The use of organic–inorganic nanocomposites has shown the greatest potential for engineering efficient flexible thermoelectric devices. In this work, a novel approach of encapsulation of as‐grown ...bismuth selenide‐multiwalled carbon nanotubes (Bi2Se3‐MWCNT) hybrid network in polyvinyl alcohol for fabrication of n‐type flexible thermoelectric films is demonstrated as a successful alternative to the mechanically mixed counterparts. The developed stable flexible n‐type thermoelectric material has a Seebeck coefficient and power factor at room temperature as high as −85 μV K−1 and 0.4 μW m−1 K−2, and figure‐of‐merit, exceeding the value shown by the mixed counterpart by ≈2 orders of magnitude, while requiring 3–4 times less inorganic material in comparison with mixed composites. Charge carrier transport mechanisms and contribution of Bi2Se3 and MWCNT components of not encapsulated and encapsulated hybrid networks to the total Seebeck coefficient, electrical conductance, and power factor are studied. In addition, the fabricated flexible thermoelectric films show good environmental stability at relative humidity levels up to 60%, as well as great mechanical and electrical stability with the increase of resistance within 0.5% and deviations of the Seebeck coefficient within 2% from the initial value during the 100 repetitive bending cycles.
A novel technique for fabrication of flexible n‐type thermoelectric nanocomposites by encapsulating as‐grown Bi2Se3‐ multiwalled carbon nanotube hybrid networks in nonconductive poly(vinyl alcohol) without disruption of the interconnects formed in the hybrid network during its growth is demonstrated. This innovative and simple method results in obtaining flexible and highly durable thermoelectric films with two times higher figure of merit in comparison with the state‐of‐the‐art counterparts.
Two-dimensional (2D) heterostructures are more than a sum of the parent 2D materials, but are also a product of the interlayer coupling, which can induce new properties. In this paper, we present a ...method to tune the interlayer coupling in Bi
Se
/MoS
2D heterostructures by regulating the oxygen presence in the atmosphere, while applying laser or thermal energy. Our data suggest that the interlayer coupling is tuned through the diffusive intercalation and deintercalation of oxygen molecules. When one layer of Bi
Se
is grown on monolayer MoS
, an influential interlayer coupling is formed, which quenches the signature photoluminescence (PL) peaks. However, thermally treating in the presence of oxygen disrupts the interlayer coupling, facilitating the emergence of the MoS
PL peak. Our density functional theory calculations predict that intercalated oxygen increases the interlayer separation ∼17%, disrupting the interlayer coupling and inducing the layers to behave more electronically independent. The interlayer coupling can then be restored by thermally treating in N
or Ar, where the peaks will requench. Hence, this is an interesting oxygen-induced switching between "non-radiative" and "radiative" exciton recombination. This switching can also be accomplished locally, controllably, and reversibly using a low-power focused laser, while changing the environment from pure N
to air. This allows for the interlayer coupling to be precisely manipulated with submicron spatial resolution, facilitating site-programmable 2D light-emitting pixels whose emission intensity could be precisely varied by a factor exceeding 200×. Our results show that these atomically thin 2D heterostructures may be excellent candidates for oxygen sensing.
