Understanding the Thermal Treatment Effect of Two-Dimensional Siloxene Sheets and the Origin of Superior Electrochemical Energy Storage Performances

Silicene-Based Quantum Dots Nanocomposite Coated Functional UV Protected Textiles With Antibacterial and Antioxidant Properties: A Versatile Solution for Healthcare and Everyday Protection

The predominant adverse health effects in care delivery result from hospital-acquired (nosocomial) infections, which impose a substantial financial burden on global healthcare systems. Integrating contact-killing antibacterial action, gas permeability, and antioxidant properties into textile coatings offers a transformative solution, significantly enhancing both medical and everyday protective applications. This study presents an innovative, pollution-free physical compounding method for creating a fluorescent biopolymer composite embedded with silicene-based heteroatom-doped carbon quantum dots for the production of functional textiles. The resulting coated fabric shows superior ultraviolet (UV) protection behavior (UVA and UVB), thermal stability, breathability, mechanical strength, and antioxidant capabilities as demonstrated by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) experiment (>78%) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) ABTS assay (>90%). Rigorous testing against both gram positive and gram negative bacteria confirms that the coated fabric has excellent antibacterial activity. Results from time-dependent antibacterial assays indicate that the nanocomposite can markedly inhibit bacterial proliferation within a few hours. Molecular dynamics modeling, in conjunction with experimental investigations, is employed to elucidate the intermolecular interactions influencing the components of the treated cotton fabrics. The ongoing research can result in the creation of cost-effective smart textile substrates aimed at inhibiting microbial contamination in healthcare and medical applications, possibly rendering them commercially viable.

Holey etching strategy of siloxene nanosheets to improve the rate performance of photo-assisted Li-O2 batteries

Improving the rate performance is of great significance to achieve high-performance photo-assisted Li-O2 batteries for developing new optimized bifunctional photocatalysts. Herein, a holey etching strategy is developed to prepare porous siloxene nanosheets with a size of 10 nm and few layers (P-siloxene NSs) by a modified Ag+-assisted chemical etching method, and the optimized pore-forming conditions are: Ag+ ion concentration 0.01 mol dm-3, HF concentration 0.565 mol dm-3, and H2O2 concentration 0.327 mol dm-3. By using P-siloxene NSs with a bandgap of 2.77 eV as a novel bifunctional photo-assisted Li-O2 system, the rate performance of the assembled P-siloxene NSs photo-assisted Li-O2 batteries is clearly improved. At a current density of 0.1 mA cm-2, the system shows a low overpotential of 0.35 V, full discharge capacity of 3270 mA h g-1, and 69% round-trip efficiency at 100 cycles. In particular, at a current density of 0.8 mA cm-2, the P-siloxene NSs photo-assisted Li-O2 batteries still give a relatively good charge potential of 3.66 V and a discharge potential of 2.97 V. This work provides a new approach for improving the rate performance of photo-assisted Li-O2 systems and will open up opportunities for the high-efficiency utilization of solar energy in electric systems.

Faster and Safer "In situ" Synthesis of Germanane and Silicane

Germanane (GeH) and silicane (SiH), members of the Xanes family, have garnered significant attention as 2D materials due to their diverse properties, which hold promise for applications in electronics, optoelectronics, energy storage, and sensing. Typically, highly concentrated hydrochloric acid (HCl) or hydrofluoric acid (HF) is employed in the synthesis of these Xanes, but both routes are problematic due to slow kinetics and safety concerns, respectively. Here for the first time, a faster and safer method is demonstrated for Xanes synthesis that harnesses the generation of HF "in situ" using a solution of HCl and lithium fluoride (LiF) salt, overcoming the key challenges of the conventional methods. A variety of characterization techniques to establish a baseline is utilized for both Xanes and to provide a holistic knowledge regarding this method, the possible consequences of this approach, and the possibility of applying it to other layered Zintl phases. The novel synthesis protocol results in high-quality GeH and SiH with bandgaps (Eg) of 1.75 and 2.47 eV respectively, highlighting their potential suitability for integration into semiconductor applications.

