Doped Molybdenum Disulfide Research Articles

Targeting pharmaceutical phenol; a thorough analysis of manganese doped molybdenum disulfide (MoS2) catalyst, augment by MB dye assesment

The innovative materials for the wastewater treatment have gained significant attention for the utilization to control environmental remediation. In the context, this study explores the fabrication and applications of Manganese doped molybdenum disulfide (Mn–MoS2) with (0 %, 2 %, 3 %, 4 %, 5 %) concentrations by hydrothermal approach. This article highlights the successful incorporation of well-matched manganese (Mn+2) in base materials and evaluates their powers for the degradation of pharmaceutical phenol and methyl blue (MB) dye. The prepared nanostructures delve into various characterizations to study their structural, morphological, elemental, optical and electronic properties. The X-ray Diffraction (XRD) and Fourier-transform infrared Spectroscopy (FTIR) shed lights insight the structures. The Energy Dispersive X-ray Spectroscopy (EDX) and Scanning Electron Microscope (SEM) are used to showcase the imagery of elemental and morphological properties. The Zeta Potential examines the conductivity while Brunauer-Emmett-Teller (BET) is carried to determine the specific surface area. Additionally, Ultraviolet Visible Spectroscopy (UV) and Photoluminescence Spectroscopy (PL) elucidate the optical properties of the synthesized materials. The synergistic interplay between the dopant and host material MoS2 resulted to effective degradation, integrating the potential of successful environmental remediation agent of Mn–MoS2.

Improvement in efficiency of MoS2 nanoflower based ethylene gas sensor on transition metal doping: An experimental and theoretical investigation

There is an immense need for inexpensive, accurate, and repeatable ethylene sensors for post-harvest management. This paper presents resistive-type sensors based on transition metal (Ni, Fe, Co) doped molybdenum disulfide (MoS2) nanoflowers synthesized via simple hydrothermal route. A comparative study of sensing properties of pristine MoS2 and doped (Ni, Fe, Co)-MoS2 was performed in natural ambient conditions. The results reveal that Ni-doped MoS2 shows the optimized result in sensitivity as well as lower detection limit, compared to other three materials. Density functional theory (DFT) studies were carried out to evaluate interaction of ethylene molecules with MoS2 and doped MoS2. The sensing mechanism for all the materials was investigated in terms of adsorption energy, density of states (DOS), and charge transfer. The calculated results indicate large adsorption energy and higher charge transfer in the case of Ni-doped MoS2 supporting the experimental findings.

Molecular modeling and simulation of transition metal-doped molybdenum disulfide biomarkers in exhaled gases for early detection of lung cancer.

The presence of volatile organic compounds (VOCs) in the exhaled breath of lung cancer patients is the only available source for detecting the disease at its initial stage. Exhaled breath analysis depends purely on the performance of the biosensors. The interaction between VOCs and pristine MoS2 is repulsive in nature. Therefore, modifying MoS2 via surficial adsorption of the transition metal nickel is of prime importance. The surficial interaction of six VOCs with Ni-doped MoS2 led to substantial variations in the structural and optoelectronic properties compared to those of the pristine monolayer. The remarkable improvement in the conductivity, thermostability, good sensing response, and recovery time of the sensor exposed to six VOCs revealed that a Ni-doped MoS2 exhibits impressive properties for the detection of exhaled gases. Different temperatures have a significant impact on the recovery time. Humidity has no effect on the detection of exhaled gases upon exposure to VOCs. The obtained results may encourage the use of exhaled breath sensors by experimentalists and oncologists to enable potential advancements in lung cancer detection. The surface adsorption of transition metal and its interaction with volatile organic compounds on a MoS2 surface was studied by using Spanish Initiative for Electronic Simulations with Thousands of Atoms (SIESTA). The pseudopotentials used in the SIESTA calculations are norm-conserving in their fully nonlocal forms. The atomic orbitals with finite support were used as a basis set, allowing unlimited multiple-zeta and angular momenta, polarization, and off-site orbitals. These basis sets are the key for calculating the Hamiltonian and overlap matrices in O(N) operations. The present hybrid density functional theory (DFT) is a combination of PW92 and RPBE methods. Additionally, the DFT+U approach was employed to accurately ascertain the coulombic repulsion in the transition elements.

