrochemical intercalated exfoliation were investigated to determine the antioxidation capacity. It was found that Bi2Se3 nanosheets prepared in a solution of tetrabutylammonium chloride (TBA+ and Cl−) have the best oxidation resistance via the surface bonding of Bi with Cl, which promotes obtaining better device stability. This work paves an avenue for adjusting the components of the electrolyte to further promote the stability of 2D Bi2Se3-nanosheet-based electronic devices. [ABSTRACT FROM AUTHOR]

Bi2Se3 nanoparticles were synthesized under greenery conditions by using economically viable desktop chemicals such as Bi(NO3)3, sodium selenite (Na2SeO3), EDTA, and L-Ascorbic acid. Prepared Bi2Se3 nanoparticles were characterized by UV-Vis Spectrophotometer, X-ray Diffraction, X-ray photoelectron spectroscopy (XPS), and Scanning electron microscopy. A prepared nanocatalyst is found to work efficiently for one-pot synthesis of diindolylmethanes from a set of indole and different aldehydes under solvent-free microwave environment and solvothermal conditions. Observed reaction times are enormously decreased when the reactions are conducted under a solvent-free microwave environment. [ABSTRACT FROM AUTHOR]

In this study, we utilized a successive ionic layer adsorption and reaction (SILAR) route to attach bismuth selenide (Bi 2 Se 3) nanoparticles on one dimensional (1D) cadmium sulfide nanowires (CdS NWs) at ambient temperature (27 °C) to design CdS@Bi 2 Se 3 core-shell nanostructure towards active electrode for supercapacitor application. To verify and explore the retrieved surface configuration, structural, elemental, compositional, and surface morphological investigations were performed. The designed CdS@Bi 2 Se 3 core-shell nanostructure not only offers the tremendous number of active areas, but also a continuous and quick one directional electron transport channels, demonstrating noticeable electrochemical performance with specific capacitance of 198 F g−1 (aerial capacitance 59.5 mF/cm2) with 80% cyclic retention @ 2000 cycles. Superior electrochemical activity was enhanced through the mutualistic involvement of Na+ ion insertion/extraction via non-stoichiometric bismuth selenide, which was well supported through electrochemical impedance (EIS) studies. [ABSTRACT FROM AUTHOR]

In this work, we present the generation of two distinct types of soliton pulses using a Bismuth Selenide (Bi2Se3) saturable absorber (SA) synthesized in our laboratory. The soliton pulses were generated in two different laser cavity configurations, resulting in two types of solitons: a soliton pulse with Kelly sidebands and a bunched soliton pulse with peak-dip sidebands. Both solitons operated at the fundamental repetition rate—23.3 MHz (for the soliton with Kelly sidebands) and 13 MHz (for the bunched soliton with peak-dip sidebands). We observed that the accumulation of nonlinear phase shift from the added single mode fiber (SMF) split the single soliton pulse into 44 pulses in a bunched oscillation envelope. At the same time, peak-dip sidebands were imposed on the bunched soliton spectrum due to constructive and destructive interferences between soliton pulse and dispersive waves. The measured pulse width for both solitons were 0.63 ps (for the soliton with Kelly sidebands) and 1.52 ps (for the bunched soliton with peak-dip sidebands), respectively. Our results demonstrate the potential of Bi2Se3 SAs in generating different types of soliton pulses, which could have potential applications in various areas of optical communication and spectroscopy. [ABSTRACT FROM AUTHOR]

