Synthesis of pomegranate-like Bi2Se3@C composite for high volume specific capacity lithium storage

Rational Design of 2D/3D Bi2O2Se-CNT Hybrid Architectures for Synergistic Lithium Storage

The development of advanced anode materials with high capacity and structural stability addressing the limitations of conventional graphite anodes in theoretical capacity (372 mA h g-1) and severe volume expansion remains a critical challenge for lithium-ion batteries (LIBs). Herein, we propose a structural engineering strategy through high-temperature calcination to construct 2D layered Bi2O2Se integrated with optimized 3D carbon nanotube (CNT) frameworks (Bi2O2Se-CNT-x). Comprehensive characterization (XRD, Raman, FESEM, XPS) verifies the high crystallinity of Bi2O2Se and the successful establishment of 3D conductive networks through interfacial coupling with CNTs. Electrochemical evaluation demonstrates that the optimized Bi2O2Se-CNT-2 composite delivers a remarkable initial discharge capacity of 1544.7 mA h g-1 at 0.1 A g-1, significantly outperforming pristine Bi2O2Se (124.3 mA h g-1). Notably, it maintains superior rate capability (405.0 mA h g-1 at 2 A g-1, 35.2% capacity retention) and cycling stability (74.8% capacity retention after 250 cycles), attributed to the synergistic effects between 2D Bi2O2Se lamellae and the conductive CNT matrix. The 3D CNT network facilitates rapid electron transport while mitigating volume fluctuations, whereas the layered Bi2O2Se enables a hybrid storage mechanism combining intercalation, conversion, and alloying reactions. This work broadens the application horizons of 2D layered materials in energy storage systems.

Exploring the electrochemical performance of layered Bi2Se3 hexagonal platelets as the anode material for lithium-ion batteries

The escalating need for lithium-ion batteries (LIBs), driven by their expanding range of applications in our daily lives, has led to a surge in interest in metal selenides as potential anode materials. Among them, Bi2Se3 stands out as a promising anode material for LIBs due to its unique layered structure. Herein, we explored hexagonally structured layered Bi2Se3 platelets synthesized using the solvothermal method. The electrochemical performance of these platelets in LIBs was thoroughly examined, revealing an impressive initial discharge specific capacity of 556 mA h g-1 at a current density of 100 mA g-1 and a coulombic efficiency of 66.5%. Improved cycling stability, rate performance, and discharge voltage profile at various current densities were observed. The plateaus observed during the charge/discharge profile were clearly illustrated by the CV results. The reaction kinetics indicated that both ion diffusion and pseudo-capacitance behavior are crucial for the observed high electrochemical performance. Moreover, the hexagonal Bi2Se3 platelets exhibited a high ion-diffusion coefficient of 1.8 × 10-13 cm2 s-1 and a charge transfer impedance of 23 Ω post-cycling. Furthermore, the crystal structure, lattice vibrational bonding, and surface morphology of Bi2Se3 were explored using X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. FTIR spectroscopy was utilized for identifying the functional groups, while X-ray photoelectron spectroscopy (XPS) was used to identify the elemental composition and oxidation states of Bi2Se3.

Heterogeneous Interface Design with Oxygen Vacancy-Rich Assistance High-Capacity Titanium-Based Oxide Anode Materials for Sodium-Ion Batteries

Researchers are paying more attention to sodium-ion batteries (SIBs) because of their abundant supply of sodium resources and affordable price. TiO2 offers excellent safety and a long lifespan as an anode material for SIBs. However, the process kinetics is slow due to its limited Na+ storage efficiency, weak conductivity, and irreversible Na+ capture. In order to address these issues, this review uses a mix of the template approach and the double-hydrolysis method to manage the structure and diffusion of TiO2-based anode materials by synthesizing FeTiO3/TiO2 heterostructured double-shell microspheres (FTO). Through the built-in electric field effect caused by their heterostructures, FTO materials improve reaction kinetics, boost electronic conductivity, and lower the diffusion energy barrier of Na+. Their distinctive double-shell structure can increase electrolyte infiltration, shorten the diffusion distance between ions and electrons, and accommodate volume expansion during cycling. Furthermore, the irreversible capture of Na+ and the unfavorable interactions between the surface active site and electrolyte can be successfully inhibited by FTO heterostructures. FTO has an exceptionally high capacity (reaching 362.7 mA h g-1 after 60 cycles at 20 mA g-1) and excellent cycle stability (with a decay rate of 0.0061% after 1000 cycles at 2 A g-1). The strategy of constructing heterogeneous interfaces assists with high-performance SIB anode design.

