MoS2 Nanopetals Research Articles

Synergistic integration of MoS2 nanopetals and SnO2 quantum dots for enhanced supercapacitor performance

This study presents the synthesis and electrochemical application of MoS2 nanopetals/SnO2 quantum dots (MS/SQD) nanocomposites. Employing a hydrothermal method for MoS2 and a simple mixing process for SnO2 using thiourea and tin chloride dihydrate, we engineered a nanocomposite that significantly enhances supercapacitor performance. Characterization through XRD, FE-SEM, FE-TEM, and XPS confirmed the optimal morphology and structural integrity of the MS/SQD. Electrochemical evaluations using a three-electrode system highlighted the nanocomposite’s exceptional electrochemical attributes: it achieved a specific capacitance of up to 505 F·g−1 at 1 A·g−1 and maintained 350 F·g−1 at a high current density of 10 A·g−1, with nearly 99% capacity retention after 5,000 cycles. The novelty lies in the synergistic effects of SnO2 quantum dots, which enhance the MoS2 nanopetal’s structural integrity, conductivity, and electrochemical reactivity, thereby improving charge transfer efficiency and ion diffusion. These findings underscore the MS/SQD nanocomposite’s potential for high-performance energy storage applications.

Fabrication of MoS2 nanopetals on honeycomb-like biochar with enhanced sonocatalytic activity for degradation of acid blue 7 and pharmaceutical pollutants

Organic dyes constitute an integral part of industrial effluents. Advanced oxidation processes are efficient methods for the degradation of organic pollutants, one of the most promising of which is sonocatalysis. In this study, we aimed to immobilize MoS2 nanopetals on honeycomb-like biochar through a one-step hydrothermal method and evaluate its sonocatalytic performance in the degradation of acid blue 7 (AB7). The MoS2-Biochar composite demonstrated enhanced sonocatalytic activity, approved by its larger specific surface area (5.0 m2/g) and narrower bandgap (1.25 eV) compared with those of pure MoS2. Application of 1.5 g/L MoS2-Biochar (10:1) led to a 95 % decolorization of AB7 (20 mg/L) within 40 min of reaction time. Moreover, considerable degradation efficiencies were achieved for various organic pollutants, including hydroxychloroquine (96 %), levofloxacin (81 %), phenazopyridine (80 %), and tilmicosin (67 %) with initial concentration of 20 mg/L within 120 min of treatment. The synergy factor and degradation turnover value of the sonocatalytic process for decolorization of AB7 were calculated to be 4.88 and 27.37 µmol/h.gcat, respectively. Trapping experiments were conducted to determine the roles of various reactive species in the sonocatalytic degradation process, and holes were found to be the dominant species. Furthermore, the generated intermediates were identified using gas chromatography–mass spectrometry (GC–MS) analysis, which suggested a possible mechanism for the degradation process. A stable structure and acceptable reusability with a 16 % reduction in the decolorization efficiency after four consecutive sonocatalytic runs were observed for the 10:1 composite, suggesting a promising perspective for the application of the studied system in the efficient treatment of organic pollutants.

Hierarchical dessert plant-like CoNiO2 nanowires decoration on MoS2 nano-petals for enhanced bi-functional overall water splitting reactions

To produce hydrogen, overall water splitting is the extremely effective method and their one of the key factors is the fabrication of bifunctional electrode materials with high catalytic activity, rotational design with a high active site, easy mass transfer, stability, and earth abundance. In this work, CoNiO2 nanowires (NWs)-embedded MoS2 hybrids were prepared using the hydrothermal synthesis method. The developed CoNiO2@MoS2 hybrid electrode achieved superior bifunctional catalytic activity with an overpotential of 43 mV and 220 mV for hydrogen evolution and oxygen evolution reactions, respectively, and more than 24 h span stability. Furthermore, the assembled CoNiO2@MoS2║CoNiO2@MoS2 electrocatalyst exhibited an overpotential of 1.47 V for overall splitting process at 10 mA cm−2, with improved electronic conductivity and stability. Density functional theory approximations revealed that the CoNiO2 NWs and MoS2 in the CoNiO2@MoS2 hybrid exhibited a strong interfacial contact, which enabled the preferable ΔGH⁎ and ΔGn values, thus significantly improving the electrocatalytic performance. The development of cobalt-based oxides with transition metal dichalcogenides-carrier bifunctional electrocatalysts will provide a novel approach to enhance overall water splitting.

