Bi2Se3 Nanosheets Research Articles

Two-Dimensional Bi2Se3 Nanosheets Synthesis for Efficient Electrocatalytic Production of Ammonia from Nitrate

Ammonia (NH3), a critical component for various industries, is produced through the Haber-Bosch process, which, despite its importance, is a significant source of carbon emissions and operates on a centralized model, emphasizing the need for innovative solutions to decarbonize and decentralize its production. Electrochemical nitrate (NO3–) reduction to NH3 presents a promising alternative to the Haber-Bosch process for NH3 synthesis, with the added advantage of transforming waste into a valuable resource while mitigating water pollution concerns. However, achieving a well-defined active center and catalytic selectivity in the electrochemically driven reaction remains a significant challenge. In this study, we successfully fabricated a highly selective and active 2D Bi2Se3 catalyst, which demonstrated better performance in reducing NO3– to NH3 with a Faradaic efficiency (FE) of approximately 80% (−0.3V (RHE)) and a significant yield rate of 45mgh−1mgcat−1 (0.46 mmolh−1cm−2). Furthermore, the fabricated material exhibited exceptional stability and durability, maintaining a high NO3– reduction of 80% FE even after 10 consecutive cycles of extended use and continuous operation, demonstrating its remarkable resilience and reliability. Our findings show that the prepared catalyst selectively promotes the electrochemical reduction of NO3– to NH3 while suppressing the competing hydrogen evolution reaction (HER). The charge density profile indicates a pronounced charge localization around the Se atoms, implying that the Se active sites in the 2D Bi2Se3 catalyst act as the active center for the NO3– reduction mechanism, playing a crucial role in facilitating the reaction kinetics.

Effective Identification and Highly Sensitive Quantification of Fructo-oligosaccharide Isomers with Bi2Se3 Nanosheet-Assisted Laser Desorption Ionization Mass Spectrometry.

The growing interest in fructo-oligosaccharides (FOSs) necessitates the effective monitoring of product quality. Identifying and quantifying FOS isomers from the same sources are challenging. Here, we report a new method using Bi2Se3 nanosheets as the matrix for matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS), achieving effective differentiation of oligosaccharide isomers through MALDI-MS/MS. Notably, four isomers of pentasaccharides and two isomers of heptasaccharides were successfully identified, with a remarkably low limit of detection of 0.06 pmol. Our approach enabled the specific quantification of 1F-fructofuranosylnystose in commercial FOS products, positioning it as a promising tool for oligosaccharide isomer quantification in nutritional food products. Furthermore, this technique facilitates the rapid and sensitive detection of various saccharides and a wide range of other small molecules with enhanced signal intensities and improved reproducibility. Overall, it facilitates the rapid, selective, and sensitive detection of various saccharides and other small molecules, enhancing analytical chemistry and food science applications.

Tailored thickness engineering of Bi2Se3 nanosheets for superior cathodic performance in aqueous zinc-ion batteries

Bi2Se3 is considered a suitable cathode material for zinc-ion batteries (ZIBs) because of its high conductivity and large layer spacing. Herein, Bi2Se3 nanosheets with varying thicknesses are successfully synthesized using a one-step solvothermal process with adding different amounts of ethylenediamine. The introduction of ethylenediamine reduces the thickness of Bi2Se3 from 250 nm to 22.7 nm. The thin structure exposes more active sites and shortens ion transport paths. Therefore, the optimized Bi2Se3 nanosheet exhibits outstanding specific capacity (410 mA h g−1 at 0.2 A/g), high-rate performance (230 mA h g−1 at 5 A/g), and remarkable cycling stability (82.3 % capacity retention after 1200 cycles at 5 A/g). Furthermore, an in-depth exploration of cathodes during cycling is conducted to investigate the charge/discharge mechanism. A dynamic phase transition from Bi2Se3 to BiSe, accompanied by nanosheet exfoliation, is observed during the initial few cycles, designating BiSe as the primary active material. Moreover, an additional redox reaction involving multiple electrons has been proposed. This study offers a valuable guidance for utilizing Bi2Se3 as a cathode in ZIBs.