The challenge with aqueous zinc‐ion batteries (ZIBs) lies in finding suitable cathode materials that can provide high capacity and fast kinetics. Herein, two‐dimensional topological Bi2Se3 with ...acceptable Bi‐vacancies for ZIBs cathode (Cu‐Bi2−xSe3) is constructed through one‐step hydrothermal process accompanied by Cu heteroatom introduction. The cation‐deficient Cu‐Bi2−xSe3 nanosheets (≈4 nm) bring improved conductivity from large surface topological metal states contribution and enhanced bulk conductivity. Besides, the increased adsorption energy and reduced Zn2+ migration barrier demonstrated by density‐functional theory (DFT) calculations illustrate the decreased Coulombic ion‐lattice repulsion of Cu‐Bi2−xSe3. Therefore, Cu‐Bi2−xSe3 exhibits both enhanced ion and electron transport capability, leading to more carrier reversible insertion proved by in situ synchrotron X‐ray diffraction (SXRD). These features endow Cu‐Bi2−xSe3 with sufficient specific capacity (320 mA h g−1 at 0.1 A g−1), high‐rate performance (97 mA h g−1 at 10 A g−1), and reliable cycling stability (70 mA h g−1 at 10 A g−1 after 4000 cycles). Furthermore, quasi‐solid‐state fiber‐shaped ZIBs employing the Cu‐Bi2−xSe3 cathode demonstrate respectable performance and superior flexibility even under high mass loading. This work implements a conceptually innovative strategy represented by cation defect design in topological insulator cathode for achieving high‐performance battery electrochemistry.
The challenge with aqueous zinc‐ion batteries (ZIBs) lies in the design of suitable cathode materials. Herein, two‐dimensional topological Bi2Se3 with acceptable cation vacancies for ZIBs cathode is constructed through one‐step hydrothermal process, which exhibits both enhanced ion and electron transport capability. The remarkable reversible charge storage capacity points to its promising strategy for achieving high performance aqueous zinc‐ion batteries.
This paper presents a study on the lattice dynamics of doped topological insulator (Cu,Ni)xBi2Se3 single crystals probed using Raman scattering spectroscopy. The single crystals were grown by melting ...and characterized through X-ray diffraction and scanning electron microscopy with energy dispersive X-ray spectroscopy. The diffraction patterns were indexed within the space group R-3m and the samples belonged to the rhombohedral layered structure group typical of Bi2Se3. A Raman scattering study was developed, in which three modes were observed at low frequencies: A1g1, Eg2 and A1g2. The low frequency Eg1 mode, even if theoretically predicted, was not observed. No difference was observed in Raman lines between the pure and (Cu,Ni)-doped samples, indicating that the Cu and Ni are probably intercalated (and not substituted) between the Se layers.
•The samples are highly oriented with approximately 100 nm tick lamellas.•No difference was observed in Raman modes between pure and (Cu,Ni)-doped samples.•Cu and Ni were intercalated (and not substituted) between the Se layers.
•High-performance layered Bi2Se0.5Te2.5 thin films fabricated.•Structure-induced defects regulate high power factor.•Enhanced thermal stability achieved through structural tuning of thin ...films.•nReduced variation between highest and lowest seebeck coefficients.•Increased high-temperature power factor to 28 × 10−4 W m−1K−2.
Bi2Te3-based n-type thin films with high thermoelectric performances are typically synthesised through the formation of dense structures, a process conventionally conducted at high temperatures. However, this method compromises thermal stability. In this study, structural design and multiple-step annealing were employed to enhance the thermal stability of high-performance Bi2Se0.5Te2.5 thin films. Post-annealing, the disparity in the values of the Seebeck coefficient over the entire test temperature range, was reduced to 20 μV K−1, which is approximately 32 % compared to pre-annealing measurements. The layered Bi2Se0.5Te2.5 thin film demonstrated an elevated power factor (28 × 10−4 W m−1K−2), which was maintained across a broad temperature spectrum. This multiple-step annealing approach not only refines the structural integrity by extending the atomic diffusion duration but also mitigates defects and augments compositional uniformity at reduced temperatures. Consequently, layered Bi2Se0.5Te2.5 films emerge as promising candidates for thermoelectric materials, offering enhanced long-term stability for diverse applications, including electric and hybrid electric vehicles, and portable electronic devices.
