Constructing hierarchical MoS2/WS2 heterostructures in dual carbon layer for enhanced sodium ions batteries performance.

The escalating global demand for clean energy has spurred substantial interest in sodium-ion batteries (SIBs) as a promising solution for large-scale energy storage systems. However, the insufficient reaction kinetics and considerable volume changes inherent to anode materials present significant hurdles to enhancing the electrochemical performance of SIBs. In this study, hierarchical MoS2/WS2 heterostructures were constructed into dual carbon layers (HC@MoS2/WS2@NC) and assessed their suitability as anodes for SIBs. The internal hard carbon core (HC) and outer nitrogen-doped carbon shell (NC) effectively anchor MoS2/WS2, thereby significantly improving its structural stability. Moreover, the conductive carbon components expedite electron transport during charge-discharge processes. Critically, the intelligently engineered interface between MoS2 and WS2 modulates the interfacial energy barrier and electric field distribution, promoting faster ion transport rates. Capitalizing on these advantageous features, the HC@MoS2/WS2@NC nanocomposite exhibits outstanding electrochemical performance when utilized as an anode in SIBs. Specifically, it delivers a high capacity of 415 mAh/g at a current density of 0.2 A/g after 100 cycles. At a larger current density of 2 A/g, it maintains a commendable capacity of 333 mAh/g even after 1000 cycles. Additionally, when integrated into a full battery configuration with a Na3V2(PO4)3 cathode, the Na3V2(PO4)3//HC@MoS2/WS2@NC full cell delivers a high capacity of 120 mAh/g after 300 cycles at 1 A/g. This work emphasizes the substantial improvement in battery performance that can be attained through the implementation of dual carbon confinement, offering a constructive approach to guide the design and development of next-generation anode materials for SIBs.

Novel Electrospun Sn-Based Composite Cathodes Exhibiting Extended Cycle Life for Hybrid Magnesium-Lithium Batteries.

In this study, we present a strategic approach for the structural design and composite modification of one-dimensional Sn-based nanocomposites to enhance the overall electrochemical performance of hybrid magnesium-lithium batteries (MLIBs), which are emerging as promising successors to lithium-ion batteries. By using electrospinning technology, we successfully synthesized NST-SnO2, NST-SnO2-NiO, Sn-CNF, and Ni3Sn2-CNF composite cathodes, as well as analyzed the synthesis mechanism of the four Sn-based cathodes. The 100-cycle testing at a current density of 500 mA·g-1 revealed that NST-SnO2 maintained a discharge specific capacity of 129.8 mA h·g-1 with a retention rate of 90.76%, while NST-SnO2-NiO achieved a higher capacity of 147.4 mA h·g-1 and an 88.05% retention rate. Notably, Sn-CNF and Ni3Sn2-CNF exhibited initial discharge capacities of 66.7 and 79.6 mA h·g-1, respectively, coupled with exceptional cycle stability, evidenced by retention rates of 104.19 and 102.38%. The remarkable cycling stability observed in these novel cathodes is attributed to their robust structural integrity, thus demonstrating the potential for an extended cycle life in MLIBs. This work provides significant advancement in the development of high-performance electrode materials for next-generation hybrid magnesium-lithium energy storage systems.

Remarkable purification of organic dyes by NiOOH-modified industrial waste residues.

Extracting functional materials from industrial waste residues to absorb organic dyes can maximize waste reuse and minimize water pollution. However, the extraordinarily low purification efficiency still limits the practical application of this strategy. Herein, the lamellar NiOOH is in-situ anchored on the industrial waste red mud surface (ARM/NiOOH) as an adsorbent to purify organic dyes in wastewater. ARM/NiOOH adsorbent with high specific surface area and porosity provides considerable active sites for the congo red (CR), thereby significantly enhancing the removal efficiency of CR. Besides, we fit a reasonable adsorption model for ARM/NiOOH adsorbent and investigate its adsorption kinetics. Resultantly, ARM/NiOOH adsorbent can remarkably adsorb 348.0 mg g-1 CR within 5 min, which is 7.91 times that of raw RM. Our work provides a strategy for reusing industrial waste and purifying sewage pollution, which advances wastewater treatment engineering.

Flexible, recoverable, and efficient photocatalysts: MoS2/TiO2 heterojunctions grown on amorphous carbon-coated carbon textiles.