Bi2Se3 nanosheets prepared by solvothermal method for high performance NIR photodetector

Bismuth selenide (Bi2Se3) nanosheets, a member of the AV-BVI (A = Sb, Bi, B = S, Se, Te) family of metal chalcogenide semiconductor materials, have a large surface area, a tunable bandgap that is dependent on the thickness of the atomic layer, and potential applications in photocatalysis, photothermal therapy, and photodetectors, among other fields. Here, we describe the synthesis of Bi2Se3 nanosheets using a simple solvothermal method, resulting in a smooth surface and a well-crystalline structure. The XRD results indicate that the Bi2Se3 nanosheets belong to the hexagonal crystal structure, with lattice constants of a = 0.4140 nm, b = 0.4140 nm, and c = 2.8636 nm. Bi2Se3 nanosheet photodetectors, which have a Schottky contact between the nanosheets and the electrodes, exhibit a notable light response to an 850 nm laser. The device displays a switch ratio of 50 when operated at a voltage of 0.6 V and an irradiance of 2.87 W/cm2 (@ 850 nm). The switching speed of the device was measured in terms of rise and decay times, measured to be 126 ms and 85 ms respectively. It is evident from the obtained results that high performance nanoscale photodetectors can be made efficiently from 2D Bi2Se3 nanosheets.

Dynamic Reconstruction of Two-Dimensional Defective Bi Nanosheets for Efficient Electrocatalytic Urea Synthesis.

Catalyst surface dynamics drive the generation of active species for electrocatalytic reactions. Yet, the understanding of dominant site formation and reaction mechanisms is limited. In this study, we thoroughly investigate the dynamic reconstruction of two-dimensional defective Bi nanosheets from exfoliated Bi2Se3 nanosheets under electrochemical CO2 and nitrate (NO3 -) reduction conditions. The ultrathin Bi2Se3 nanosheets obtained by NaBH4-assisted cryo-mediated liquid-phase exfoliation are more easily reduced and reconstructed to Bi nanosheets with high-density grain boundaries (GBs; GB-rich Bi). The reconstructed GB-rich Bi catalyst affords a remarkable yield rate of 4.6 mmol h-1 mgcat. -1 and Faradaic efficiency of 32 % for urea production at -0.40 V vs. RHE. Notably, this yield rate is 2 and 8.2 times higher than those of the low-GB Bi and bulk Bi catalysts, respectively. Theoretical analysis demonstrates that the GB sites significantly reduce the *CO and *NH2 intermediate formation energy and C-N coupling energy barrier, enabling selective urea electrosynthesis on the GB-rich Bi catalyst. This work will trigger further research into the structure-activity interplay in dynamic processes using in situ techniques.

Dynamic Reconstruction of Two‐Dimensional Defective Bi Nanosheets for Efficient Electrocatalytic Urea Synthesis

AbstractAbstract:Catalyst surface dynamics drive the generation of active species for electrocatalytic reactions. Yet, the understanding of dominant site formation and reaction mechanisms is limited. In this study, we thoroughly investigate the dynamic reconstruction of two‐dimensional defective Bi nanosheets from exfoliated Bi2Se3 nanosheets under electrochemical CO2 and nitrate (NO3−) reduction conditions. The ultrathin Bi2Se3 nanosheets obtained by NaBH4‐assisted cryo‐mediated liquid‐phase exfoliation are more easily reduced and reconstructed to Bi nanosheets with high‐density grain boundaries (GBs; GB‐rich Bi). The reconstructed GB‐rich Bi catalyst affords a remarkable yield rate of 4.6 mmol h−1 mgcat.−1 and Faradaic efficiency of 32 % for urea production at −0.40 V vs. RHE. Notably, this yield rate is 2 and 8.2 times higher than those of the low‐GB Bi and bulk Bi catalysts, respectively. Theoretical analysis demonstrates that the GB sites significantly reduce the *CO and *NH2 intermediate formation energy and C−N coupling energy barrier, enabling selective urea electrosynthesis on the GB‐rich Bi catalyst. This work will trigger further research into the structure‐activity interplay in dynamic processes using in situ techniques.