Boosted Lithium-Ion Transport Kinetics in n-Type Siloxene Anodes Enabled by Selective Nucleophilic Substitution of Phosphorus

Doped two-dimensional (2D) materials hold significant promise for advancing many technologies, such as microelectronics, optoelectronics, and energy storage. Herein, n-type 2D oxidized Si nanosheets, namely n-type siloxene (n-SX), are employed as Li-ion battery anodes. Via thermal evaporation of sodium hypophosphite at 275 °C, P atoms are effectively incorporated into siloxene (SX) without compromising its 2D layered morphology and unique Kautsky-type crystal structure. Further, selective nucleophilic substitution occurs, with only Si atoms being replaced by P atoms in the O3≡Si-H tetrahedra. The resulting n-SX possesses two delocalized electrons arising from the presence of two electron donor types: (i) P atoms residing in Si sites and (ii) H vacancies. The doping concentrations are varied by controlling the amount of precursors or their mean free paths. Even at 2000 mA g-1, the n-SX electrode with the optimized doping concentration (6.7 × 1019 atoms cm-3) delivers a capacity of 594 mAh g-1 with a 73% capacity retention after 500 cycles. These improvements originate from the enhanced kinetics of charge transport processes, including electronic conduction, charge transfer, and solid-state diffusion. The approach proposed herein offers an unprecedented route for engineering SX anodes to boost Li-ion storage.

Topochemically prepared tungsten disulfide nanostructures as a novel pseudocapacitive electrode for high performance supercapacitor

The topochemical preparation of nanostructured materials (NMs) has received significant attention in recent years due to the exceptional electrochemical properties exhibited by the resulting NMs. This work focuses on the preparation of two-dimensional tungsten di-sulfide (WS2) nanostructures through the topochemical conversion of tungsten trioxide (WO3) nanostructures and also evaluates their potential applications as electrode materials for supercapacitors (SCs). The X-ray diffraction and photoelectron studies conducted in this research reveal the conversion of hexagonal WO3 into hexagonal WS2 nanosheets, accompanied by changes in oxidation states. The FE-SEM and HR-TEM studies confirm the formation of WS2 in the sheet-like morphologies with lateral dimensions of 100 × 100 nm. The electrochemical investigation, using techniques such as CV, galvanostatic CD, and EIS, confirmed the presence of intercalation pseudocapacitance in the WS2 electrode, with a higher electrode-specific-capacitance (260 F g-1) than that of WO3 electrode. The WS2 symmetric SC delivered high device capacitance (59.17 F g-1), energy density (8.21 Wh kg-1) and power density (3,750 W kg-1) with better cyclic stability over 5000 cycles. These experimental findings show that the topochemically synthesized WS2as novel supercapacitor electrodes might be useful for the advancement of future-generation energy storage devices.

Scalable Solution Phase Synthesis of 2D Siloxene via a Two-Step Interlayer Expansion Process

Two-dimensional (2D) siloxene is attracting considerable research interest recently principally owing to its inherent compatibility with silicon-based semiconductor technology. -The synthesis of siloxene has been mostly limited to multilayered structures using traditional topochemical reaction procedures. Herein, we report high-yield synthesis of single to few-layer siloxene nanosheets by developing a two-step interlayer expansion and subsequent liquid phase exfoliation procedure. Our protocol enables high-yield production of few-layer siloxene nanosheets with a lateral dimension of up to 4 μm and thickness ranging from 0.8 to 4.8 nm, corresponding to single to a few layers, well stabilized in water. The atomically flat nature of exfoliated siloxene can be exploited for the construction of 2D/2D heterostructure membranes via typical solution processing. We demonstrate highly ordered graphene/siloxene heterostructure films with synergistic mechanical and electrical properties, which deliver noticeably high device capacitance when assembled into a coin cell symmetric supercapacitor device structures. Additionally, we demonstrate that the mechanically flexible exfoliated siloxene-graphene heterostructure enables its direct use in flexible and wearable supercapacitor applications.