Sub-3 nm ultrasmall Bi2Se3 nanodots stabilized with bovine serum albumin were successfully synthesized through a reaction of hydroxyethylthioselenide with bismuth chloride in aqueous solution under ...ambient conditions. These nanodots exhibit a high photothermal conversion efficiency (η = 50.7%) due to their strong broad absorbance in the near-infrared (NIR) window and serve as a nanotheranostic agent for photoacoustic imaging and photothermal cancer therapy. In addition, they also display radioenhancement with a ratio of 6% due to their sensitivity to X-rays, which makes them a potential sensitizer for radiotherapy. These nanodots were also labled with radioactive 99mTc for quantification of their biodistribution by single-photon-emission computed tomography (SPECT)/computed tomography (CT) imaging. Our work demonstrates the potential of ultrasmall Bi2Se3 nanodots in multimodal imaging-guided synergetic radiophotothermal therapy of cancer.
Elaborately designed biocompatible nanoplatforms simultaneously having diverse therapeutic and imaging functions are highly desired for biomedical applications. Herein, a Bi2Se3 nanoagent with a ...special morphology as a nanoscale spherical sponge (NSS) has been fabricated and investigated in vitro and in vivo. The highly porous NSS exhibits strong, steady, and broad-band absorbance in the near-infrared range as well as high efficiency and stability of photothermal conversion, resulting in high antitumor efficacy for photothermal therapy (PTT). Together with a high X-ray attenuation coefficient (218% that of the clinically used iopromide), the NSS shows excellent performance on triple-modal high-contrast imaging, including X-ray-computed tomography, multispectral optoacoustic tomography, and infrared thermal imaging. Furthermore, the high surface area and porous structure impart the NSS a competent drug loading capability as high as 600% of that on Bi2Se3 nanoplates, showing a bimodal pH/photothermal sensitive drug release and pronounced synergetic effects of thermo-chemotherapy with a tumor inhibition ratio even higher than that of PTT alone (∼94.4% vs ∼66.0%). Meanwhile, the NSS is highly biocompatible with rather low in vitro/in vivo toxicity and high stability, at variance with easily oxidized Bi2Se3 nanoagents reported previously. Such biocompatible single-component theranostic nanoagents produced by a facile synthesis and highly integrated multimodal imaging and multiple therapeutic functions may have substantial potentials for clinical antitumor applications. This highly porous nanostructure with a large fraction of void space may allow versatile use of the NSS, for example, in catalysis, gas sensing, and energy storage, in addition to accommodating drugs and other biomolecules.
The shuttling behavior and sluggish conversion kinetics of intermediate lithium polysulfides (LiPS) represent the main obstacles to the practical application of lithium–sulfur batteries (LSBs). ...Herein, an innovative sulfur host is proposed, based on an iodine‐doped bismuth selenide (I‐Bi2Se3), able to solve these limitations by immobilizing the LiPS and catalytically activating the redox conversion at the cathode. The synthesis of I‐Bi2Se3 nanosheets is detailed here and their morphology, crystal structure, and composition are thoroughly. Density‐functional theory and experimental tools are used to demonstrate that I‐Bi2Se3 nanosheets are characterized by a proper composition and micro‐ and nano‐structure to facilitate Li+ diffusion and fast electron transportation, and to provide numerous surface sites with strong LiPS adsorbability and extraordinary catalytic activity. Overall, I‐Bi2Se3/S electrodes exhibit outstanding initial capacities up to 1500 mAh g−1 at 0.1 C and cycling stability over 1000 cycles, with an average capacity decay rate of only 0.012% per cycle at 1 C. Besides, at a sulfur loading of 5.2 mg cm−2, a high areal capacity of 5.70 mAh cm−2 at 0.1 C is obtained with an electrolyte/sulfur ratio of 12 µL mg−1. This work demonstrated that doping is an effective way to optimize the metal selenide catalysts in LSBs.
An innovative sulfur host, based on an iodine doped bismuth selenide (I‐Bi2Se3), is demonstrated as a multifunctional polysulfide mediator by immobilizing the LiPS and catalytically activating the redox conversion. The promoted adsorption capacity and catalytic effect are confirmed by experiments and theoretical calculations; thus, batteries with exceptional lifespan are delivered.
PDF