Experimental Demonstration of Topological Catalysis for CO2 Electroreduction.

The past decade has witnessed substantial progress in understanding nontrivial band topology and discovering exotic topological materials in condensed-matter physics. Recently, topological physics has been further extended to the chemistry discipline, leading to the emergence of topological catalysis. In principle, the topological effect is detectable in catalytic reactions, but no conclusive evidence has been reported yet. Herein, by precisely manipulating the topological surface state (TSS) of Bi2Se3 nanosheets through thickness control and the application of a magnetic field, we provide direct experimental evidence to illustrate topological catalysis for CO2 electroreduction. With and without the cooperation of TSS, CO2 is mainly reduced into liquid fuels (HCOOH and H2C2O4) and CO, exhibiting high (up to 90% at -1.1 V versus reversible hydrogen electrode) and low Faradaic efficiency (FE), respectively. Theoretically, the product and FE difference can be attributed to the TSS-regulated adsorption of key intermediates and the reduced barrier of the potential-determining step. Our work demonstrates the inherent correlation between band topology and electrocatalysis, paving a new avenue for designing high-performance catalysts.

Scalable fabrication of two-dimensional Bi2Se3 for high-performance supercapacitors

Although having an advantageous charge–discharge rate, supercapacitors, in terms of energy density, are still dwarfed by their battery counterparts, thereby hindering their industrial use. Two-dimensional (2D) Bi2Se3, which is characterized by high electrical conductivity, possesses a large theoretical specific capacity that has not been experimentally realized. In this study, we employed scalable electrochemical exfoliation to fabricate high-quality Bi2Se3 nanosheets with a yield of over 95 %. These nanosheets were then applied as anode materials with the hitherto highest specific capacitance of 662.5 F/g at 1A/g to assemble asymmetric supercapacitors (ASCs) of Bi2Se3//NiCo2S4. The supercapacitors demonstrated an extraordinary energy density of 48 Wh/kg at a power density of 800 W/kg and efficiently drove devices such as perovskite-LEDs. This study reveals the huge potential of 2D Bi2Se3 as an efficient supercapacitor electrode via a primary Faradaic pseudocapacitive storage mechanism. The scalable production of this material is expected to stimulate its widespread and practical use.

Tailoring Bi2Se3 Topological Insulator for Visible-NIR Photodetectors with Schottky Contacts Using Liquid Phase Exfoliation.

Layered semiconductors of the V-VI group have attracted considerable attention in optoelectronic applications owing to their atomically thin structures. They offer thickness-dependent optical and electronic properties, promising ultrafast response time, and high sensitivity. Compared to the bulk, 2D bismuth selenide (Bi2Se3) is recently considered a highly promising material. In this study, 2D nanosheets are synthesized by prolonged sonication in two different solvents, such as N-methyl-2-pyrrolidone (NMP) and chitosan-acetic acid solution (CS-HAc), using the liquid-phase exfoliation (LPE) method. X-ray diffraction confirms the amorphous nature of exfoliated 2D nanosheets with maximum peak intensity at the same position (015) crystal plane as that obtained in its bulk counterpart. SEM confirms the thin 2D nanosheet-like morphology. Successful exfoliation of Bi2Se3 nanosheets up to five layers is achieved using CS-HAc solvent. The as-synthesized 2D nanosheets in different solvents are employed to fabricate the photodetector. At minimum selected power density, the photodetector fabricated using exfoliated ultrathin 2D nanosheets exhibits the highest range of responsivity, varying from 15 to 2.5 mA/W, and detectivity ranging from 2.83 × 109 to 6.37 × 107. Ultrathin 2D Bi2Se3 nanosheets have fast rise and fall times, ranging from 0.01 to 0.12 and 0.01 to 0.06 s, respectively, at different wavelengths. Ultrathin Bi2Se3 nanosheets have improved photodetection parameters as compared to multilayered nanosheets due to the high surface to volume ratio, reduced recombination and trapping of charge carrier, improved carrier confinement, and faster carrier transport due to the thin layer.