Novel MoS2/C3N5 composites with extended spectral response towards highly efficient photocatalytic abatement of hazardous pollutants

Carbon nitride materials are one of the potential candidates for photocatalytic application. The present work demonstrates the fabrication of C3N5 catalyst from a simple, low-cost, and easily available nitrogen-containing precursor, melamine. The facile and microwave mediated method was used to prepare novel MoS2/C3N5 composites (referred to as MC) with varying weight ratios (1:1, 1:3, and 3:1). This work provided a novel strategy to improve photocatalytic activity and accordingly fabricated a potential material for effective removal of organic contaminants from water. XRD and FT-IR results affirms the cryatalinity and successful formation of the composites. The elemental composition/distribution was analysed via EDS and color mapping. The elemental oxidation state and successful charge migration in hetrostructure was confirmed by XPS findings. The catalyst's surface morphology indicates tiny MoS2 nanopetals dispersed throughout C3N5 sheets, while BET studies revealed its high surface area (34.7 m2/g). The MC catalysts were highly active in visiblelight, with an energy band gap value of 2.01 eV and a lowered recombination of charges. Because of the strong synergistic relationship (2.19) in the hybrid, excellent activity for methylene blue (MB) dye (88.9%; 0.0157 min−1) and fipronil (FIP) photodegradation (85.3%; 0.0175 min−1) with MC (3:1) catalyst under visible-light irradiation was obtained. Investigations were carried out on the effect of catalyst quantity, pH, and effectual illumination area on photoactivity. Post-photocatalytic assessment verified the high re-useable character of the catalyst with a high degradation (63% (5 mg/L MB) and 54% (600 mg/L FIP)) after five cycles. The trapping investigations demonstrated that superoxide radicals and holes were intimately enrolled in the degradation activity. Remarkable removal rates of COD (68.4%) and TOC (53.1%) demonstrate excellent photocatalytic removal of practical wastewater even without any preliminary processes. The new study, when paired with previous research, demonstrates the real-world perspective of these novel MC composites for the elimination of refractory contaminants.

Combination of MoS2 nanopetals with Ag nanoparticles decorated graphene oxide for boosting photocatalytic abatement of recalcitrant pollutants under visible light irradiation

Herein, various weight ratios (1:1, 1:3, and 3:1) of MoS2/GO composites decorated with Ag nanoparticles (named as MAG) have been prepared by microwave-assisted route. XRD and XPS investigations indicated the catalyst crystallinity and elemental oxidation states. Morphological analysis revealed presence of small MoS2 nanopetals scattered on GO sheets with Ag NPs dispersed on surface whereas BET-analysis disclosed its excellent surface area (∼88 m2/g). Optical properties of MAG catalysts revealed that they were highly visible-light active, with a bandgap of 2.15 eV and a lower charge recombination rate. Excellent efficiency was observed for TC (90.7%; 0.0186 min−1) and FIP-degradation (85.2%; 0.0177 min−1) with 4 mg MAG (3:1) catalyst at neutral pH under visible-light irradiation owing to high synergistic interaction (∼2.21) in the composite. Effects of catalyst amount, pH, and effective area of illumination on degradation were investigated. High reusable nature of the catalyst (65% (TC) and 58% (FIP) efficiency after 5 cycles) was supported by post-photocatalytic characterization studies. Photodegradation products of TC were determined via LC-MS studies. Holes and hydroxyl radicals were majorly involved in degradation process revealed by trapping studies. High COD (70.4%) and TOC (55.1%) removal rates confirm high photo-mineralization of real-wastewater without any pre-treatment. The current investigation, combined with comparative literature, illustrates real-world potential of MAG catalysts for eradication of resistant pollutants.

Hierarchical Nanocapsules of Cu-Doped MoS2@H-Substituted Graphdiyne for Magnesium Storage.

