Chitosan-assisted fabrication of ultrathin MoS2/graphene heterostructures for Li-ion battery with excellent electrochemical performance

A 2D hybrid nanocomposite: a promising anode material for lithium-ion batteries at high temperature

Two-dimensional atomically thick materials including graphene, BN, and molybdenum disulfide (MoS2) have been investigated as possible energy storage materials, because of their large specific surface area, potential redox activity, and mechanical stability. Unfortunately, these materials cannot reach their full potential due to their low electrical conductivity and layered structural restacking. These problems have been somewhat resolved in the past by composite electrodes composed of a graphene and MoS2 mixture; however, insufficient mixing at the nanoscale still limits performance. Here, we examined lithium-ion battery electrodes and reported three composites made using a basic ball milling technique and sonication method. The 5% BN-G@MoS2-50@50 composite obtained has a homogeneous distribution of MoS2 on the graphene sheet and H-BN with high crystallinity. Compared to the other two composites (5% BN-G@MoS2-10@90 and 5% BN-G@MoS2-90@10), the 5% BN-G@MoS2-50@50 composite electrode exhibits a high specific capacity of 765 mA h g-1 and a current density of 100 mA g-1 in batteries. Additionally, the 5% BN-G@MoS2-50@50 composite electrode displays an excellent rate capability (453 mA h g-1 at a current density of 1000 mA g-1) at a high temperature of 70 °C, thanks to h-BN that allows reliable and safe operation of lithium-ion batteries. Our research may pave the way for the sensible design of different anode materials, including 2D materials (5% BN-G@MoS2-50@50) for high-performance LIBs and other energy-related fields.

Synergistic Charge Storage Enhancement in Supercapacitors via Ti3C2Tx MXene and CoMoO4 Nanoparticles

MXene has emerged as a highly promising two-dimensional (2D) layered material with inherent advantages as an electrode material, such as a high electrical conductivity and spacious layer distances conducive to efficient ion transport. Despite these merits, the practical implementation faces challenges due to MXene's low theoretical capacitance and issues related to restacking. In order to overcome these limitations, we undertook a strategic approach by integrating Ti3C2Tx MXene with cobalt molybdate (CoMoO4) nanoparticles. The CoMoO4 nanoparticles bring to the table rich redox activity, high theoretical capacitance, and exceptional catalytic properties. Employing a facile hydrothermal method, we synthesized CoMoO4/Ti3C2Tx heterostructures, leveraging urea as a size-controlling agent for the CoMoO4 precursors. This innovative heterostructure design utilizes Ti3C2Tx MXene as a spacer, effectively mitigating excessive agglomeration, while CoMoO4 contributes its enhanced redox reaction capabilities. The resulting CoMoO4/Ti3C2Tx MXene hybrid material exhibited 698 F g-1 at a scan rate of 5 mV s-1, surpassing that of the individual pristine Ti3C2Tx MXene (1.7 F g-1) and CoMoO4 materials (501 F g-1). This integration presents a promising avenue for optimizing MXene-based electrode materials, addressing challenges and unlocking their full potential in various applications.

Molybdenum Oxynitride Atomic Nanoclusters Bonded in Nanosheets of N-Doped Carbon Hierarchical Microspheres for Efficient Sodium Storage

Transition metal nitrides have attracted considerable attention as great potential anode materials due to their excellent metallic conductivity and high theoretical specific capacity. However, their cycling performance is impeded by their instability caused by the reaction mechanism. Herein, we report the engineering and synthesis of a novel hybrid architecture composed of MoO_2.0N_0.5 atomic nanoclusters bonded in nanosheets of N-doped carbon hierarchical hollow microspheres (MoO_2.0N_0.5/NC) as an anode material for sodium-ion batteries. The facile self-templating strategy for the synthesis of MoO_2.0N_0.5/NC involves chemical polymerization and subsequent one-step calcination treatments. The design is beneficial to improve the electrochemical kinetics, buffer the volume variation of electrodes during cycling, and provide more interfacial active sites for sodium uptake. Due to these unique structural and compositional merits, these MoO_2.0N_0.5/NC exhibits excellent sodium storage performance in terms of superior rate capability and stable long cycle life. The work shows a feasible and effective way to design novel host candidates and solve the long-term cycling stability issues for sodium-ion batteries.