An up to 25% power conversion efficiency and performance improvement of perovskite solar cells (PSCs) have made them promising products in photovoltaic technology. This study numerically investigates the light trapping and broadband light absorption enhancement of a PSC by introducing bismuth selenide (Bi2Se3) as shell material for Cu nanospheres (NSs) to achieve a "core/shell" configuration (Cu/Bi2Se3NSs) in the absorber layer of the PSC. The optimal values of Cu NS radius, Bi2Se3 thickness, periodicity of NSs, and the thickness of the absorber layer of PSC are equal to 40, 35, 172.5, and 410 nm, respectively. This structure has a photocurrent density (JL) of 33.01 mA cm−2 and a maximum normalized absorbed power (Pabs_total) of 0.89 compared to the bare PSC with JL = 21.8 mA cm−2 and Pabs_total = 0.87. The results indicate that the increase in the Bi2Se3 thickness up to 35 nm at a fixed Cu NS radius of 40 nm can enhance the absorption in the whole spectrum. However, this enhancement is greater at longer wavelengths. The extinction cross‐section is improved by about 3.5 times in comparison with the bare Cu NSs. The results for the PSC with Cu/Bi2Se3 NSs show a 51.3% absorption enhancement compared to the PSC without NSs. [ABSTRACT FROM AUTHOR]

The improvement of light trapping inside the active layer of perovskite solar cells (PSCs) was numerically investigated. The light absorption probability was improved by incorporating periodic arrays of mesoscopic electron‐transporting layer into the absorber layer (CH3NH3PbI3) of the PSCs. Accordingly, chalcopyrite (CuInSe2) and bismuth selenide (Bi2Se3) were introduced in the form of hexagonal pillars with an optimum radius of 35 nm and a height of 292 nm. It was found that the proposed PSCs can significantly extend the broadband light absorption from the visible spectrum to the near‐infrared (NIR) region compared to planar PSCs that have an identical active layer thickness. After optimization, the PSCs based on MP‐CuInSe2 and MP‐Bi2Se3 showed the best performance with an enhancement of respectively 32% and 54 % in the photocurrent density, (with values of 29.94 and 34.93 mA.cm−2), as compared to the planar PSC (with a photocurrent density of 22.69 mA.cm−2). This enhancement resulted from a more effective carrier transport due to the mesoscopic structures. [ABSTRACT FROM AUTHOR]

The overexpression of reactive oxygen and nitrogen species (RONS) in the colonic mucosa destroys the mucosa and its barrier, accelerating the occurrence of inflammatory bowel disease (IBD). The elimination of RONS from the inflammatory colon has proven effective in alleviating IBD. Although many nanoantioxidants have been developed, preparing robust and efficient nano-antioxidants remains challenging. Herein, by modifying bismuth selenide (Bi 2 Se 3) nanodiscs with polyvinylpyrrolidone (PVP), a multifunctional nanozyme based on 2D nanomaterials was developed for the treatment of IBD. By eliminating multiple RONS, such as hydroxyl radicals (• OH), superoxide anions (O 2 −•), nitric oxide (NO), and Bi 2 Se 3 nanodiscs enhanced cellular survival after H 2 O 2 stimulation. As evidenced by colonic injury, reduced body weight, spleen index, and proinflammatory cytokine levels in mice, RONS clearance alleviated intestinal inflammation in a prevention and delay model of acute colitis. 16S rDNA amplicon sequencing reveals that Bi 2 Se 3 nanodiscs had the potential to regulate intestinal flora, increase the proportion of Firmicutes to Bacteroidetes, inhibit Proteobacteria bacteria, and restore intestinal homeostasis. This study highlights the use of Bi 2 Se 3 nanodiscs with excellent biocompatibility, multienzyme functionality, and RONS scavenging ability as treatments for IBD without apparent adverse effects. RONS were efficiently scavenged by Bi 2 Se 3 nanodiscs. Bi 2 Se 3 nanodiscs could be as a promising and potentially safe theraeputic agent for IBD. The gut microbiota could be modulated by Bi 2 Se 3 nanodiscs. [Display omitted] [ABSTRACT FROM AUTHOR]