Two-Dimensional Siloxene Nanosheets: Impact of Morphology and Purity on Electrochemistry

Two-dimensional (2D) siloxene (Si₆O₃H₆) has shown promise as a negative electrode material for Li-ion batteries due to its high gravimetric capacity and superior mechanical properties under (de)lithiation compared to bulk Si. In this work, we prepare purified siloxene nanosheets through the removal of bulk Si contaminants, use ultrasonication to control the lateral size and thickness of the nanosheets, and probe the effects of the resulting morphology and purity on the electrochemistry. The thin siloxene nanosheets formed after 4 h of ultrasonication deliver an average capacity of 810 mA h/g under a 1000 mA/g rate over 200 cycles with a capacity retention of 76%. Interestingly, the purified siloxene shows lower initial capacity but superior capacity retention over extended cycling. The 2D morphology benefit is illustrated where the parent siloxene nanosheet morphology and structure were largely maintained based on operando optoelectrochemistry, in situ Raman, ex situ scanning electron microscopy, and ex situ transmission electron microscopy. Furthermore, the purified siloxene-based electrode free from crystalline Si impurity experiences the least expansion upon (de)lithiation as visualized by cross-section electron microscopy of samples recovered post-cycling.

Siloxene Nanosheets and Their Hybrid Gel Glasses for Broad-Band Optical Limiting

With the development of laser technology, the research of novel laser protection materials is of great significance. In this work, dispersible siloxene nanosheets (SiNSs) with a thickness of about 1.5 nm are prepared by the top-down topological reaction method. Based on the Z-scan and optical limiting testing under the visible-near IR ranges nanosecond laser, the broad-band nonlinear optical properties of the SiNSs and their hybrid gel glasses are investigated. The results show that the SiNSs have outstanding nonlinear optical properties. Meanwhile, the SiNSs hybrid gel glasses also exhibit high transmittance and excellent optical limiting capabilities. It demonstrates that SiNSs are promising materials for broad-band nonlinear optical limiting and even have potential applications in optoelectronics.

Bifunctional Photoassisted Li-O2 Battery with Ultrahigh Rate-Cycling Performance Based on Siloxene Size Regulation

Directly integrating the bifunctional photoelectrode into Li-O2 batteries has been considered an effective way to reduce the overpotential and promote electric energy saving. However, more regular investigations on various bifunctional photocatalysts have still been desired for high-performance photoassisted Li-O2 batteries. Herein, a systematic exploration of various-sized siloxene photocatalysts affected by Li-O2 batteries has been introduced. Compared with the utilization of larger-sized siloxene nanosheets (SNSs), the photoassisted Li-O2 battery with a siloxene quantum dot (SQD) photoelectrode delivers a superior round-trip efficiency of 230% based on the highest discharge potential up to 3.72 V and lowest charge potential of 1.60 V and enables the maintenance of a long-term cycling life with only 13% efficiency attenuation after 200 cycles at 0.075 mA/cm2. Furthermore, this system exhibits a record-high rate-cycling performance (162% round-trip efficiency, even at 3 mA/cm2) and a high discharge capacity of 2212 mAh/g at 1 mA/cm2. These ground-breaking performances could be attributed to the synergistic effect of the photocatalytic and electrocatalytic activities of SQD photocatalysts with the ideal conduction band/valence band values, the abundant defective sites, and the stronger O2 and lower LiO2 adsorption strengths of SQD photocatalysts. These systematic research studies highlight the significance of SQD bifunctional photocatalysts and could be extended to other photocatalysts for further high-efficiency photoelectric conversion and storage.