Ultra small gold nanoclusters supported on two-dimensional bismuth selenium nanosheets for synergistic photothermal and photodynamic tumor therapy.

Two-dimensional (2D) bismuth selenium (Bi2Se3) nanosheets have exceptional surface area and superior surface modification capabilities, facilitating the effective loading of nanoprobes, metal particles, and other substances. Additionally, thiolated ultrasmall gold nanoclusters (Au NCs), distinguished by their high photoluminescent activity and modulatable surface charges, enable efficient loading onto the 2D Bi2Se3 surfaces. In this study, we successfully prepared Bi2Se3 nanosheets by sonication-assisted liquid phase exfoliation and loaded Au clusters on their surface through an amide bond reaction. The loading of Au NCs significantly augments the photothermal and photocatalytic capabilities of Bi2Se3 nanosheets and exhibits obvious anti-cancer therapeutic effects through in vitro and in vivo experiments. In summary, the as-prepared AuNC@Bi2Se3 nanocomposites showed combined near-infrared light-initiated photothermal/photodynamic therapy (PTT/PDT) against tumors, demonstrating their potential as novel theranostic agents for biomedical applications.

Exploring charge transfer mechanisms and optical properties in vdW heterostructures of MoS2 and Bi2Se3 at nanoscale regime

We report here the two-dimensional layered material of MoS2/Bi2Se3 vdW heterostructures formed by ultrasonication of different concentrations of exfoliated MoS2 and Bi2Se3 nanosheets. The vdW heterostructures show unique optical characteristics compared to individual exfoliated nanosheets. The enhanced lifetime of heterostructures explained the charge transfer with increasing efficacy for producing optoelectronic devices. Raman spectroscopy confirms the presence of intrinsic Raman active modes of Bi2Se3, MoS2, and respective modes of vdW heterostructures. TEM images show characteristic lattice planes in both materials and clear overlapping regimes, confirming successful heterojunction formation. Further, Zeta potential confirms the enhanced stability of the heterostructures formed while the significant PL quenching, strongly suggests the presence of charge transfer processes within the heterostructures. Ultrafast pump-probe spectroscopy further confirms the non-linear charge transfer and relaxation mechanism of the heterostructures. We employed Surface Xplorer and Glotaran software for model fitting and Glotaran's global fitting revealed unresolved charge carrier dynamics.

Bismuth dichalcogenide-exfoliated Bi2Se3 nanosheets: A novel approach for hexavalent chromium and azo compound photocatalysis

A promising approach for the photocatalytic degradation of hexavalent chromium [Cr(VI)] and azo compounds in wastewater involves utilizing exfoliated nanosheets derived from bismuth dichalcogenide crystals, specifically Bi2Se3. In this study, we synthesized Bi2Se3 nanosheets through a straightforward sonication method using N, N-Dimethylformamide as the solvent. The resulting Bi2Se3 nanosheets displayed substantial surface areas, layered sheet structures resembling rocks, and exhibited single crystalline characteristics, featuring an optical bandgap of 5.30 eV and a lattice spacing of 0.505 nm. Photocatalytic assessments employing methyl orange (MO) and Cr(VI) as model pollutants demonstrated remarkable efficiency, achieving degradation rates of up to 81.2% within 240 min and 88.4% within 60 min, respectively, under visible light exposure. Both reactions adhered to pseudo-first-order kinetics, with kinetic constants (k) of 0.0038 min−1 for MO and 0.007 min−1 for Cr(VI). The underlying photocatalytic mechanism involved the transfer of electrons from the Bi2Se3 nanosheets to the pollutants adsorbed on their surface, resulting in the efficient detoxification of wastewater. This investigation underscores the potential of exfoliated Bi2Se3 nanosheets as exceptionally effective and environmentally sustainable photocatalysts for the remediation of wastewater contaminated with Cr(VI) and MO, making significant contributions to the field of environmental remediation. This research not only provides insights into the novel utilization of Bi2Se3 nanosheets but also addresses urgent environmental issues, indicating its potential significance in promoting sustainable wastewater treatment methods.