Vacancy-Defect Ternary Topological Insulators Bi2Se2Te Encapsulated in Mesoporous Carbon Spheres for High Performance Sodium Ion Batteries and Hybrid Capacitors

Ternary topological insulators have attracted worldwide attention because of their broad application prospects in fields such as magnetism, optics, electronics, and quantum computing. However, their potential and electrochemical mechanisms in sodium ion batteries (SIBs) and hybrid capacitors (SIHCs) have not been fully studied. Herein, a composite material comprising vacancy-defects ternary topological insulator Bi2Se2Te encapsulated in mesoporous carbon spheres (Bi2Se2Te@C) is designed. Bi2Se2Te with ample vacancy-defects has a wide interlayer spacing to enable frequent insertion/extraction of Na+ and boost reaction kinetics within the electrode. Meanwhile, the Bi2Se2Te@C with optimized yolk-shell structure can buffer the volume variation without breaking the outer protective carbon shell, ensuring structural stability and integrity. As expected, the Bi2Se2Te@C electrode delivers high reversible capacity and excellent rate capability in half SIB cells. Various electrochemical analyses and theoretical calculations manifest that Bi2Se2Te@C anode confirms the synergistic effect of ternary chalcogenide systems and suitable void space yolk-shell structure. Consequently, the full cells of SIB and SIHC coupled with Bi2Se2Te@C anode exhibit good performance and high energy/power density, indicating its widespread practical applications. This design is expected to offer a reliable strategy for further exploring advanced topological insulators in Na+-based storage systems.

Synergistic activation of lamellar bismuth selenide anchored functionalized carbon nanofiber for detecting hazardous carbendazim in environmental water samples

Pesticides pollute natural water reservoirs through persistent accumulation. Therefore, their toxicity and degradability are serious issues. Carbendazim (CBZ) is a pesticide used against fungal infections in agricultural crops, and its overexploitation detrimentally affects aquatic ecosystems and organisms. It is necessary to design a logical, efficient, and field-deployable method for monitoring the amount of CBZ in environmental samples. Herein, a nano-engineered bismuth selenide (Bi2Se3)/functionalized carbon nanofiber (f-CNF) nanocomposite was utilized as an electrocatalyst to fabricate an electrochemical sensing platform for CBZ. Bi2Se3/f-CNF exhibited a substantial electroactive surface area, high electrocatalytic activity, and high conductivity owing to the synergistic interaction of Bi2Se3 with f-CNF. The structural chemical compositions and morphology of the Bi2Se3/f-CNF nanocomposite were confirmed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and field-emission scanning electron microscopy (FESEM). Electrochemical analysis was carried out using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). The voltammetry and impedance experiments exposed that the Bi2Se3/f-CNF-modified GCE has attained adequate electrocatalytic function with amended features of electron transportation (Rct = 35.93 Ω) and improved reaction sites (0.082 cm2) accessible by CBZ moiety along with exemplary electrochemical stability (98.92%). The Bi2Se3/f-CNF nanocomposite exhibited higher sensitivity of 0.2974 μA μM-1cm-2 and a remarkably low limit of detection (LOD) of 1.04 nM at a broad linera range 0.001-100 μM. The practicability of the nanocomposite was tested in environmental (tap and pond water) samples, which supports excellent signal amplification with satisfactory recoveries. Hence, the Bi2Se3/f-CNF nanocomposite is a promising electrode modifier for detecting CBZ.