Localized surface plasmon resonance (LSPR) is the cause of the photo-thermal effect observed in topological insulator (TI) bismuth selenide (Bi2Se3) nanoparticles. These plasmonic properties, which are thought to be caused by its particular topological surface state (TSS), make the material interesting for application in the field of medical diagnosis and therapy. However, to be applied, the nanoparticles have to be coated with a protective surface layer, which prevents agglomeration and dissolution in the physiological medium. In this work, we investigated the possibility of using silica as a biocompatible coating for Bi2Se3 nanoparticles, instead of the commonly used ethylene-glycol, which, as is presented in this work, is not biocompatible and alters/masks the optical properties of TI. We successfully prepared Bi2Se3 nanoparticles coated with different silica layer thicknesses. Such nanoparticles, except those with a thick, ≈200 nm silica layer, retained their optical properties. Compared to ethylene-glycol coated nanoparticles, these silica coated nanoparticles displayed an improved photo-thermal conversion, which increased with the increasing thickness of the silica layer. To reach the desired temperatures, a 10–100 times lower concentration of photo-thermal nanoparticles was needed. In vitro experiments on erythrocytes and HeLa cells showed that, unlike ethylene glycol coated nanoparticles, silica coated nanoparticles are biocompatible. [ABSTRACT FROM AUTHOR]

Bismuth selenide (Bi2Se3) is a novel topological insulator that is promising for broad optical absorption materials on the basis of its large bulk band and well-defined single Dirac cone. Herein, few-layer Bi2Se3 nanoplates of different sizes have been successfully synthesized via the solvothermal method. We present our discovery of optical properties on homojunction Bi2Se3 nanoplates with FTIR measurements. The interface of homojunction Bi2Se3 nanoplates demonstrates an interesting optical modulation in the near-infrared region in contrast to individual bulk Bi2Se3 and other reported 2D hetero-structure materials. It was validated that the unexpected behavior was attributed to the interface between variously stacked nanoplates and its unique zero-wave anti-reflection properties. Our experimental results provide evidence of the Bi2Se3 nanoplate possess high optical absorption in the near-infrared range, promising for photothermal and optical diagnostic therapy application. [ABSTRACT FROM AUTHOR]

Abstract The energy dispersion of the unoccupied Dirac bands of the topological insulator Bi2Se3 has been studied up to large parallel momenta and intermediate state energies using a setup for laser‐based time‐resolved momentum microscopy with 6 eV probe‐photons. A strongly momentum‐dependent evolution of the topologically protected Dirac states into a conduction band resonance is observed, highlighting the anisotropy dictated by the symmetry of the surface. The results are in remarkable agreement with the theoretical surface spectrum obtained from a GW‐corrected tight‐binding model, suggesting the validity of the approach in the prediction of the quasiparticle excitation spectrum of large systems with non‐trivial topology. After photoexcitation with 0.97 eV photons, assigned to a bulk valence band‐conduction band transition, the out‐of‐equilibrium population of the surface state evolves on a multi‐picosecond time scale, in agreement with a simple thermodynamical model with a fixed number of particles, suggesting a significant decoupling between bulk and surface states.

Electrical explosion, characterized by ultrafast atomization and quenching rate (dT/dt ≈ 1010–1012 K s–1) of the sample, is a unique approach for "one‐step" synthesis of nanomaterials. Experiments are carried out with layered graphite and Bi2Se3 under the action of electrical explosion in a confined reaction tube. High‐speed photography and electrophysical diagnostics are applied to characterize dynamic processes. SEM and EDS are used to characterize surface micro‐morphology of reaction products. The layered materials are first exfoliated to thin nanosheets/nanocrystals by shock waves and turbulent flow of the explosion. As the ionized explosion products (>10 000 K) contacts the sample, intense heat transfer happens, simultaneously atomizing the sample and quenching the plasmas. As a result, nanoparticles grow on the surface of thin sheets, forming "dot‐sheet" structure. The size distribution of the nanoparticles typically ranges from 10 to 100 nm, following Log‐normal distribution. The dotted graphite nanosheets gather together and form a stacked/cabbage‐like structure. By contrast, Bi2Se3 case accompanies with chemical reactions, causing surface corrosion and showing more possibilities: nanocrystals and nanotubes growth on different areas of the sample. [ABSTRACT FROM AUTHOR]