Most traditional powder photocatalysts are not easily recovered. Herein, we report a flexible and recoverable photocatalyst with superior photocatalytic activity, in which MoS2/TiO2 heterojunctions are grown on amorphous carbon-coated carbon textiles (CT@C-MoS2/TiO2). Recoverable CT@C-MoS2/TiO2 textile was used to degrade 10 mg L-1 rhodamine B, leading to a degradation rate of up to 98.8 % within 30 min. Such a degradation rate is much higher than that of most of the reported studies. A density functional theory (DFT) calculation results illustrate charge transfer mechanism inside TiO2-C, MoS2-C, and MoS2/TiO2 heterojunctions, which shows that CT@C-MoS2/TiO2 textile with three electron separation channels has a high photogenerated carrier separation rate, which remarkably enhances the photocatalytic activity. Our work provides a novel strategy to design an efficient and recoverable photocatalyst with high activity.

A strategy-purifying wastewater with waste materials: Zn2+ modified waste red mud as recoverable adsorbents with an enhanced removal capacity of congo red.

The strategy, called purifying wastewater with waste materials (PWWM), can simultaneously improve the secondary utilization of industrial waste materials and in turn, reduce environmental pollution. However, the PWWM strategy has still not been extensively used because of its low purification efficiency of organic pollutants and extremely difficult secondary utilization process. Herein, we use zinc aluminum silicate (ZAS) to modify waste granular red mud (GRM) to form a recoverable adsorbent, called ZAS/GRM adsorbent. The ZAS has been found to exhibit exceptional adsorption performance with the ability to firmly anchor onto the surface of GRM, in which heavy metal ions can effectively solidify and reduce their outflow. Furthermore, many voids have been tactfully designed in the ZAS/GRM adsorbents by using a water vapor project, which provide more active sites for congo red (CR) organic dye, thereby remarkably improving the removal efficiency of CR. From our purification of CR, we find that the CR adsorption capacity of the ZAS/GRM adsorbent is 3.509 mg g-1, which is four times higher than pure GRM (0.820 mg g-1). This study demonstrates our PWWM strategy is highly effective and can inspire more research on waste reuse.

Bimetallic MnMoO4 nanostructures on carbon fibers as flexible cathode for high performance zinc-ion batteries.

Aqueous zinc ion batteries (ZIBs) are promising energy storage devices due to the advantageous features of Zn. However, developing suitable cathode materials with high performance is still an urgent task for the development of ZIBs. In this work, we report on the preparation of a flexible cathode for ZIBs consisting of carbon fiber supported MnMoO4 nanostructures protected with N-doped carbon coatings (CF/MnMoO4@NCs). The N-doped carbon coating on MnMoO4 nanostructures can buffer volume expansion of MnMoO4, and the CF and NCs with good electronic conductivity can facilitate quick electrons transportation in the CF/MnMoO4@NCs system. The optimized CF/MnMoO4@NCs cathode exhibits high capacity and good rate capability. Specifically, it delivers an outstanding discharge capacity of 663 mA h g-1 at a current density of 0.1 A/g after 100 cycles, and at a current density of 2 A/g, the cathode can still achieve a discharge capacity of 212 mA h g-1. This work expands the choice of cathode material and provides constructive direction on designing high-performance cathode materials for ZIBs.

Heterostructured CoS2/CuCo2S4@N-doped carbon hollow sphere for potassium-ion batteries.

Potassium ions batteries (PIBs) have been regarded as a promising choice for electrical energy storage technology due to the wide distribution of potassium resources. However, developing low-cost and robust earth-rich anode materials is still a major challenge for the practical and scalable usage of PIBs. Herein, for the first time, we developed nitrogen doped carbon coating CoS2/CuCo2S4 heterostructure (CoS2/CuCo2S4@NCs) hollow spheres and evaluated as anode for PIBs. The CoS2 and CuCo2S4 heterostructure interface could generate a built-in electric field, which can fasten electrons transportation. The nanostructures could shorten the diffusion length of K+ and provide large surface area to contact with electrolytes. Furthermore, the inner hollow sphere morphology along with the carbon layer could accommodate the volume expansion during cycling. What's more, the N-doped carbon could increase the conductivity of the anodes. Benefitting from the above features, the CoS2/CuCo2S4@NCs displays an outstanding rate capability (309 mAh g-1 at 500 mA g-1 after 250 cycles) and a long-term cycling life (112 mAh g-1 at 1000 mA g-1 after 1000 cycles) in ether-based electrolyte. Conversion reaction mechanism in CoS2/CuCo2S4@NCs anode is also revealed through ex situ XRD characterizations. This work provides a practical direction for investigating metal sulfides as anode for PIBs.