Nanoconfinement of ultra-small Bi2Te3 nanocrystals on reduced graphene oxide: a pathway to high-performance sodium-ion battery anodes

Bismuth telluride (Bi2Te3) nanomaterials have attracted considerable attention owing to their intriguing physicochemical properties and wide-ranging potential applications arising from their distinctive layered structure and nanoscale size effects. However, synthesizing sub-100 nm ultra-small Bi2Te3 nanocrystals remains a formidable challenge. To date, there has been little investigation on the performance of these ultra-small Bi2Te3 nanocrystals in sodium-ion batteries (SIBs). This study presents a general strategy for synthesizing ultra-small Bi2Te3 nanocrystals on reduced graphene oxide (Bi2Te3/rGO) through a nanoconfinement approach. First-principles calculations and electrochemical kinetic studies confirm that the ultra-small Bi2Te3/rGO composite material can effectively mitigate volumetric expansion, preserve electrode integrity, and enhance electron transfer, Na-ion adsorption, and diffusion capacity. As a result, the Bi2Te3/rGO electrode demonstrates a remarkable initial specific capacity of 521 mA h g-1 at 0.1 A g-1, showcasing outstanding rate behaviour and long-lasting cycle life exceeding 800 cycles at 1 A g-1 while preserving exceptional rate properties. The function of the battery is indicated by ex situ TEM and XPS findings, which propose a conventional dual mechanism involving conversion and alloying. This work paves the way for rapid advancements in Bi2Te3-based SIB anodes while contributing to our understanding of sodium ion storage mechanisms.

3D hierarchical self-supporting Bi2Se3-based anode for high-performance lithium/sodium-ion batteries

Bi2Se3 is a promising material for anodes in lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) due to its abundance, easy preparation, and high capacity. However, its practical application is hindered by low conductivity and significant volume variation during cycling, leading to poor rate capability and cycling stability. Herein, a novel composite consisting of Bi2Se3 nanoplates deposited on carbon cloth (CC) and encapsulated by reduced graphene oxide (rGO) has been designed and synthesized. The composite structure combines the advantages of the Bi2Se3 nanoplates, CC substrate, and rGO encapsulation, leading to enhanced electrochemical properties. The physical vapor deposition of Bi2Se3 nanoplates onto CC ensures a high loading of active material, while the rGO encapsulation provides a conductive and stable framework for the composite. This synergistic design allows for improved electron and ion transport, as well as efficient accommodation of the volume changes during cycling. In LIBs, the composite demonstrates a high reversible capacity of 467.5 mAh/g at 0.1 A/g after 120 cycles. Moreover, it displays an outstanding rate capability, delivering a capacity of 398.6 mAh/g at 5.0 A/g. Similarly, in SIBs, the composite maintains a reversible capacity of 375.3 mAh/g at 0.1 A/g over 100 cycles and exhibits a high-rate capacity of 286.3 mAh/g at 5.0 A/g. This work represents a significant step forward in addressing the challenges associated with Bi2Se3 as an anode material, paving the way for the development of high-performance LIBs and SIBs.

Pseudopyrolysis of Metal-Organic Frameworks: A Synchronous Nucleation Mechanism to Synthesize Ultrafine Metal Compound Nanoparticles

Metal-Organic frameworks (MOFs) are increasingly being investigated for the synthesis of carbon-supported metal-based ultrafine nanoparticles (UNPs). However, the collapse of the carbon framework and aggregation of metal particles in the pyrolysis process have severely hindered their stability and applications. Here, we report the synchronous nucleation pseudopyrolysis of MOFs to confine Fe/FeO_x UNPs in intact porous carbon nanorods (IPCNs), revealed by in situ transmission electron microscopy experiments and ex situ structure analysis. The pseudopyrolysis mechanism enables strong physical and chemical confinement effects between UNPs and carbon by moderate thermal kinetics and abundant oxygen defects. Further, this strong confinement is greatly beneficial for subsequent chemical transformations to obtain different Fe-based UNPs and excellent electrochemical performance. As a proof of concept, the as-prepared FeSe UNPs in IPCNs show superior lithium storage performance with an ultrahigh and stable capacity of 815.1 mAh g^-1 at 0.1 A g ^-1 and 379.7 mAh g^-1 at 5 A g^-1 for 1000 cycles.