In spite of the explosive rise of research on memristive switching, more improvements in tunability, versatility, and heterointegration are required through the discovery and application of novel materials. Herein, we report resistance switching in nanothick two-dimensional (2D) crystals of bismuth selenium (BiSe). The BiSe devices exhibit nonvolatile bipolar resistance switching, volatile switching, and electrical bistable behavior in different conditions. The different memristive behavior of BiSe devices may be related to the concentration of Bi ions in this Bi-rich structure, which directly affects the capability of filaments forming. Furthermore, the external mechanical strain is applied in modulation of multi-layer BiSe devices. The memristive BiSe devices show a large on/off ratio of ∼ 104 and retention time of ∼ 104 s. The discovery of memristive switching behavior in multi-layer BiSe is attributed to the forming of Bi filaments. The resistance switching behavior in multi-layer BiSe demonstrates the potential application in the flexible memories and functional integrated devices. [ABSTRACT FROM AUTHOR]

The previously proposed critical field model is applied to analyze the results of experimental studies of resistive switchings in the structure based on bismuth selenide microcrystal (flake). This structure has several highly resistive states. Moreover, the switching voltages are in the range from –0.8 to +0.8 V. As in other studies devoted to memristive structures based on bismuth selenide, in the analysis, changes in the resistive state of the considered structure are assumed to be associated with the formation or destruction of conducting channels through a high-resistance surface layer. In addition, it is suggested that the main sources of conducting channels in this structure can be numerous metal nanoprotrusions embedded in the surface layer in the zone of its contact with the clamping control electrode (thin tip of a silver wire). The modeling shows that the accepted assumptions make it possible to explain both the presence of several highly resistive states in the studied structure and the features of transitions to these states. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bimetallic 1Bi1Fe-Se@NF electrode shows nanoflower-like morphology. • A composite structure exists in 1Bi1Fe-Se@NF with high surface area and low bandgap. • 1Bi1Fe-Se@NF shows low overpotentials for HER (53 mV) and OER (230 mV) @10 mA cm−2. • The 1Bi1Fe-Se@NF (+,−) electrolyser needs ∼1.52 V @10 mA cm−2 for operation. • Symmetric electrolyser maintains low voltage after running for 100 h @ 50 mA cm−2. The current study presents a freestanding bifunctional electrocatalyst comprising hierarchically assembled Bi/Fe-based selenide with a nanoflower-like morphology on Ni foam for water electrolysis application. The impact of systematically adding Fe ions to Bi 2 Se 3 on the phase and morphology is elaborately discussed. It is shown that tuning the Bi/Fe molar ratio governs the phase, electronic bandgap, and morphology, driven by the evolution of hetero-interfacial chemistry. The existence of multivalent metal ions, lattice defects, and an extended surface area remarkably improves the electrocatalytic activity. The optimized nanoflower-like composite electrode (1Bi1Fe-Se@NF) exhibits robust electrocatalytic efficacy with extremely low overpotentials of ∼53 mV and ∼230 mV at 10 mA cm−2 for hydrogen and oxygen evolution reactions, respectively. The symmetrical alkaline electrolyser, utilizing 1Bi1Fe-Se@NF electrodes (+,−), operates at a cell voltage of ∼1.52 V at 10 mA cm−2, lower than the device equipped with commercial Pt/C@NF (-) and RuO 2 @NF (+) (∼1.57 V). Even after 100 h of operation at 50 mA cm−2, the symmetrical cell maintains a stable voltage, highlighting the outstanding bifunctional catalytic activities of noble metal-free 1Bi1Fe-Se@NF for overall water electrolysis. [ABSTRACT FROM AUTHOR]