Performance of molybdenum-based carbon doped molybdenum disulfide electrode for sulfur oxidation reaction

Performance of molybdenum-based carbon doped molybdenum disulfide electrode for sulfur oxidation reaction

Transversal nanochannel-enabled MXene laminated membranes for superior oil-water separation: A fluid mosaic cytomembrane inspired approach

Transition metal carbide and nitride materials (MXenes) have been greatly appreciated for their facilely exfoliated and hydrophilic two-dimensional (2D) layered structure to fabricate laminated membranes for oil separation. However, the denser slits and longer interlayer transport of traditional MXene membranes usually result in the poor permeability and antifouling performance. Herein, a novel approach was developed by synthesizing ultra-thin MXene and ferroferric oxide doped molybdenum disulfide (FM) and subsequently embedding FM into MXene laminates. This method yielded additional transversal nanochannels that enable lateral transport in a manner akin to that of a mosaic transport protein. Additionally, the incorporation of FM resulted in the creation of extremely irregular surfaces that form extensive membrane structures, reminiscent of tightly packed phospholipid bilayers. The incorporation of flower-like FM composites with MXene laminates endowed the resultant membrane with improved interface hydrophilicity, intensive surface roughness and enhanced permeability. These effects synergistically contributed to an exceptionally high pure water flux of the resultant membrane (3.12 × 104 L m−2 h−1), surpassing that of the control membrane (6.15 × 103 L m−2 h−1) without FM by over 5-fold. Furthermore, the optimum membrane exhibited enhanced permeance to oil mixtures (3.75 × 103 L m−2 h−1) and emulsions (4.25 × 102 L m−2 h−1), with separation of over 99% remaining. Impressively, the permeability of severely fouled membranes could be restored by 99% under visible light, highlighting the admirable photocatalytic self-cleaning ability enabled by MXene and FM. The underlying mechanisms that account for the superior antifouling performance and self-cleaning ability of the laminated membrane were also elucidated by the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory. The facile fabrication strategy employing transversal transport laminates provides a remarkable approach for water purification and other fluidic separation applications.

Fabrication of La‐Doped MoS2 Nanosheets with Tuned Bandgap for Dye Degradation and Antimicrobial Activities, Experimental and Computational Investigations

AbstractThe development of efficient catalysts with a large number of active sites, tunable bandgap, and large surface area has been very challenging. In addition, a significant bottleneck in the application of catalysts for water treatment is their dissolution under extreme conditions, such as highly acidic or highly alkaline conditions that lead to poor application of the reported materials in real‐world applications. In this study, the lanthanum (La)‐doped molybdenum disulfide (MoS2) nanosheets are reported for efficient breakdown of toxic pollutants from wastewater under a wide pH range from strongly alkaline to strongly acidic solutions. The La‐MoS2 nanosheets (NSs) are prepared by a facile hydrothermal approach using a two‐step methodology. A redshift is observed upon La doping, indicating that the bandgap is lowered after La doping in MoS2. The changes in bandgap and electronic structure are further investigated using the density functional theory (DFT), which reveal that doping of La introduces new states within the bandgap region, allowing for further induced energy transitions. The La‐MoS2, having a doping concentration of 2%, exhibits the highest catalytic activity against methylene blue (MB) in neutral, acidic, and alkaline solutions, as well as substantial inhibitory activity for bacterial strains such as Escherichia coli (E. coli). In summary, the modified catalyst provides a pathway to design highly efficient catalysts for all pH range water treatment as well as good activity against microbes.

Phosphorus doped molybdenum disulfide regulated by sodium chloride for advanced supercapacitor electrodes.