High surface area siloxene for photothermal and electrochemical catalysis

Catalysis based on two-dimensional silicon has been under intense investigation recently. However, its substandard catalytic activity is far from industrialization. In this work, we demonstrate a new solution to this problem formulated on the batch synthesis of siloxene with an enhanced specific surface area (217.8 m² g^-1). A two-dimensional porous structure was prepared, enabling great support and dispersion of metal nanoparticles. Catalytic evaluations of such hybrid structures for the (photo)thermal CO₂ hydrogenation reaction and the electrochemical hydrogen evolution reaction revealed a significant performance advantage over the benchmark two-dimensional silicon structures synthesized via the conventional method. This work may confer notable viability on two-dimensional silicon for advanced energy, catalytic, and environmental applications.

Accommodation of Two-Dimensional SiOx in a Point-to-Plane Conductive Network Composed of Graphene and Nitrogen-Doped Carbon for Robust Lithium Storage

Silicon oxides (SiO_x) are one of the most promising anode materials for next-generation lithium-ion batteries owing to their abundant reserve and low lost and high reversible capacity. However, the practical application of SiO_x is still hindered by their intrinsically low conductivity and huge volume change. In this regard, we design a novel anode material in which sheet-like SiO_x nanosheets are encapsulated in a unique point-to-plane conductive network composed of graphene flakes and nitrogen-doped carbon spheres. This unique composite structure demonstrates high specific capacity (867.7 mAh g^-1 at 0.1 A g^-1), superior rate performance, and stable cycle life. The electrode delivers a superior reversible discharge capacity of 595.8 mAh g^-1 after 200 cycles at 1.0 A g^-1 and 287.5 mAh g^-1 after 500 cycles at 5.0 A g^-1. This work may shed light on the rational design of SiO_x-based anode materials for next-generation high-performance lithium-ion batteries.

Siloxene-Functionalized Laser-Induced Graphene via COSi Bonding for High-Performance Heavy Metal Sensing Patch Applications

Here, 2D Siloxene nanosheets are newly applied to functionalize porous laser-induced graphene (LIG) on polydimethylsiloxane, modify the surface chemical properties of LIG, and improve the heterogeneous electron transfer rate. Meanwhile, the newly generated COSi crosslink boosts the binding of LIG and Siloxene. Thus, the Siloxene/LIG composite is used as the basic electrode material for the multifunctional detection of copper (Cu) ions, pH, and temperature in human perspiration. Moreover, to enhance the sensing performance of Cu ions, Siloxene/LIG is further modified by carbon nanotubes (CNTs). The fabricated Siloxene-CNT/LIG-based Cu-ion sensor shows linear response within a wide range of 10-500 ppb and a low detection limit of 1.55 ppb. In addition, a pH sensor is integrated to calibrate for determining the accurate concentration of Cu ions due to pH dependency of the Cu-ion sensor. The polyaniline-deposited pH sensor demonstrates a good sensitivity of -64.81 mV pH^-1 over the pH range of 3-10. Furthermore, a temperature sensor for accurate skin temperature monitoring is also integrated and exhibits a stable linear resistance response with an excellent sensitivity of 9.147 Ω °C^-1 (correlation coefficient of 0.139% °C^-1 ). The flexible hybrid sensor is promising in applications of noninvasive heavy-metal ion detection and prediction of related diseases.

Ultrastable and High-Rate 2D Siloxene Anode Enabled by Covalent Organic Framework Engineering for Advanced Lithium-Ion Batteries

Siloxene as a new type of 2D material has wide potential applications due to its special structure. Especially, as anode for lithium-ion batteries, siloxene shows promising prospect due to its small volume change and low diffusion pathway. However, the unstable solid electrolyte interphase and low electronic conductivity lead to the low Coulombic efficiency, poor rate capability, and limited cycling performance. To settle the problems, a thin porous covalent organic framework (COF) coating layer is designed by in situ growth on micro-sized siloxene. With the inherent ionic conductive and electrolyte compatible advantages of COF, the engineered siloxene demonstrates superior electrochemical performance with 96% capacity retention at 8 A g^-1 for 1500 cycles.