Hierarchical nanocomposites, which integrate electroactive materials into carbonaceous species, are significant in addressing the structural stability and electrical conductivity of electrode materials in post-lithium-ion batteries. Herein, a hierarchical nanocapsule that encapsulates Cu-doped MoS2 (Cu-MoS2) nanopetals with inner added skeletons in an organic-carbon-rich nanotube of hydrogen-substituted graphdiyne (HsGDY) has been developed for rechargeable magnesium batteries (RMB). Notably, both the incorporation of Cu in MoS2 and the generation of the inner added nanoboxes are developed from a dual-template of Cu-cysteine@HsGDY hybrid nanowire; the synthesis involves two morphology/composition evolutions by CuS@HsGDY intermediates both taking place sequentially in one continuous process. These Cu-doped MoS2 nanopetals with stress-release skeletons provide abundant active sites for Mg2+ storage. The microporous HsGDY enveloped with an extended π-conjugation system offers more effective electron and ion transfer channels. These advantages work together to make this nanocapsule an effective cathode material for RMB with a large reversible capacity and superior rate and cycling performance.

Silver decorated 2D nanosheets of GO and MoS2 serve as nanocatalyst for water treatment and antimicrobial applications as ascertained with molecular docking evaluation

In this work, synthesis of graphene oxide (GO) and reduced graphene oxide (rGO) was realized through a modified Hummers route. Different concentrations (5 and 10 wt%) of Ag were doped in MoS2 and rGO using a hydrothermal technique. Synthesized Ag-MoS2 and Ag-rGO were evaluated through XRD that confirmed the hexagonal structure of MoS2 along with the transformation of GO to Ag-rGO as indicated by a shift in XRD peaks while Mo–O bonding and S=O functional groups were confirmed with FTIR. Morphological information of GO and formation of MoS2 nanopetals as well as interlayer spacing were verified through FESEM and HRTEM respectively. Raman analysis was employed to probe any evidence regarding defect densities of GO. Optical properties of GO, MoS2, Ag-rGO, and Ag-MoS2 were visualized through UV–vis and PL spectroscopy. Prepared products were employed as nanocatalysts to purify industrial wastewater. Experimental results revealed that Ag-rGO and Ag-MoS2 showed 99% and 80% response in photocatalytic activity. Besides, the nanocatalyst (Ag-MoS2 and Ag-rGO) exhibited 6.05 mm inhibition zones against S. aureus gram positive (G+) and 3.05 mm for E. coli gram negative (G-) in antibacterial activity. To rationalize biocidal mechanism of Ag-doped MoS2 NPs and Ag-rGO, in silico molecular docking study was employed for two enzymes i.e. β-lactamase and D-alanine-D-alanine ligase B (ddlB) from cell wall biosynthetic pathway and enoyl-[acylcarrier-protein] reductase (FabI) from fatty acid biosynthetic pathway belonging to S. aureus. The present study provides evidence for the development of cost-effective, environment friendly and viable candidate for photocatalytic and antimicrobial applications.

Direct Z‐scheme N‐doped TiO2/MoS2 Heterojunction Photocatalyst for Photodegradation of Methylene Blue under Simulated Sunlight

AbstractThe N‐doped TiO2/MoS2 heterojunction with direct Z‐scheme was prepared by growing MoS2 flowers on the surface of N‐doped TiO2 (N‐TiO2) spheres. The results show that the N‐TiO2 sphere is composed of nanoparticles with the diameter of about 10 nm. The MoS2 flowers with the diameter of 500 nm could grow homogeneously on the surface of N‐TiO2 spheres, and the latter could prevent the accumulation of MoS2 nanopetals. The N‐TiO2/MoS2 heterojunction has a narrow band gap of 2.05 eV and high activity for degrading methylene blue (MB). The degradation rate of MB by N‐TiO2/MoS2 can reach 97.9 % under simulated sunlight, which is much higher than those of TiO2, MoS2 and N‐TiO2. Moreover, the N‐TiO2/MoS2 heterojunction shows a good stability and the degradation rate of MB keeps up to 85.9 % after being subjected to five cycles.