Self-Standing Film Assembled using SnS-Sn/Multiwalled Carbon Nanotubes Encapsulated Carbon Fibers: A Potential Large-Scale Production Material for Ultra-stable Sodium-Ion Battery Anodes.

High-energy sodium-ion batteries have a significant prospective application as a next-generation energy storage technology. However, this technology is severely hindered by the lack of large-scale production of battery materials. Herein, a self-standing film, assembled with SnS-Sn/multiwalled carbon nanotubes encapsulated in carbon fibers (SnS-Sn/MCNTs@CFs), is prepared using ball milling and electrospinning techniques and used as sodium-ion battery anodes. To compensate the poor internal conductivity of SnS-Sn nanoparticles, MCNTs are used to interweave SnS-Sn nanoparticles to improve the conductivity. Moreover, the designed three-dimensional carbon fiber conductive network can effectively shorten the diffusion path of electron/Na+, accelerate the reaction kinetics, and provide abundant active sites for sodium absorption. Benefiting from these unique features, the self-standing film offers a high reversible capacity of 568 mA h g-1 at 0.1 A g-1 and excellent cycling stability at 1 A g-1 with a reversible capacity of 359.3 mA h g-1 after 1000 cycles. In the sodium-ion full cell device, the capacity is stable at 283.7 mA h g-1 after 100 cycles at a current of 100 mA g-1. This work provides a new strategy for electrode design and facilitates the large-scale application of the sodium-ion battery.

Bi2O3/BiVO4@graphene oxide van der Waals heterostructures with enhanced photocatalytic activity toward oxygen generation.

The van der Waals (vdW) integration enables to create heterostructures with intimate contact and bring new opportunities. However, it is not confined to layered materials but can also be generally extended to 3D materials. Multidimensional Bi2O3/BiVO4@graphene oxide (GO) van der Waals heterostructures are synthesized by one-pot wet chemistry method. Bi2O3/BiVO4 composite nanoparticles are self-assembled with GO framework by vdW interaction to form vdW heterostructures, in which GO framework allows short electron transport distance and rapid charge transfer and provides massive reactive sites. Such self-assembled heterostructures show a superior high photoactivity towards oxygen evolution with an enhanced oxygen generation rate of 1828 µmol h-1 g-1, nearly 3 times than that of pure BiVO4, attributed to the accelerated charge separation and transfer processes of Bi2O3/BiVO4@GO vdW heterostructures. This study indicates that our strategy provides a new avenue towards fabricating multi-dimensional vdW heterostructures and inspiring more innovative insights in oxygen evolution field.

High-Performance Multifunctional Carbon-Silicon Carbide Composites with Strengthened Reduced Graphene Oxide.

Materials with low density, exceptional thermal and corrosion resistance, and ultrahigh mechanical and electromagnetic interference (EMI) shielding performance are urgently demanded for aerospace and military industries. Efficient design of materials' components and microstructures is crucial yet remains highly challenging for achieving the above requirements. Herein, a strengthened reduced graphene oxide (SrGO)-reinforced multi-interfacial carbon-silicon carbide (C-SiC)n matrix (SrGO/(C-SiC)n) composite is reported, which is fabricated by depositing a carbon-strengthening layer into rGO foam followed by alternate filling of pyrocarbon (PyC) and silicon carbide (SiC) via a precursor infiltration pyrolysis (PIP) method. By increasing the number of alternate PIP sequences (n = 1, 3 and 12), the mechanical, electrical, and EMI shielding properties of SrGO/(C-SiC)n composites are significantly increased. The optimal composite exhibits excellent conductivity of 8.52 S·cm-1 and powerful average EMI shielding effectiveness (SE) of 70.2 dB over a broad bandwidth of 32 GHz, covering the entire X-, Ku-, K-, and Ka-bands. The excellent EMI SE benefits from the massive conduction loss in highly conductive SrGO skeletons and polarization relaxation of rich heterogeneous PyC/SiC interfaces. Our composite features low density down to 1.60 g·cm-3 and displays robust compressive properties (up to 163.8 MPa in strength), owing to the uniformly distributed heterogeneous interfaces capable of consuming great fracture energy upon loadings. Moreover, ultrahigh thermostructural stability (up to 2100 °C in Ar) and super corrosion resistance (no strength degradation after long-term acid and alkali immersion) are also discovered. These excellent comprehensive properties, along with ease of low-cost and scalable production, could potentially promote the practical applications of the SrGO/(C-SiC)n composite in the near future.

In situ construction of hierarchical polyaniline/SnS2@carbon nanotubes on carbon fibers for high-performance supercapacitors.