Bismuth selenide-based nanomaterials are introduced as theranostic agents, primarily enhancing their antimicrobial, anti-cancerous, antitumor, and antioxidant properties. Pure Bi 2 Se 3 and V doped Bi 2 Se 3 with V = 0.07 g, 0.12 g, and 0.15 g were synthesized by using Sol-gel Technique. X-ray Diffraction (XRD) patterns demonstrated that the manufactured samples were crystalline in nature having rhombohedral structure. The average crystallite sizes of V x Bi 2-x S 3 were calculated by Scherrer formula in the range (24.9–11.0 nm). The average crystallite size reduced as doping concentrations increased (0–0.15 g). The FTIR (Fourier transform infrared) spectra confirms that the peaks corresponds to 900–600 cm−1 indicates Bi–Se bond stretching, whereas vibrations exhibit peaks between 704 cm−1 - 830 cm−1 in doped samples correspond to V–O bond. UV–Visible analysis shows that the band gap of doped Bi 2 Se 3 increased from (2.57 eV–2.90 eV) having standard error 0.02, 0.01, 0.02, and 0.02 respectively as the concentrations of doping increased (0.0–0.15 g), respectively. SEM (Scanning electron microscopy) study of pure Bi 2 Se 3 showed nanosized particles, and for doped, a clear change in morphology occurred with the particles tending to agglomerate. EDAX also confirms the purity of synthesized samples. XPS analysis confirms the presence of Bi, Se and Vanadium along with chemisorbed oxygen. Antibacterial potential of synthesized samples was analyzed against Pseudomonas, Escherichia coli and cocci bacteria, which showed that the vanadium doped bismuth selenide has greater zone of inhibition than undoped bismuth selenide. Pseudomonas shows more ZOI (Zone of Inhibition) than E.coli and cocci. The maximum inhibition zone was 25 mm against Pseudomonas for V 0.15 Bi 1.85 Se 3. The In-Vivo toxicity experiment was also applied on mice's (Swiss Albino) with a higher dosage of 20 mg per kg of the prepared doped sample. The blood samples were collected and examined after 3rd, 7th, 14th and 21st day of treatment. The entire treatment does not cause any severe damage to mice. An evaluation of a p-value based on hematological and biochemical data was non-significant this ensures that vanadium doped Bi 2 Se 3 nanoparticles are non-toxic and biocompatible. This work proves that V-doped Bi 2 Se 3 is good for further study in many other Applications in the biomedical field, such as photo thermal therapy, imaging etc. • Nanomaterials have received attention due to their notable biological properties and applications in biomedicine. • Bismuth, selenium and Vanadium have remarkable biomedical Applications. • Antibacterial activity of Vanadium doped Bismuth selenide showed promising results. • Vanadium doped selenide are not toxic to affect the functioning body. [ABSTRACT FROM AUTHOR]

Van der Waals and wide-bandgap materials-based heterostructures have garnered substantial attention in developing self-powered broadband photodetectors owing to their exceptional photovoltaic capabilities. These materials also hold great potential for breakthroughs in optoelectronics. However, limitations to low selectivity constrain the potential of heterostructures-based broadband detectors. Here, we design wavelength-selective polarity switching in a heterostructure photodetector consisting of bismuth selenide (Bi 2 Se 3) and gallium nitride (GaN). The analysis revealed a positive photocurrent under ultraviolet-C illumination to visible wavelength, whereas a negative photocurrent under infrared wavelengths at zero applied bias. The exposure to distinct optical wavelengths leads to an inversion in the electric field polarity across the junction, resulting in polarity switching. The fabricated Bi 2 Se 3 /GaN self-powered ultra-broadband photonic device demonstrates a peak photoresponsivity of 584 mAW−1 (−297 mAW−1) at 355 nm (1405 nm) wavelength illumination and can detect weak signals up to 650 femto-watt. Our strategy revealed alternative avenues for developing polarity-switchable, self-powered ultra-broadband photodetectors, offering a first step towards creating wavelength-adaptable sensors for future applications. [Display omitted] • Novel self-powered photodetector using a heterostructure of Bi 2 Se 3 and GaN. • Wavelength-selective polarity switching (Deep UV to IR) self powered photodetector. • Exhibits a peak photoresponsivity of 584 mAW−1 @ 355 nm & −297 mAW−1 @ 1405 nm under self-powered mode. • Dedetect weak optical signals as low as 650 femto-watt. [ABSTRACT FROM AUTHOR]