Composite films based on Bi2Se3 nanosheets and carbon nanotubes with photothermal and photodynamic functions for synergistic treatment

The use of functional nanomaterials to realize tumor therapeutic therapy has received considerable attention. However, a single type of nanomaterial usually can only achieve one specific function, and may cause biosafety problems due to poor metabolism. In this work, we have designed a kind of nanocomposite film based on Bi2Se3 nanosheets and carbon nanotubes, which can achieve efficient photothermal conversion and reactive oxygen species generation under near-infrared laser irradiation. Moreover, the developed films showed good biocompatibility in vivo. The multifunctional films showed remarkable therapeutic effects under 808 nm excitation with 0.3 W/cm2, which avoiding the introduction of nano-reagents into the mice and excessive laser power damage. Our work will provide reference for the use of nanomaterials with heterojunctions in synergistic therapy strategies of photothermal and photodynamic therapy.

Antioxidative 2D Bismuth Selenide via Halide Passivation for Enhanced Device Stability.

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.

An injectable hydrogel based on Bi2Se3 nanosheets and hyaluronic acid for chemo-photothermal synergistic therapy

To resolve poor accumulation caused by systemic administration, injectable and responsive hydrogels are the prospective drug delivery systems for localized tumor treatment, owning to negligible invasiveness and accurate administration. Herein, an injectable hydrogel, based on dopamine (DA) crosslinked hyaluronic acid and Bi2Se3 nanosheets (NSs) loading with doxorubicin (DOX) coated with polydopamine (Bi2Se3-DOX@PDA), was developed for synergistic chem-photothermal cancer therapy. The ultrathin functional Bi2Se3-DOX@PDA NSs could be responsive to the weak acidic condition and photothermal effect under NIR laser irradiation, achieving controlled release of DOX. Moreover, nanocomposite hydrogel based on hyaluronic acid matrix could be precisely administrated through intratumoral injection since its injectability and self-healing capacity, remaining at injected sites for at least 12 days. Furthermore, the excellent therapeutics effect of Bi2Se3-DOX@PDA nanocomposite hydrogel was demonstrated on 4 T1 xenograft tumor with outstanding injectability and negligible systemic side-effect. In short, the construction of Bi2Se3-DOX@PDA nanocomposite hydrogel paves a prospective path for local treatment of cancers.

Topological insulator Bi2Se3 for highly sensitive, selective and anti-humidity gas sensors

Chemiresistive gas sensors generally surfer from low selectivity, inferior anti-humidity, low response signal or signal-to-noise ratio, severely limiting the precise detection of chemical agents. Herein, we exploit high-performance gas sensors based on topological insulator Bi2Se3 that is distinguished from conventional materials by robust metallic surface states protected by time-reversal symmetry. In the presence of Se vacancies, Bi2Se3 nanosheets exhibit excellent gas sensing capability toward NO2, with a high response of 93% for 50ppm and an ultralow theoretical limit of detection concentration about 0.06ppb at room temperature. Remarkably, Bi2Se3 demonstrates ultrahigh anti-humidity interference characteristics, as the response with standard deviation of only 3.63% can be achieved in relative humidity range of 0-80%. These findings are supported by first-principles calculations, with analyses on adsorption energy and charge transfer directly revealing the anti-humidity and selectivity. This work may pave the way for implementation of exotic quantum states for intelligent applications.