TEMPO-oxidized nanofibrillated cellulose assisted exfoliation of MoS2/graphene composites for flexible paper-anodes

TEMPO-oxidized nanofibrillated cellulose (ONFC) with charged carboxyl groups is introduced for the efficient exfoliation of two-dimensional (2D) MoS2/graphene composites. As an effective dispersant agent, ONFC can be easily absorbed between the adjacent layers, so as to prevent the accumulation of the exfoliated nanosheets. With the assistance of charged ONFC, the exfoliated MoS2/graphene is gradually increased in the aqueous dispersions with the elongated sonication time. After dewatering, self-standing MoS2/Graphene/ONFC/CNTs composite films are rationally constructed using ONFC as flexible fibrous skeleton, and CNTs/graphene as 1D/2D interpenetrating electrical networks. Ultrathin MoS2 nanosheets anchored on the 1D/2D heterogeneous networks is directly acted as an ideal paper-anode for lithium-ion batteries (LIBs) without using traditional metallic current collector. The self-standing flexible electrode materials based on natural cellulose will promote the future green electronics with high flexibility, miniaturization, and increased portability.

Recent Advances in Chitin and Chitosan/Graphene-Based Bio-Nanocomposites for Energetic Applications

Herein, we report recent developments in order to explore chitin and chitosan derivatives for energy-related applications. This review summarizes an introduction to common polysaccharides such as cellulose, chitin or chitosan, and their connection with carbon nanomaterials (CNMs), such as bio-nanocomposites. Furthermore, we present their structural analysis followed by the fabrication of graphene-based nanocomposites. In addition, we demonstrate the role of these chitin- and chitosan-derived nanocomposites for energetic applications, including biosensors, batteries, fuel cells, supercapacitors and solar cell systems. Finally, current limitations and future application perspectives are entailed as well. This study establishes the impact of chitin- and chitosan-generated nanomaterials for potential, unexplored industrial applications.

Synthesis of biogenic chitosan-functionalized 2D layered MoS2 hybrid nanocomposite and its performance in pharmaceutical applications: In-vitro antibacterial and anticancer activity

A bacterial and viral infection causes life threatening diseases owing to the abuse of antibiotics and the development of antibiotic resistance microbes. Currently, biopolymers have been considered as the most promising materials in the medical field. Herein, the biogenic chitosan-functionalized MoS₂ nanocomposite was prepared by the hydrothermal method with the liquid exfoliation process. The X-ray diffraction (XRD) results of chitosan-MoS₂ hybrid nanocomposite revealed that MoS₂ nanoparticle was found to be 42 nm with a hexagonal crystal structure. FTIR and Raman spectrum revealed that the nitrogen functionalities in the chitosan interacted with MoS₂ to form the nanocomposite. The XPS spectrum of chitosan-MoS₂ nanocomposite confirms that C, N, O, Mo, and S exist in the nanocomposite. Thermal gravimetric analysis (TGA) and Differential thermal analysis (DTA) analysis showed that the chitosan-MoS₂ nanocomposite has higher thermal stability up to 600 °C. In the antibacterial application the chitosan-MoS₂ hybrid nanocomposite shows zones of inhibition against S. aureus as 22, 28, and 32 mm, and against E. coli as 26, 30, and 35 mm. In the anticancer analysis, chitosan-MoS₂ hybrid nanocomposites showed a maximum cell inhibition of 65.45% at 100 μg/mL^-1, resulting in the most significant MCF-7 cell inhibition.

Highly effective remediation of Pb(II) and Hg(II) contaminated wastewater and soil by flower-like magnetic MoS2 nanohybrid