The ability to control heat flux at the nanoscale opens up numerous exciting possibilities in modern electronics and the field of information processing. In this research, we propose a design with the focus on achieving efficient thermal rectification at moderate gap and relatively low temperature. This study centers on near-field thermal radiation between temperature dependent indium antimonide (InSb) and silicon carbide (3C-SiC) coated with bismuth selenide (Bi 2 Se 3). Our investigation sheds light on the critical role played by the Bi 2 Se 3 layer in enhancing various key parameters, including the net radiative flux, and thermal rectification efficiency (η). We achieved a substantial improvement in the η of a near-field radiative thermal rectifier (NFRTR) due to the presence of the Bi 2 Se 3 sheet. This enhancement is contingent on factors such as the Fermi energy (E f) of Bi 2 Se 3 , emitter temperature, and the vacuum gap (d). Our study culminated in the identification of an optimal design, achieving an impressive η of 75% at an emitter temperature (T H) of 350 K, with vacuum gap (d) set to 20 nm. Furthermore, increasing T H to 500 K resulted in even more promising outcomes, with the highest η reaching 93%. The need for operating the optimized device at moderate temperatures is to strike a balance between efficiency, safety, cost-effectiveness, and material compatibility. These findings represent a significant step forward in the development of efficient Bi 2 Se 3 -based NFRTRs, paving the way for future applications in thermal management, energy conversion systems, and thermal logic gates. [Display omitted] • The use of materials with tailored EM response is important for the design of an efficient thermal rectifier. • The optical parameters of the materials constituting a thermal rectifier should be temperature dependent: an important prerequisite. • The need to explore new materials that can function as efficient thermal rectifiers with moderate gap and low temperature is a subject of active research. • We introduce a matrix method for deriving SPP relationship for a multilayer systems • We proposed the use of bismuth selenide (Bi 2 Se 3) by leveraging on its thermal tunability which is a key factor in mediating thermal radiation. • Combining Bi 2 Se 3 with temperature dependent materials leads to an efficient thermal rectifier. [ABSTRACT FROM AUTHOR]

A single transistor preamplifier circuit was designed to facilitate electrical detection of mechanical oscillations in nanoelectromechanical systems (NEMSs) at low temperatures. The amplifier was integrated in the close vicinity of the nanowire inside the cryostat to minimize cabling load and interference. The function of the circuit was impedance conversion for current flow measurements in NEMSs with a high internal resistance. The circuit was tested to operate at temperatures as low as 5 K and demonstrated the ability to detect oscillations in double-clamped bismuth selenide nanowires upon excitation by a 0.1 MHz–10 MHz AC signal applied to a mechanically separated gate electrode. A strong resonance frequency dependency on temperature was observed. A relatively weak shift in the oscillation amplitude and resonance frequency was measured when a DC bias voltage was applied to the gate electrode at a constant temperature.

Bi2Se3, one of the most extensively studied topological insulators, has received significant attention, and abundant research has been dedicated to exploring its surface electronic properties. However, little attention has been given to its piezoelectric properties. Herein, we investigate the piezoelectric response in a five-layer Bi2Se3 nanosheet using scanning probe microscopy (SPM) techniques. The piezoelectricity of Bi2Se3 is characterized using both conventional piezoresponse force microscopy (PFM) and a sequential excitation scanning probe microscopy (SE-SPM) technique. To confirm the linear piezoelectricity of Bi2Se3 two-dimensional materials, measurements of point-wise linear and quadratic electromechanical responses are carried out. Furthermore, the presence of polarization and relaxation is confirmed through hysteresis loops. As expected, the Bi2Se3 nanosheet exhibits an electromechanical solid response. Due to the inevitable loss of translational symmetry at the crystal edge, the lattice of the odd-layer Bi2Se3 nanosheet is noncentrosymmetric, indicating its potential for linear piezoelectricity. This research holds promise for nanoelectromechanical systems (NEMS) applications and future nanogenerators.