Bi2Se3 nanosheets-based photothermal composites with hydrophobic surface for synergistic anti-/de-icing

Ice accumulation-induced damage to outdoor equipment such as wind turbine blades, aircraft and weaponry has been a long-standing concern. The traditional two-dimensional (2D) photothermal nanomaterials, which are extensively applied for de-icing, have strong phonon diffusion and high thermal conductivity, causing great heat loss and limit the application in the field of heat retention. Herein, Bi2Se3 nanosheets with photothermal effect are selected in terms of solar harvesting and heat loss reduction, endowing the composite membrane with outstanding light absorption (over 90%) and low thermal conductivity (0.054 W (mK)−1). The real-time conversion of solar-heat-electricity is further recorded, demonstrating an electrical output power density of about 110.5 μW cm−2. Furthermore, rose petals-like surface is fabricated by using fabric as a template in a scalable way and the slippery coating is prepared via in-situ growth of octadecyltrichlorosilane. Such structural design enables membrane desired hydrophobicity (contact angle 137°), which lead to the shedding of water and melted ice. This kind of anti and de-icing device can provide a valuable guidance for the design of sustainable and intelligent device in the future.

A heterojunction composite of Bi2Se3 nanosheets and MoO3 nanobelts for a high-performance triethylamine sensor

A triethylamine (TEA) sensor based on Bi2Se3 nanosheets and MoO3 nanobelts with high response was designed using hydrothermal and ultra-sonication strategies.

N-type flexible Bi2Se3 nanosheets/SWCNTs composite films with improved thermoelectric performance for low-grade waste-heat harvesting

Due to the limited thermoelectric performance of polymers and intrinsic rigidness of inorganic materials, it is difficult to obtain n-type thermoelectric materials and devices with low-cost, excellent flexibility, and high performance. In this work, we have successfully synthesized n-type flexible free-standing thermoelectric films by a low-cost solvothermal method, which is composed of Bi2Se3 nanosheets and single-wall carbon nanotubes (SWCNTs). Bi2Se3 nanosheets with excellent crystallinity and rhombohedral morphology were grown on SWCNTs. The optimized Bi2Se3/SWCNTs composite films exhibited a high electrical conductivity of 292.7 S cm−1 and a Seebeck coefficient of − 42.4 μV K−1 at room temperature, eventually achieving an improved power factor of 52.7 μW m−1 K−2. Furthermore, the composite films exhibited excellent flexibility due to the interweaving of Bi2Se3 nanosheets with SWCNTs, where the thermoelectric performance remained almost unchanged after 5000 bending cycles around a 3.5 mm radius rod. A thermoelectric device, composed of the optimized films, was constructed to further show the practicality, which generated a voltage and a power density of 11.5 mV and 86.2 μW cm−2 at a temperature gradient of 58 K, respectively. This work can provide support for the preparation of other n-type free-standing thermoelectric films with both high thermoelectric performance and excellent flexibility.

Mode-Locked YDFL Using Topological Insulator Bismuth Selenide Nanosheets as the Saturable Absorber

Fiber lasers have long remained relevant for various applications worldwide in many industries. This paper presents a mode-locked ytterbium-doped fiber laser (YDFL) using our home-made topological insulator Bi2Se3 nanosheets (TI Bi2Se3) as the saturable absorber. The fabricated TI Bi2Se3 is transported to the end of the fiber ferrule using an optical deposition process, which is a key ingredient for initiating a pulsed fiber laser. With a pump power of 211.1 mW, the captured repetition rate and pulse width are 8.3 MHz and 6.2 ns, respectively. The length of the setup configuration is approximately 20 m, which corresponds to an output power measurement of 12.4 mW with a calculated pulse energy of 1.5 nJ. There are no significant Kelly sidebands, but the strong stability of the pulsed laser is defined by a high signal-to-noise ratio (SNR) of around 60.35 dB.