As a pseudocapacitor electrode material, molybdenum disulfide (MoS2) usually shows inferior capacity, rate capability and cyclability. Structural regulation and heteroatom doping are the available methods to ameliorate the electrochemical properties of MoS2. Herein, phosphorus doped molybdenum disulfide regulated by sodium chloride (SP-MoS2) is successfully synthesized using phosphomolybdate acid as a molybdenum source and an in situ dopant and sodium chloride (NaCl) as a structural regulator. Under the structural regulation of NaCl, the SP-MoS2 nanosheets exhibit an interweaved architecture with a large interlayer spacing of 0.68 nm. Owing to the in situ P doping and large specific surface area (21.0 m2 g-1), the SP-MoS2 electrode possesses a maximum capacity of 564.8 F g-1 at 1 A g-1 and retains 56.3% of the original capacity at 20 A g-1. Density functional theory (DFT) calculations indicate that SP-MoS2 displays a high K+ average adsorption energy of -3.636 eV. In addition, the fabricated SP-MoS2//AC asymmetric supercapacitor device displays an energy density of 22.8 W h kg-1 at 759 W kg-1.

In-Situ Generation of Nitrogen-Doped MoS2 Quantum Dots Using Laser Ablation in Cryogenic Medium for Hydrogen Evolution Reaction

Here, nitrogen doped molybdenum disulfide quantum dots (N-MoS2 QDs) are fabricated by making use of the pulsed laser ablation (PLA) process in liquid nitrogen (LN2) as a dopant agent. In fact, LN2 contributes the rapid condensation of the plasma plume to form MoS2 QDs, optimizing the conditions for the synthesis of N-doped MoS2 with p-type property. The structural/optical features of the synthesized products are studied using transmission electron microscopy (TEM), absorption spectroscopy, photoluminescence (PL) spectroscopy techniques, and X-ray photoelectron spectroscopy (XPS). The TEM image shows the creation of MoS2 QDs with 5.5 nm average size. UV-vis and PL spectroscopy confirm the formation of N-MoS2 QDs according to the dominant peaks. The Tuck plot gives a direct band-gap of 4.34 eV for MoS2 QDs. Furthermore, XPS spectroscopy reveals Mo-N bonding, indicating nitrogen doping as evidence of p-type MoS2 QDs. Thus, PLA provides a single-stage way to the clean and green synthesis of the MoS2 QDs suspension without a need for high vacuum devices and additional chemical components. Regarding the pristine MoS2, the N-MoS2 QDs benefit from a low overpotential of −0.35 V at −10 mA/cm2 per µg alongside a low Tafel slope of 300 mV/dec. Subsequently, the lower Rct value of N-MoS2 QDs verifies the enhancement of the charge transfer kinetics mainly due to the elevated electronic conductivity. Furthermore, the quasi-rectangular cyclic voltammetry (CV) as well as the larger current window demonstrate a notable electrocatalytic activity. The former is based on the enhanced active sites in favor of N-MoS2 QDs against other samples of interest. Thereby, it is discovered that the N-doped MoS2 QD acts as an effective catalyst to notably improve the performance of the hydrogen evolution reaction (HER).

Amorphous cobalt doped MoS2 as a bifunctional electrocatalyst

• The amorphous cobalt (Co)-doped molybdenum disulfide (MoS 2 ) was firstly prepared. • The Co-doped MoS 2 shows outstanding electrocatalytic performances. • The Co-doped MoS 2 has potential as a bifunctional electrocatalyst. It is important to develop non-noble metal bifunctional electrocatalysts in the zinc-air battery. Herein, we doped different contents of cobalt to form Co-doped MoS 2 by one-pot hydrothermal method, the so-obtained Co 0.05 -MoS 2 is proved to be an amorphous structure, showing outstanding electrocatalytic performances that the half-wave potential is 0.80 V and the OER potential is 1.54 V at 10 mA cm −2 , and the (voltage gap) Δ E value is as low as 0.74 V, which are much superior to the commercial Pt/C + RuO 2 electrocatalyst. Moreover, the good stability of Co 0.05 -MoS 2 makes it have the potential to be applied in the zinc-air battery.

Magnetically Doped Molybdenum Disulfide Layers for Enhanced Carbon Dioxide Capture.