FeNiSx@MoS2 Heterostructure: A Bioinspired Nonprecious Electrocatalyst for the Hydrogen Evolution Reaction in Acidic and Basic Media

AbstractFeNiSx@MoS2 (INSMS) heterostructure is designed and developed to achieve a structural and functional analogue with biological enzyme active sites that catalyze hydrogen production. A two‐step synthetic method is applied to develop the heterostructure. As‐prepared INSMS integrates FeNiSx (INS) nanosheets on the surface of the MoS2 nanopetals. The electrocatalyst demonstrates robust hydrogen evolution reaction (HER) activity due to the selective decoration of INS nanosheets over MoS2, owing to their different solubility product values. Two different phases of INS nanosheets are formed in INSNS due to the topotactic transition of INS nanosheets, as confirmed by the XRD and HR‐TEM analysis. In the HER, INSMS requires overpotentials of 110 and 155 mV at 10 mA cm−2 with Tafel slope values of 34 and 93 mV dec−1 in acidic and alkaline medium, respectively. This improved electrochemical performance is generated by the modification of the electron‐hole separation at the heterostructure interface and interlinked active edge sites at the interface.

Outstanding performance of silver-decorated MoS2 nanopetals used as nanocatalyst for synthetic dye degradation

Abstract Silver (Ag) decorated MoS2 nanopetals were synthesized by adopting hydrothermal approach. MoS2 nanopetals were doped with various concentrations (2.5, 5, 7.5, 10 wt%) of Ag and characterized using different techniques. The presence of hexagonal MoS2 and an increase in crystallite size with the addition of Ag was confirmed through XRD. Molecular vibration and presence of characteristic peaks of Mo–O and S–O were verified with FTIR spectroscopy. Morphological features and formation of nanopetals were corroborated with FESEM and HR-TEM microscopy. Elemental composition and existence of dopant were confirmed with EDS. Raman analysis was employed to seek further evidence regarding defects densities and electronic band structure of MoS2. Optical properties upon conjugation with Ag were analyzed with UV–vis. and PL spectroscopy. In addition, dye degradation of bare and doped samples was tested in the presence of a reducing agent (NaBH4). These nanocatalysts show outstanding potential to remove hazardous toxins, such as synthetic dyes and tannery pollutants, from industrial effluents.

Designing of waste fruit peels extracted cellulose supported molybdenum sulfide nanostructures for photocatalytic degradation of RhB dye and industrial effluent

Waste fruit peels which are usually discarded as agricultural wastes were utilized to isolate cellulose. The varied amount of isolated cellulose was used as sustainable support with hydrothermally synthesized molybdenum sulphide (MoS2) nano-petals via in-situ approach. The phase purity of all synthesized nanostructures was confirmed by PXRD whereas different oxidation states along with the interaction of cellulose with the MoS2 were examined by XPS analysis. In order to evaluate the performance of catalyst, the photodegradation rate was calculated for RhB dye as well as industrial effluent in visible light. The upgradation in photocatalytic competence was found significant by cellulose supported MoS2 nanostructures as compared to bare MoS2 nano-petals due to slow recombination of electron hole pairs. The maximum rate was pronounced by employing the cellulose at an amount of ~500 mg as a support due to existence of an optimal point where the delay in charge recombination reaches maximum.

Controllable synthesis of MoS2/graphene low-dimensional nanocomposites and their electrical properties

In this study, a novel hydrothermal route has been developed for the synthesis of MoS2/graphene composite with controllable structures, in which ammonium molybdatetetrahydrate, as-prepared graphene oxide (GO), and thioacetamide were used as staring materials. Effects of Mo4+-to-C precursor ratios and crystalline time on the structures, components and morphologies of MoS2/graphene were investigated. MoS2/graphene samples were characterized using XRD, FESEM, HRTEM, FTIR, Raman spectroscopy, HAADF-STEM/EDS, HXPES and electrical measurements. The results show that petal-like MoS2 nanostructures with ultrathin petals (~1–10 layers) and coexistence of 1T- and 2H-MoS2 phases can be synthesized on graphene surface in a short time (~2 h). Comparison of crystallization conditions, we found that the crystallization time had a significant effect on the size of the MoS2 nanopetals. The shorter the reaction time is, the thinner the petal-like MoS2 nanoscale is. On the other hand, by adjusting the ratios of Mo4+to C (denoted as: MoS2/C (1:2), MoS2/C (3:2), MoS2/C (2.5:1) and MoS2/C (3:1)), different MoS2/graphene architectures including “sandwich-liked”, “layer–by–layer” and “anchored” can be obtained. On the basis of these results, a possible growth mechanism of MoS2nanopetals on GO was proposed. Interestingly, the as-synthesized material depicts its memristive behavior through the Volt-Ampere characteristics, suggesting a potential application in logic memory devices.