Carbon fibers (CFs) show great potential for high-performance supercapacitors in miniature electronics fields, where high energy density and long cycling life are required. However, superior combination of these two attributes in CF-based supercapacitors still presents a long-standing challenge. Herein, straight carbon nanotubes (CNTs) with radial orientation and high chemical/physical stability are served as nanoscale conductive skeletons on CFs for supporting the polyaniline (PANI)/SnS2. The SnS2 with nanoflower-like features significantly increases the specific capacitance and specific surface area (SSA); furthermore, the PANI nanolayers covered on SnS2 petals enable secondary specific capacitance enhancement and inhibition of volume expansion of SnS2 during charging/discharging processes. Benefiting from these structural merits, the resultant PANI/SnS2@CNTs/CFs hybrids exhibit high SSA (2732.5 m2 g-1), high specific capacitance (891 F g-1 at 20 mV s-1) and excellent cycling stability (83.8% after 6000 cycles at 2 A g-1). Moreover, the hybrids deliver a superior energy density of 38.7 W h kg-1 at a power density of 1 kW kg-1 and outstanding performance stability, which should prove to be vastly advantageous as compared to the reported CF-based supercapacitors. Our work puts forward a new thinking of rational construction of high-performance CF-based supercapacitors that can be used in practical energy storage devices.

Tuning wall thickness of TiO2 microtubes for an enhanced photocatalytic activity with thickness-dependent charge separation efficiency.

TiO2 microtubes with tunable wall thickness have been synthesized by a one-step electrospinning method linked with a calcination process. The wall thickness of TiO2 microtubes can be easily tuned by altering the dosage of liquid paraffin. The influence of the thickness on the light-harvesting ability and separation efficiency of the photogenerated carriers was studied using ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy, photoluminescence emission spectroscopy, and photocurrent density measurements. Results show that TiO2 microtubes with an appropriate thickness exhibit enhanced light scattering effect, UV-vis light-harvesting ability, charge separation efficiency, and photocatalytic performance. The degradation rates of rhodamine B and 2,4-dinitrophenol by using TiO2 microtubes synthesized at a dosage of 0.14 g/mL liquid paraffin are 99.9% within 60 min and 97.8% within 40 min, respectively, which are higher than most of the reported values. All these results suggest that our work provides an ideal strategy for adjusting the wall thickness of TiO2 microtubes and new approach to enhance the photocatalytic performance of TiO2.

Flexible Carbon-Fiber/Semimetal Bi Nanosheet Arrays as Separable and Recyclable Plasmonic Photocatalysts and Photoelectrocatalysts.

In this work, we prepared flexible carbon-fiber/semimetal Bi nanosheet arrays from solvothermal-synthesized carbon-fiber/Bi2O2CO3 nanosheet arrays via a reductive calcination process. The flexible carbon-fiber/semimetal Bi nanosheet arrays can function as photocatalysts and photoelectrocatalysts for 2,4-dinitorphenol oxidation. Compared with carbon-fiber/Bi2O2CO3 nanosheet arrays, the newly designed flexible carbon-fiber/semimetal Bi nanosheet arrays show enhanced ultraviolet-visible (UV-vis) light absorption efficiency and photocurrent, photocatalytic, and photoelectrocatalytic activities. Photocatalytic analyses indicate that the surface plasmon resonance (SPR) of semimetal Bi occurs under solar-simulated light irradiation during the photocatalytic process. The carbon-fiber traps the hot electrons exerted from the SPR of semimetal Bi and creates holes in the semimetal Bi nanosheets, which boosts the photocatalytic activity of the carbon fiber through plasmonic sensitization. Both photocatalytic experiments and density functional theory (DFT) calculations indicate that the electrons transferred to the carbon fiber and the holes created in semimetal Bi contribute to the formation of •O2- and •OH, respectively. The synergistic effect between electrocatalysis and photocatalysis under the solar-simulated light results in almost complete degradation of 2,4-dinitorphenol during the photoelectrocatalytic process. This work realizes a non-noble-metal plasmonic catalyst and provides a new avenue for the commercialization of photocatalysis and photoelectrocatalysis using the separable and recyclable carbon-fiber/semimetal Bi nanosheet arrays in the environment-related field.

Amorphous carbon coated SnO2 nanohseets on hard carbon hollow spheres to boost potassium storage with high surface capacitive contributions.