Carbon capture and storage (CCS) technologies have the potential for reducing greenhouse gas emissions and creating clean energy solutions. One of the major aspects of the CCS technology is designing energy-efficient adsorbent materials for carbon dioxide capture. In this research, using a combination of first-principles theory, synthesis, and property measurements, we explore the CO2 gas adsorption capacity of MoS2 sheets via doping with iron, cobalt, and nickel. We show that substitutional dopants act as active sites for CO2 adsorption. The adsorption performance is determined to be dependent on the type of dopant species as well as its concentration. Nickel-doped MoS2 is found to be the best adsorbent for carbon capture with a relatively high gas adsorption capacity compared to pure MoS2 and iron- and cobalt-doped MoS2. Specifically, Brunauer-Emmett-Teller (BET) measurements show that 8 atom % Ni-MoS2 has the highest surface area (51 m2/g), indicating the highest CO2 uptake relative to the other concentrations and other dopants. Furthermore, we report that doping could lead to different magnetic solutions with changing electronic structures where narrow band gaps and the semimetallic tendency of the substrate are observed and can have an influence on the CO2 adsorption ability of MoS2. Our results provide a key strategy to the characteristic tendencies for designing highly active and optimized MoS2-based adsorbent materials utilizing the least volume of catalysts for CO2 capture and conversion.

Vanadium defect-engineering in molybdenum disulfide for electrochemical nitrate reduction

In this work, vanadium doped molybdenum disulfide (V–MoS2) electrocatalysts are successfully prepared by using vanadium defect-engineering for electrochemical nitrate reduction reaction (NITRR), which has significantly improved NITRR activity.

Modulation of electronic and thermal proprieties of TaMoS[formula omitted] by controlling the repulsive interaction between Ta dopant atoms

We theoretically study the electronic and the thermal characteristics of Tantalum, Ta, doped Molybdenum disulfide, MoS2, using density functional theory. It has been shown that the MoS2 monolayer is not a good material for thermoelectric devices due to its relatively large band gap. We find that a Ta doped MoS2 forming a TaMoS2 monolayer can be useful for thermoelectric devices. The particular attention of this work is paid to the interaction effect between the Ta atoms in the MoS2 structure. We find that the interaction type is repulsive. It introduces an asymmetry in the density of states, DOS, reducing the band gap. In the presence of a strong repulsive interaction of Ta–Ta atoms, new states in the DOS around the Fermi energy are found leading to a reduction of the band gap. Consequently, a high Seebeck coefficient and figure of merit are seen over a wide range of energy around the Fermi energy. In contrast, a small reduction of the band gap and a vanishing degeneracy of the valence and the conduction bands are observed for the case of a weak Ta–Ta repulsive interaction leading to less promising thermoelectric properties.

The study of oxygen reduction reaction on Ge‐doped MoS 2 monolayer based on first principle

Rational design of electrocatalyst for air cathode with high oxygen reduction reaction (ORR) performance is highly demanded. However, current low performance of electrocatalyst remains a big challenge. Herein, the possibility of germanium (Ge)-doped molybdenum disulfide (MoS2) monolayer as a novel electrocatalyst for ORR in alkaline solution was studied based on first principle calculation. The results indicate that oxygen is strongly adsorbed on the surface of Ge-doped MoS2 monolayer. Moreover, a high barrier should be overcome during H2O molecular dissociation and the barrier of dissociation decreases with the number of doped Ge atoms increasing. Based on the calculation of transition state and Gibbs free energy, the triple Ge atoms-doped MoS2 monolayer shows the best activity toward ORR with the lowest rate-determine step barrier of 0.23 eV. Our study may provide a meaningful method for the design of novel MoS2-based electrocatalyst for ORR.

Tailoring the structure and energy level over transition-metal doped MoS2 towards enhancing 4-nitrophenol reduction reaction

Exploring high-efficiency, robust and cost-effective catalysts for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) is greatly desirable. Herein, a series of transition-metal doped MoS2 (M-MoS2, M = Mn, Fe, Co, Ni, Cu, Zn) with expanded interlayer spacing are fabricated by one-step solvothermal strategy. Notably, nickel doped molybdenum disulfide (Ni-MoS2) is found to exhibit prominent catalytic activity with an apparent rate constant (K) of 1.09 min-1 and excellent stability over six continuous runs of recycling experiments. The results demonstrate that the expanded interlayer spacing (0.94 nm) can increase the active sites of reactant absorption, and Ni dopants can lower the energy level (d‐band center) to facilitate the desorption of H. Thus, the catalytic activity of Ni-MoS2 is enhanced by synergistically structural and energy level modulation. This study offers an effective strategy to design transition metal sulfides with higher catalytic reactivity for the environment-related catalysis processes.