In this work, a simple catalyst-free physical vapor deposition method is optimized by adjusting source material pressure and evaporation time for the reliable obtaining of freestanding nanoribbons with thicknesses below 15 nm. The optimum synthesis temperature, time and pressure were determined for an increased yield of ultrathin Bi2Se3 nanoribbons with thicknesses of 8–15 nm. Physical and electrical characterization of the synthesized Bi2Se3 nanoribbons with thicknesses below 15 nm revealed no degradation of properties of the nanoribbons, as well as the absence of the contribution of trivial bulk charge carriers to the total conductance of the nanoribbons.

Two-dimensional topological insulator bismuth selenide (Bi2Se3) nanosheets (NSs) embedded in poly-methyl methacrylate (PMMA) are employed for the first time for the resistive switching (RS) application. Hexagonal 2D Bi2Se3 NSs are synthesized by a simple solvothermal method and combine with PMMA at different weight percentages of 2D Bi2Se3. Field emission scanning electron microscopy and transmission electron microscopy along with other characterizations such as X-ray photoelectron spectroscopy and Raman spectroscopy were performed for the characterization of Bi2Se3@PMMA hybrid system. The composite was deposited on a transparent, flexible polyethylene terephthalate substrate to form Ag/Bi2Se3@PMMA/indium doped tin oxide memory cell. I-V characteristics of the device revealed a stable and non-volatile memory effect. The device shows a significantly high resistance (RHRS/RLRS) ratio, more than 103, high retention time (more than 9000 s) with high reproducibility over a large number of (105) ac cycles. From the experimental data, RS performances are explained by using a charge trapping–detrapping mechanism. Owing to the increasing interest in flexible electronics, bending tests are carried out at various bending diameters (10–30 mm) to show the mechanical robustness of the proposed device. [ABSTRACT FROM AUTHOR]

In the present report, we have reported the bismuth selenide (Bi2Se3) thin films for solar cell application. The synthesis of bismuth selenide (Bi2Se3) thin film by using modified chemical bath deposition i. e. arrested precipitation technique (APT). The Physico‐chemical properties of synthesized Bi2Se3 thin films are studied as a function of surfactants. The XRD patterns confirm the nanocrystalline nature. The SEM images reveal morphological transitions from fibrous reticulate structure to spongy balls‐like structure. The compositional analysis confirms bismuth and selenium in good stiochiometry. Optical studies show presence of a absorption in the visible range with a band gap in the range of 1.5 eV to 1.9 eV. All these results reveal that surfactant‐assisted Bi2Se3 thin film is a better candidate for PEC performance. [ABSTRACT FROM AUTHOR]

A simple sol-gel approach was used to synthesize Cu doped Bismuth Selenide nanoparticles denoted as Cu x Bi 2-x Se 3 (x = 0.1, 0.2), in order to comprehend the effect of Cu-dopant on the photocatalytic and antibacterial activity of Bismuth Selenide. The structural properties of prepared samples were investigated by the XRD technique and results showed the formation of hexagonal Cu x Bi 2-x Se 3 (x = 0.1, 0.2). The average crystallite size of Cu x Bi 2-x Se 3 was found to increase from 39 nm to 42 nm with the increase in the concentration of Cu ions. Atomic force microscopy (AFM) was used to confirm the morphology and particle size of prepared samples. Photoluminescence (PL) studies revealed the decrease in band gap from 1.66 eV to 1.61 eV for Cu 0.1 Bi 1.9 Se 3 and Cu 0.2 Bi 1.8 Se 3 , respectively. The Raman spectra of Cu x Bi 2-x Se 3 (x = 0.1, 0.2) showed two vibrational modes at 130 cm−1 and 170 cm−1. The photocatalytic performance of prepared nanoparticles was evaluated by the removal of methyl blue (MB) and malachite green (MG), under natural sunlight. Cu doped Bismuth Selenide Cu 0.2 Bi 1.8 Se 3 exhibited higher photocatalytic activity as compared to Cu 0.1 Bi 1.9 Se 3 and undoped Bismuth Selenide with the 97% and 99% degradation of MB and MG, respectively. Hence, Cu doping proved an efficient way to enhance the photocatalytic response of Bismuth Selenide. Through the antibacterial activity, it was further disclosed that the Cu doped samples had better inhibition zones than undoped Bismuth Selenide. The maximum inhibition zone (29 mm) was observed at optimum doping concentration for Cu 0.2 Bi 1.8 Se 3. From the results, it can be deduced that Cu 0.2 Bi 1.8 Se 3 can be as effective photocatalytic and antibacterial agent to treat water pollution. [ABSTRACT FROM AUTHOR]