Controllable synthesis of P-doped MoS2 nanopetals decorated N-doped hollow carbon spheres towards enhanced hydrogen evolution

In order to construct the molybdenum disulfide (MoS2) hybrid nanostructure with enhanced conductivity and more active sites towards electrocatalytic hydrogen evolution reaction (HER), hierarchical P-doped MoS2 nanopetals decorated N-doped hollow carbon spheres (N-C@P-MoS2) core-shell structures were synthesized via calcination and hydrothermal methods. N-C@P-MoS2 with optimized loadings exhibited favorable HER activities with low onset overpotential (117 mV), small Tafel slopes (68 mV/dec), and fine stability compared with pure MoS2 nanosheets and all undoped samples. This is largely ascribed to the synergy of MoS2 and carbon in the rational hierarchical structures, as well as the modified electronic structure with improved conductivity, increased active sites by virtue of N and P doping. Furthermore, P-doped MoS2 nanosheets were encapsulated in carbon spheres (N-C/P-MoS2 (inside)) by controlling the dropping rate of adding MoS2 precursors. As the active sites were hampered, the N-C/P-MoS2 (inside) revealed poor HER performance compared with the core-shell counterparts. The results demonstrate that the fabrication of hierarchical MoS2/carbon composites with the synergy of structural (morphology and content) and electronic (active sites and conductivity) effects induced by various nonmetal doping pave the way for enhanced electrocatalytic HER activities.

Construction of In2Se3/MoS2 heterojunction as photoanode toward efficient photoelectrochemical water splitting

κ-In2Se3, a rarely reported phase of indium selenide, is synthesized here using a hot-injection method. The hexagonal nanoplates show photoresponses at positive bias, thus is considered as a potential material for photoanode utilization. In order to further improve the photoelectrocatalytic performance of κ-In2Se3, MoS2 nanopetals are introduced by a solution-based ultrasonic method. The In2Se3/MoS2 heterojunction exhibits a significantly higher photocurrent density and higher PEC O2 evolution amount than those of pristine In2Se3. PL test shows that the charge separation is promoted, due to numerous p-n junctions formed at the interfaces of In2Se3/MoS2. This led to more efficient utilization of photogenerated electron-hole pairs. Moreover, the charge transfer resistance is greatly reduced by the cooperative interaction of the two materials.

Metallic-Phase MoS2 Nanopetals with Enhanced Electrocatalytic Activity for Hydrogen Evolution

MoS2 shows a great promise as a low-cost and highly active alternative to platinum-based catalysts for electrochemical hydrogen production from water. The activity of MoS2 is believed from the edge, defect sites, and the basal plane of metallic phase (M-MoS2). Here we report on a facile hydrothermal method for the preparation of MoS2 nanopetals that are in metallic phase and have abundant edges. The amount of sulfur precursors are found to play a critical role on the formation of MoS2 nanopetals. The MoS2 nanopetals exhibit remarkable electrocatalytic activities for the hydrogen evolution reaction (HER), with a low overpotential of 210 mV at the current density of 10 mA cm–2 and a Tafel slope of 44 mV per decade. The MoS2 nanopetals also display very good durability, with a very small negative shift of 11 mV at the current density of 10 mA cm–2, and negligible shift at the current density of 50 mA cm–2 after 2000 cycles. Our facile preparation method and high electrocatalytic activity of MoS2 nanopetals f...