Potassium-ion batteries (KIBs) have becoming a prospective energy storage technique, due to the abundant potassium resources in the earth crust, approximate redox potential and similar electrochemical behavior of potassium and lithium. However, the insufficient capacity, poor stability and volume expansion of electrode materials during charge and discharge are main factors restricting the further development of KIBs. This work reports an amorphous carbon coated SnO2 nanohseets on hard carbon hollow spheres (AC/SnO2@HCHS) anode with enhanced potassium storage performance. The HCHS acts as a carrier for SnO2 nanosheets, providing high electrical conductivity and stable skeleton. The self-assembled SnO2 nanosheets with high surface area ensures sufficient contact with the electrolyte. Amorphous carbon wrapping can not only relieve SnO2 volume expansion but also provide surface-induced capacitive capacity. As a consequence, the AC/SnO2@HCHS anode presents excellent potassium-ion storage performance with high discharge capacity of 346 mAh g-1 at 0.1 A g-1 over 200 cycles, ultra-long cycling lifetime and outstanding rate capability (236 mAh g-1 at 1 A g-1 over 1000 cycles).

Flexible N doped carbon/bubble-like MoS2 core/sheath framework: Buffering volume expansion for potassium ion batteries.

Suitable anode materials for potassium ion batteries (KIBs) with high capacity, good reversibility and stable cycling performances are still in large demand. Here, flexible N doped carbon/bubble-like MoS2 core/sheath framework (MoS2/NCS) is prepared as an anode material for potassium ion batteries. The N doped carbon sponge (NCS) skeleton with good conductivity and high surface area guarantees superior rate capability and high stability of MoS2/NCS anode. The chemical bonds (CMo) firmly bridge MoS2 and NCS together, which further ensures MoS2/NCS stable cycling performance. More importantly, volume expansion is greatly buffered during cycling by this unique structure: the voids between bubble-like MoS2 sheath and NCS core can effectively buffer volume expansion generated during potassium intercalation/deintercalation; the enlarged interlayer spacing contribute more space to buffer volume change; the ultrathin nanosheets can shorten the charge diffusion distance and buffer volume change. As a consequence, MoS2/NCS delivers a capacity of 374 mAh g-1 over 200 cycles at 50 mA g-1. Even at 1000 mA g-1, a capacity of 212 mAh g-1 can still be obtained over 1000 cycles. We believe this MoS2/NCS structure will highlight the potential of MoS2 in practical KIBs applications.

Metallic Octahedral CoSe2 Threaded by N-Doped Carbon Nanotubes: A Flexible Framework for High-Performance Potassium-Ion Batteries.

Due to the abundant and low-cost K resources, the exploration of suitable materials for potassium-ion batteries (KIBs) is advancing as a promising alternative to lithium-ion batteries. However, the large-sized and sluggish-kinetic K ions cause poor battery behavior. This work reports a metallic octahedral CoSe2 threaded by N-doped carbon nanotubes as a flexible framework for a high-performance KIBs anode. The metallic property of CoSe2 together with the highly conductive N-doped carbon nanotubes greatly accelerates the electron transfer and improves the rate performance. The carbon nanotube framework serves as a backbone to inhibit the agglomeration, anchor the active materials, and stabilize the integral structure. Every octahedral CoSe2 particle arranges along the carbon nanotubes in sequence, and the zigzag void space can accommodate the volume expansion during cycling, therefore boosting the cycling stability. Density functional theory is also employed to study the K-ion intercalation/deintercalation process. This unique structure delivers a high capacity (253 mAh g-1 at 0.2 A g-1 over 100 cycles) and enhanced rate performance (173 mAh g-1 at 2.0 A g-1 over 600 cycles) as an advanced anode material for KIBs.

Piezoelectric and Triboelectric Dual Effects in Mechanical-Energy Harvesting Using BaTiO3/Polydimethylsiloxane Composite Film.

Piezoelectric and triboelectric nanogenerators have been developed as rising energy-harvesting devices in the past few years to effectively convert mechanical energy into electricity. Here, a novel hybrid piezo/triboelectric nanogenerator based on BaTiO3 NP/PDMS composite film was developed in a simple and low-cost way. The effects of the BTO content and polarization degree on the output performance were systematically studied. The device with 20 wt % BTO in PDMS and a 100-µm-thick film showed the highest output power. We also designed three measurement modes to record hybrid, triboelectric, and piezoelectric outputs separately with a simple structure that has only two electrodes. The hybrid output performance is higher than the tribo- and piezoelectric performances. This work will provide not only a new way to enhance the output power of nanogenerators, but also new opportunities for developing built-in power sources in self-powered electronics.