Passion fruit-like microspheres of FeS2 wrapped with carbon as excellent fast charging materials for supercapacitors

Pyrite (FeS2) has attracted growing attention as pseudocapacitance electrode materials for supercapacitors. However, the fast capacity fading and the poor cycling performance, greatly hinder its practical application. Herein, a facile...

Nickel-Cobalt Hydroxides with Tunable Thin-Layer Nanosheets for High-Performance Supercapacitor Electrode

Layered double hydroxides as typical supercapacitor electrode materials can exhibit superior energy storage performance if their structures are well regulated. In this work, a simple one-step hydrothermal method is used to prepare diverse nickel-cobalt layered double hydroxides (NiCo-LDHs), in which the different contents of urea are used to regulate the different nanostructures of NiCo-LDHs. The results show that the decrease in urea content can effectively improve the dispersibility, adjust the thickness and optimize the internal pore structures of NiCo-LDHs, thereby enhancing their capacitance performance. When the content of urea is reduced from 0.03 to 0.0075 g under a fixed precursor materials mass ratio of nickel (0.06 g) to cobalt (0.02 g) of 3:1, the prepared sample NiCo-LDH-1 exhibits the thickness of 1.62 nm, and the clear thin-layer nanosheet structures and a large number of surface pores are formed, which is beneficial to the transmission of ions into the electrode material. After being prepared as a supercapacitor electrode, the NiCo-LDH-1 displays an ultra-high specific capacitance of 3982.5 F g^-1 under the current density of 1 A g^-1 and high capacitance retention above 93.6% after 1000 cycles of charging and discharging at a high current density of 10 A g^-1. The excellent electrochemical performance of NiCo-LDH-1 is proved by assembling two-electrode asymmetric supercapacitor with carbon spheres, displaying the specific capacitance of 95 F g^-1 at 1 A g^-1 with the capacitance retention of 78% over 1000 cycles. The current work offers a facile way to control the nanostructure of NiCo-LDHs, confirms the important affection of urea on enhancing capacitive performance for supercapacitor electrode and provides the high possibility for the development of high-performance supercapacitors.

Ultra-Large Sized Siloxene Nanosheets as Bifunctional Photocatalyst for a Li-O2 Battery with Superior Round-Trip Efficiency and Extra-Long Durability

Developing new optimized bifunctional photocatalyst is of great significant for achieving the high-performance photo-assisted Li-O₂ batteries. Herein, a novel bifunctional photo-assisted Li-O₂ system is constructed by using siloxene nanosheets with ultra-large size and few-layers due to its superior light harvesting, semiconductor characteristic, and low recombination rate. An ultra-low charge potential of 1.90 V and ultra-high discharge of 3.51 V have been obtained due to the introduction of this bifunctional photocatalyst into Li-O₂ batteries, and these results have realized the round-trip efficiency up to 185 %. In addition, this photo-assisted Li-O₂ batteries exhibits a high rate (129 % round-trip efficiency at 1 mA cm^-2 ), a prolonged cycling life with 92 % efficiency retention after 100 cycles, and the highly reversible capacity of 1170 mAh g^-1 at 0.75 mA cm^-2 . This work will open the vigorous opportunity for high-efficiency utilization of solar energy into electric system.