Use of lactic acid modified MoS2 nanopetals to improve photocatalytic degradation of organic pollutants

Transition metal dichalcogenide-based molybdenum disulfide (MoS2) are currently gaining considerable attention due to their prospective technological applications. Herein, we report a facile and simple one-step preparation of self-assembled two-dimensional MoS2 nanopetals modified with lactic acid (LA@MoS2). An investigation of the properties of the synthesized LA@MoS2 nanopetals under different conditions reveals that the weight percentage of lactic acid (LA) significantly influences the structural purity, crystalline quality, and morphology of the products, and the appropriate concentration of LA is the determining factor in the synthesis. Photocatalytic activity of LA@MoS2 nanopetals for organic dye decolorization is examined using crystal violet (CV) and methyl orange (MO). The results showed that LA molecules cover the MoS2 with C–S bonds, which significantly enhance photocatalytic decolorization of CV and MO pollutants under simulated solar light irradiation. The LA@MoS2 demonstrated excellent photocatalytic performance compared to bulk MoS2. Furthermore, electrochemical studies reveal fast electron and hole pathways for the reduction of pollutant molecules in aqueous solution. These results indicate that LA@MoS2 is a good photocatalyst because of the desirable active species in the modified catalyst.

Controlled growth of MoS2 nanopetals on the silicon nanowire array using the chemical vapor deposition method

In order to get a physical/chemical insight into the formation of nanoscale semiconductor heterojunctions, MoS2 flakes are deposited on the silicon nanowire (SiNW) array by chemical vapor deposition (CVD). In this study, H2O2 treatment provides a favorable place where the formation of SiO bonds on the SiNW surfaces that play important roles (i.e., the nucleation centers, catalyst control centers or “seeds”) can dominate the growth of MoS2 on the SiNWs. Using this configuration, the effect of a change in the S/MoO3 mass ratio (MS/MMoO3) on the surface morphology of MoS2 is studied. It is shown that an increase in the value of MS/MMoO3 leads to the increased nucleation rate, increasing the size of MoS2 nanopetals. This study provides valuable scientific information for directly CVD-grown edge-oriented MoS2/SiNWs heterojunctions for various nanoscale applications, including hydrogen evolution reaction and electronic and optoelectronic devices.

Enhanced hydrogen evolution performance of ultra thin nanoslice/nanopetal structured XS2 (X = W, Mo): From experiment to theory

The production of H2 through water splitting to make the reaction process economical and friendly has attracted a lot attention. In this work, we synthesized the novel well-defined nanostructured WS2/MoS2 composite for using as the electrocatalyst of hydrogen evolution. The final obtained nanoslice/nanopetal nanostructured WS2/MoS2 composite possessed massive active sites that originated from its well-defined hierarchical structure with densely stacked MoS2 nanopetals. The synthesized composite exhibited significantly enhanced hydrogen evolution reaction (HER) activity and clearly superior to the pristine MoS2/WS2. With the purpose to give a theoretical explanation of the corresponding enhancement mechanism, the first-principles investigation based on the density functional theory was further employed to survey the electronic properties of different structures. Charge density difference and Bader charge analyses revealed that electrons could directional transfer from WS2 to MoS2 and provided an “electron-rich” environment, which was beneficial to the improvement of HER efficiency. These analytical methods will necessarily offer new angles to explain the enhancement mechanism of HER processes regarding the interaction between WS2 and MoS2, which can accurately elucidate the reason why composite structure exhibits a better HER performance based on the experimental results.

Controlled growth of MoS2 nanopetals and their hydrogen evolution performance

From horizontal to vertical growth, dense edge-oriented MoS2 nanopetals have been synthesized via an APCVD method through the spiral growth mechanism.

Synthesis of MoS2 nano-petal forest supported on carbon nanotubes for enhanced field emission performance

We report the fabrication of a three-dimensional forest of highly crystalline two-dimensional (2D) molybdenum disulfide (MoS2) nano-petals encapsulating vertically aligned carbon nanotubes (CNT) in a core-shell configuration. Growth was conducted via magnetron sputtering at room temperature and it was found that the nano-petal morphology was formed only when a critical threshold in sputter deposition time was reached. Below this threshold, an amorphous tubular structure composed of mainly molybdenum oxides dominates instead. The presence of the MoS2 nano-petals was shown to impart photoluminescence to the CNTs, in addition to significantly enhancing their electron emission properties, where the turn-on field was lowered from 2.50 Vμm−1 for pristine CNTs to 0.80 Vμm−1 for MoS2-CNT heterostructures fabricated at 30 min sputter deposition time. Photoluminescence was detected at wavelengths of approximately 684 nm and 615 nm, with the band at 684 nm gradually blue-shifting as sputter time was increased. These results demonstrate that it is possible to synthesize 2D MoS2 layers without the need for chemical routes and high growth temperatures.