The efficient enrichment and remediation of heavy metals from realistic wastewater and contaminated soil containing large excess of competitive ions remains a daunting challenge by far. In the present study, flower-like molybdenum disulfide decorated with iron oxide nanoparticles (MoS₂/Fe₃O₄) is designed via a two-step hydrothermal method and mainly applied in the removal of Hg(II) and Pb(II) ions in aqueous environment. Exhaustive morphological, chemical and magnetic characterizations verify the successful formation of magnetic MoS₂/Fe₃O₄. Batch adsorption experiments show that the obtained MoS₂/Fe₃O₄ nanohybrid enables efficient capture of Hg(II) and Pb(II) ions, accompanied by ease-of-separation from solution by simply applying a magnet. In this respect, high adsorption capacities (263.6 mg g^-1 for Pb(II) and 428.9 mg g^-1 for Hg(II)) can be gained under optimized conditions (pH = 5.0; 298 K; nanohybrid dosage: 0.8 g L^-1 and the contact time: 180 min). In addition, the effects of different parameters such as initial Pb(II)/Hg(II) concentration (50-500 mg L^-1), temperature (298, 308 and 318 K) and co-existing ions (Zn(II), Cu(II), Cd(II) and Mg(II)) were systematically probed. The favorable adsorption capacity, selectivity and recyclability mainly originates from the strong Hg²⁺/Pb²⁺···S^2- bonding interactions. Practical application potential of magnetic MoS₂/Fe₃O₄ nanohybrid in realistic lead-acid battery industry wastewater and Pb(II)-contaminated soil is further explored, achieving promising results with high Pb(II) removal efficiency of 99.63% for wastewater and 57.15% for soil. Simple preparation, easy separation and high adsorption capacity would foster thus-designed sulfide-based nanohybrid a promising adsorbent for heavy metal removal from wastewater and contaminated soil.

Metal-Semiconductor Phase Twinned Hierarchical MoS2 Nanowires with Expanded Interlayers for Sodium-Ion Batteries with Ultralong Cycle Life

Sodium-ion batteries (SIBs) are considered a prospective candidate for large-scale energy storage due to the merits of abundant sodium resources and low cost. However, a lack of suitable advanced anode materials has hindered further applications. Herein, metal-semiconductor mixed phase twinned hierarchical (MPTH) MoS₂ nanowires with an expanded interlayer (9.63 Å) are engineered and prepared using MoO₃ nanobelts as a self-sacrificed template in the presence of a trace amount of (NH₄ )₆ Mo₇ O₂₄ ·4H₂ O as initiator. The greatly expanded interlayer spacing accelerates Na⁺ insertion/extraction kinetics, and the metal-semiconductor mixed phase enhances electron transfer ability and stabilizes electrode structure during cycling. Benefiting from the structural merits, the MPTH MoS₂ electrode delivers high reversible capacities of 200 mAh g^-1 at 0.1 A g^-1 for 200 cycles and 154 mAh g^-1 at 1 A g^-1 for 2450 cycles in the voltage range of 0.4-3.0 V. Strikingly, the electrode maintains 6500 cycles at a current density of 2 A g^-1 , corresponding to a capacity retention of 82.8% of the 2nd cycle, overwhelming the all reported MoS₂ cycling results. This study provides an alternative strategy to boost SIB cycling performance in terms of reversible capacity by virtue of interlayer expansion and structure stability.

Differential pulse voltammetric determination of the carcinogenic diamine 4,4'-oxydianiline by electrochemical preconcentration on a MoS2 based sensor

An electrochemical sensor for the carcinogen 4,4'-oxydianiline (Oxy) is described. The method is based on the ability of MoS₂ nanosheets to preconcentrate Oxy. A glassy carbon electrode (GCE) was covered, by drop-casting, with MoS₂ nanosheets that were obtained by exfoliation. X-Ray photoemission spectroscopy indicates that Oxy accumulates on the MoS₂ nanosheets through an electropolymerization process similar to that reported for aniline. Both electrochemical impedance spectroscopy and atomic force microscopy were used to characterize the electrode surface at the different stages of device fabrication. Employing the current measured at +0.27 V vs. Ag/AgCl after Oxy adsorption, the modified GCE enables the voltammetric detection of Oxy at 80 nM levels with relative errors and relative standard deviations of <8.3 and <5.6%, respectively, at all the concentrations studied. The method was applied to the selective determination of Oxy in spiked river water samples. Very good selectivity and recoveries of around 95% in average are found. Graphical abstractSchematic representation of 4,4-oxydianiline electrochemical polymerization and preconcentration onto molybdenum disulfide nanosheets for the diamine determination in river waters.

Chitosan-Induced Synthesis of Hierarchical Flower Ridge-like MoS2/N-Doped Carbon Composites with Enhanced Lithium Storage