In situ carbon-supported titanium dioxide (ICS-TiO2) as an electrode material for high performance supercapacitors

Supercapacitors have attracted significant attention in the last few years as they have the capability to fulfill the demand for both power and energy density in many energy storage applications. In this study, an in situ carbon-supported titanium oxide (ICS-TiO2) electrode has been prepared using sucrose and TiO2 powder. The ICS-TiO2 powder was prepared by slipcasting, followed by the annealing of the TiO2 slurry. Sucrose was added to the TiO2 slurry as a soluble carbon source, and was converted into carbon at 600 °C then coated on the TiO2 particles. The morphological and structural evolution of the electrode was investigated by FEG-SEM, FEG-TEM, XRD, BET, FTIR, XPS and Raman spectroscopy. The electrochemical characterization of ICS-TiO2 demonstrated that this material exhibits an efficient value of specific capacitance (277.72 F g-1 at 25 mV s-1) for charge storage. ISC-TiO2 also exhibits a specific capacitance of 180 F g-1 at 2 A g-1 in a 1 M Na2SO4 aqueous electrolyte. The results suggest that ICS-TiO2 can be utilized as a high-performance electrode material for supercapacitors with desirable electrochemical properties.

Probing the energy conversion process in piezoelectric-driven electrochemical self-charging supercapacitor power cell using piezoelectrochemical spectroscopy

The design and development of self-charging supercapacitor power cells are rapidly gaining interest due to their ability to convert and store energy in an integrated device. Here, we have demonstrated the fabrication of a self-charging supercapacitor using siloxene sheets as electrodes and siloxene-based polymeric piezofiber separator immobilized with an ionogel electrolyte. The self-charging properties of the fabricated device subjected to various levels of compressive forces showed their ability to self-charge up to a maximum of 207 mV. The mechanism of self-charging process in the fabricated device is discussed via "piezoelectrochemical effect" with the aid of piezoelectrochemical spectroscopy measurements. These studies revealed the direct evidence of the piezoelectrochemical phenomenon involved in the energy conversion and storage process in the fabricated device. This study can provide insight towards understanding the energy conversion process in self-charging supercapacitors, which is of significance considering the state of the art of piezoelectric driven self-charging supercapacitors.

Free-Standing PVDF/Reduced Graphene Oxide Film for All-Solid-State Flexible Supercapacitors towards Self-Powered Systems

The development of polymer-based devices has attracted much attention due to their miniaturization, flexibility, lightweight and sustainable power sources with high efficiency in the field of wearable/portable electronics, and energy system. In this work, we proposed a polyvinylidene fluoride (PVDF)-based composite matrix for both energy harvesting and energy storage applications. The physicochemical characterizations, such as X-ray diffraction, laser Raman, and field-emission scanning electron microscopy (FE-SEM) analyses, were performed for the electrospun PVDF/sodium niobate and PVDF/reduced graphene oxide composite film. The electrospun PVDF/sodium niobate nanofibrous mat has been utilized for the energy harvester which shows an open circuit voltage of 40 V (peak to peak) at an applied compressive force of 40 N. The PVDF/reduced graphene oxide composite film acts as the electrode for the symmetric supercapacitor (SSC) device fabrication and investigated for their supercapacitive properties. Finally, the self-charging system has been assembled using PVDF/sodium niobate (energy harvester), and PVDF/reduced graphene oxide SSC (energy storage) and the self-charging capability is investigated. The proposed self-charging system can create a pathway for the all-polymer based composite high-performance self-charging system.

Spontaneous deposition of Ir nanoparticles on 2D siloxene as a high-performance HER electrocatalyst with ultra-low Ir loading

Based on the reducibility of siloxene, Ir nanoparticles were spontaneously deposited on siloxene and showed excellent performance for the HER.

Hydrothermally synthesized chalcopyrite platelets as an electrode material for symmetric supercapacitors

A novel chalcopyrite (CuFeS₂) platelet like open-pored micro-flower nanostructure investigated as an electrode material for supercapacitors.

Supercapacitive properties of amorphous MoS3 and crystalline MoS2 nanosheets in an organic electrolyte

Amorphous-MoS₃ and crystalline-MoS₂ prepared via thermal decomposition of ammonium tetrathiomolybdate and their electrochemical energy-storage properties reveals better capacitive and charge-transfer nature for MoS₂ SSC over amorphous-MoS₃ SSC.