Structural, morphological, optical, and photocatalytic properties of Ag-doped MoS2 nanoparticles

Nanoparticles of Ag doped molybdenum disulfide (Ag–MoS2) were synthesized by hydrothermal process. The structural, morphological, and optical characterisics of these nanoparticles were characterized by scanning electron microscopy (SEM), Raman spectroscopy, and photoluminescence spectroscopy (PL), respectively. Raman spectra confirmed the formation of MoS2 and Ag-doped MoS2 nanoparticles. SEM images indicated that sheet-like structure is prepared in undoped MoS2, while Ag–MoS2 has a particle-like structure. PL peaks are observed at 600 nm (2.06 eV), 610 nm (2.03 eV), 700 nm (1.77 eV), 725 nm (1.71 eV), and 730 nm (1.69 eV) for pure, 1% and 2% Ag– MoS2. When the doping amount of Ag is increased further (i.e., to 3% Ag-doped MoS2), new peaks at 636 nm (1.9 eV) and 663 nm (1.87 eV) are observed due to an increase in structural defects. The photocatalytic activity (PCA) of undoped and Ag–MoS2 is estimated by monitoring the degradation of rhodamine blue (RhB) and methylene blue (MB) dyes. The PCA of Ag–MoS2 samples are greater than that of undoped MoS2 when irradiated with visible light, which is attributed to increased electron–hole pair separation.

Synergistic effect of Bi-doped exfoliated MoS2 nanosheets on their bactericidal and dye degradation potential.

Nanosheets incorporated with biological reducing agents are widely used to minimize the toxic effects of chemicals. Biologically amalgamated metal oxide nanomaterials have crucial importance in nanotechnology. In this study, bare and bismuth (Bi)-doped molybdenum disulfide (MoS2) nanosheets were synthesized via a hydrothermal method. Different Bi weight ratios of 2.5, 5, 7.5 and 10% were incorporated in a fixed amount of MoS2 to evaluate its catalytic and antimicrobial activities. Doped nanosheets were characterized using XRD, FTIR and UV-vis spectroscopy, FESEM, HRTEM, Raman, PL, DSC/TGA, EDX, XRF and XPS analysis. The XRD spectra confirmed that the doped nanosheets exhibit a hexagonal structure and their crystallite size increases gradually upon doping. The morphology and interlayer d-spacing of doped MoS2 were determined by FESEM and HRTEM. The presence of functional groups in the doped nanosheets was confirmed using FTIR, PL and Raman analysis. The absorption intensity increased and the corresponding measured band gap energy decreased with doping. The thermal stability and weight loss behaviour of the prepared samples were studied using DSC/TGA. The doped MoS2 nanosheets showed a higher catalytic potential compared to undoped MoS2. The doped Bi nanosheets exhibited higher antimicrobial activity against Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) at different concentrations of Bi (0.075 and 0.1), showing a tendency to counter the emerging drug resistance against pathogenic bacterial diseases. Consequently, significant inhibition zones were recorded against (MDR) S. aureus ranging from 2.25 to 3.3 mm and 3.25 to 5.05 mm at low and high concentrations of doped-Bi nanosheets and against Gram-negative E. coli ranging from 1 to 1.45 mm at high concentrations. In conclusion, the Bi-doped MoS2 nanocomposite has exhibited significant potential for use in industrial dye degradation applications. Its antibacterial properties can also mitigate health risks associated with the presence of several well-known pathogens in the environment.