Continuous hierarchical MoS₂/C micro/nanostructured composite with strong structural stability and efficient lithium ion and electron transport channels is an urgent need for its successful application in lithium ion battery anode materials. In this study, continuous hierarchical flower ridge-like MoS₂/N-doped carbon micro/nanocomposite (MoS₂/NC) was first synthesized through a simple chitosan-induced one-pot hydrothermal and postsintering method. The amino-containing chitosan is demonstrated to be important not only in nitrogen-doped carbon source, soft template, and surfactant but also in controlling the interlayer distance between adjacent MoS₂ layers. The detailed hierarchical structure, phase characteristics, the number of MoS₂ stacked layers, and interlayer distance were characterized using a scanning electron microscope, transmission electron microscope, X-ray diffraction, and so forth. It reveals that the interconnected nanoflowers composed of few-layer MoS₂ (≤3 layers) nanoflakes with an expanded interlayer distance vertically grow on two-dimensional N-doped carbon nanosheets in the MoS₂/NC composite. When examined as anode of lithium ion batteries, this unique hierarchical MoS₂/NC micro/nanostructure shows better electrochemical performance. The electrode delivers a reversible capacity of 904.7 mA h g^-1 at 200 mA g^-1 after 100 cycles, outstanding cycle stability at high rates (742, 686, 534 mA h g^-1 at 500, 1000, 2000 mA g^-1 after 400 cycles, respectively) and superior rate performance. The above synthesis strategy is a good choice for constructing other hierarchical transition-metal disulfides or oxides and carbon micro/nanostructures to improve their electrochemical performance.

Improved Lithium-Ion and Sodium-Ion Storage Properties from Few-Layered WS2 Nanosheets Embedded in a Mesoporous CMK-3 Matrix

An integrated WS₂ @CMK-3 nanocomposite has been prepared by a one-step hydrothermal method and then used as the anode material for lithium-ion and sodium-ion batteries. Ultrathin WS₂ nanosheets have been successfully embedded into the ordered mesoporous carbon (CMK-3) framework. Owing to the few-layered nanostructure of WS₂ , as well as the high electronic conductivity and the volume confinement effect of CMK-3, the material shows larger discharge capacity, better rate capability, and improved cycle stability than pristine WS₂ . When tested in lithium-ion batteries, the material delivers a reversible capacity of 720 mA h g^-1 after 100 cycles at a current density of 100 mA g^-1 . A large discharge capacity of 307 mA h g^-1 is obtained at a current density of 2 A g^-1 . When used in sodium-ion batteries, the material exhibits a capacity of 333 mA h g^-1 at 100 mA g^-1 without capacity fading after 70 cycles. A discharge capacity of 230 mA h g^-1 is obtained at 2 A g^-1 . This excellent performance demonstrates that the WS₂ @CMK-3 nanocomposite has great potential as a high-performance anode material for next-generation rechargeable batteries.

A review of recent progress in molybdenum disulfide-based supercapacitors and batteries

This article reviews the recent progress in molybdenum disulfide-based supercapacitors and batteries.

The novel and facile preparation of multilayer MoS2 crystals by a chelation-assisted sol–gel method and their electrochemical performance

Multilayer molybdenum disulfide was prepared by a chelation-assisted sol–gel method with ammonium molybdate tetrahydrate, thioacetamide and diethylenetriamine pentaacetic acid (Dtpa), followed by calcination.

The synthesis of hollow MoS2 nanospheres assembled by ultrathin nanosheets for an enhanced energy storage performance

Hollow MoS₂ nanospheres with enhanced energy storage performance has been synthesized from core–shell ZnS@MoS₂ nanostructures.

Hierarchical MoS2 tubular structures internally wired by carbon nanotubes as a highly stable anode material for lithium-ion batteries

Molybdenum disulfide (MoS2), a typical two-dimensional material, is a promising anode material for lithium-ion batteries because it has three times the theoretical capacity of graphite. The main challenges associated with MoS2 anodes are the structural degradation and the low rate capability caused by the low intrinsic electric conductivity and large strain upon cycling. Here, we design hierarchical MoS2 tubular structures internally wired by carbon nanotubes (CNTs) to tackle these problems. These porous MoS2 tubular structures are constructed from building blocks of ultrathin nanosheets, which are believed to benefit the electrochemical reactions. Benefiting from the unique structural and compositional characteristics, these CNT-wired MoS2 tubular structures deliver a very high specific capacity of ~1320 mAh g(-1) at a current density of 0.1 A g(-1), exceptional rate capability, and an ultralong cycle life of up to 1000 cycles. This work may inspire new ideas for constructing high-performance electrodes for electrochemical energy storage.

Facile synthesis of ultrathin, undersized MoS2/graphene for lithium-ion battery anodes

Ultrathin (∼5 layers), undersized (130–160 nm in size) MoS₂/graphene composites are fabricated by a facile acetic acid assisted hydrothermal route.