The performances of rechargeable batteries are strongly affected by the operating environmental temperature. In particular, low temperatures (e.g., ≤0 °C) are detrimental to efficient cell cycling. To circumvent this issue, we propose a few-layer Bi2Se3 (a topological insulator) as cathode material for Zn metal batteries. When the few-layer Bi2Se3 is used in combination with an anti-freeze hydrogel electrolyte, the capacity delivered by the cell at −20 °C and 1 A g−1 is 1.3 larger than the capacity at 25 °C for the same specific current. Also, at 0 °C the Zn | |few-layer Bi2Se3 cell shows capacity retention of 94.6% after 2000 cycles at 1 A g−1. This behaviour is related to the fact that the Zn-ion uptake in the few-layer Bi2Se3 is higher at low temperatures, e.g., almost four Zn2+ at 25 °C and six Zn2+ at −20 °C. We demonstrate that the unusual performance improvements at low temperatures are only achievable with the few-layer Bi2Se3 rather than bulk Bi2Se3. We also show that the favourable low-temperature conductivity and ion diffusion capability of few-layer Bi2Se3 are linked with the presence of topological surface states and weaker lattice vibrations, respectively. The performances of rechargeable batteries are detrimentally affected by low temperatures (e.g., < 0 °C). Here, the authors report a few-layer Bi2Se3 material capable of improving battery cycling performances when operational temperatures are shifted from +25 °C to −20 °C. [ABSTRACT FROM AUTHOR]

We discuss experimental and theoretical studies of the generation of the third terahertz (THz) frequency harmonic in thin films of Bi2Se3 and Bi2-xSbxTe3-ySey (BSTS) topological insulators (TIs) and the generation of THz radiation in photoconductive antennas based on the TI films. The experimental results, supported by the developed kinetic theory of third harmonic generation, show that the frequency conversion in TIs is highly efficient because of the linear energy spectrum of the surface carriers and fast energy dissipation. In particular, the dependence of the third harmonic field on the pump field remains cubic up to the pump fields of 100 kV/cm. The generation of THz radiation in TI-based antennas is obtained and described for the pump, with the energy of photons corresponding to the electron transitions to higher conduction bands. Our findings open up possibilities for advancing TI-based films into THz photonics as efficient THz wave generators and frequency converters. [ABSTRACT FROM AUTHOR]

As a promising topological insulator, two-dimensional (2D) bismuth selenide (Bi2Se3) attracts extensive research interest. Controllable surface doping of layered Bi2Se3 becomes a crucial issue for the relevant applications. Here, we propose an efficient method for the chemical thinning and surface doping of layered Bi2Se3, forming Se/Bi2Se3 heterostructures with tunable thickness ranging from a few nanometers to hundreds of nanometers. The thickness can be regulated by varying the reaction time and large-size few-layer Bi2Se3 sheets can be obtained. Different from previous liquid-exfoliation methods that require complex reaction process, in-situ and thickness-controllable exfoliation of large-size layered Bi2Se3 can be realized via the developed method. Additionally, the formation of Se nanomeshes coated on the Bi2Se3 sheets remarkably enhance the intensity of Raman vibration peaks, indicating that this method can be used for surface-enhanced Raman scattering. The proposed chemical thinning and surface-doping method is expected to be extended to other bulk-layered materials for high-efficient preparation of 2D heterostructures. [ABSTRACT FROM AUTHOR]