Adsorption and Diffusion of Lithium in Doped Molybdenum Disulfide Single-Layer with Metal Substituted Sulfur Atom

Considering the S-vacancy defect in single-layer MoS2, the metal doped including Fe-, Co-, Cu-, Zn-, doped specimens in MoS2 single-layer and their effect of the adsorption and diffusion of Li on the MoS2 single-layer were investigated by Density Functional Theory (DFT). Under Mo-rich condition, the Fe-, Co-, Cu-, Zn-doped specimens by substitution of S atom have smaller formation energy than those under S-rich condition. For doped MoS2 single-layer, lithium donates electron to doped specimens, making the band level of the doped specimens downward into the valence band and the Fermi energy level further upward. The Li ion has positive charge, the ion adsorptive property was enhanced because of strong coulomb interaction. These are confirmed by the large adsorption energies (-1.11 ~ -0.44 eV). The diffusion energy barriers except for the path closest doped specimens by substitution of S atom are ~ 0.25, which are similar to that of pristine one. Above all, the metal doped by substitution of S atom MoS2 single-layer are promising anode materials of LIBs.

Strain Effect on the Magnetism of N‐Doped Molybdenum Disulfide

The strain effect on the magnetic properties of nitrogen doped molybdenum disulfide has been investigated by first‐principles calculations. Two different configurations are studied: single nitrogen doping structure (NMo16S31) and dense nitrogen doping structure (NMo4S7). The first structure is a magnetic semiconductor, while the second structure is a nonmagnetic metal. Interestingly, the magnetism of both configurations can be modulated by biaxial tensile strain. Half‐metallic behavior can also be realized in both configurations under strain. The strain‐induced magnetism and extraordinary spin ordering can be attributed to the doping of nitrogen atoms, the instability of molybdenum atoms under strain, and the antiferromagnetic Mo–Mo interaction. Our calculations suggest nitrogen doped molybdenum disulfide may be used in low‐dimensional spintronic devices.

Engineering MoS2 Basal Planes for Hydrogen Evolution via Synergistic Ruthenium Doping and Nanocarbon Hybridization.

Promoting the intrinsic activity and accessibility of basal plane sites in 2D layered metal dichalcogenides is desirable to optimize their catalytic performance for energy conversion and storage. Herein, a core/shell structured hybrid catalyst, which features few‐layered ruthenium (Ru)‐doped molybdenum disulfide (MoS2) nanosheets closely sheathing around multiwalled carbon nanotube (CNT), for highly efficient hydrogen evolution reaction (HER) is reported. With 5 at% (atomic percent) Ru substituting for Mo in MoS2, Ru‐MoS2/CNT achieves the optimum HER activity, which displays a small overpotential of 50 mV at −10 mA cm−2 and a low Tafel slope of 62 mV dec−1 in 1 m KOH. Theoretical simulations reveal that Ru substituting for Mo in coordination with six S atoms is thermodynamically stable, and the in‐plane S atoms neighboring Ru dopants represent new active centers for facilitating water adsorption, dissociation, and hydrogen adsorption/desorption. This work provides a multiscale structural and electronic engineering strategy for synergistically enhancing the HER activity of transition metal dichalcogenides.

Tuning orbital orientation endows molybdenum disulfide with exceptional alkaline hydrogen evolution capability

Molybdenum disulfide is naturally inert for alkaline hydrogen evolution catalysis, due to its unfavorable water adsorption and dissociation feature originated from the unsuitable orbital orientation. Herein, we successfully endow molybdenum disulfide with exceptional alkaline hydrogen evolution capability by carbon-induced orbital modulation. The prepared carbon doped molybdenum disulfide displays an unprecedented overpotential of 45 mV at 10 mA cm−2, which is substantially lower than 228 mV of the molybdenum disulfide and also represents the best alkaline hydrogen evolution catalytic activity among the ever-reported molybdenum disulfide catalysts. Fine structural analysis indicates the electronic and coordination structures of molybdenum disulfide have been significantly changed with carbon incorporation. Moreover, theoretical calculation further reveals carbon doping could create empty 2p orbitals perpendicular to the basal plane, enabling energetically favorable water adsorption and dissociation. The concept of orbital modulation could offer a unique approach for the rational design of hydrogen evolution catalysts and beyond.