Molybdenum Disulfide Catalyst Research Articles

Ruthenium atoms anchored on oxygen-modified molybdenum disulfide with strong interfacial coupling as efficient and stable catalysts for lithium–oxygen batteries

Rechargeable non-aqueous lithium-oxygen batteries (LOBs) have garnered increasing attention owing to their high theoretical energy density. However, their slow cathodic kinetics hinder efficient battery reactions. Nanoscale catalysts can effectively enhance electrocatalytic activity and atomic utilization efficiency. However, the agglomeration of nanoscale catalysts (such as cluster and single atoms) during continuous discharge/charge cycles leads to decreased electrochemical performance and poor cyclic stability. Herein, the ruthenium (Ru) atomic sites anchored on an O-doped molybdenum disulfide (O-MoS2) catalyst (designated as Ru/O-MoS2) was fabricated using a facile impregnation and calcination method. Strong Ru-O coupling between Ru atoms and the O-MoS2 substrate optimizes the localized electronic structure, resulting in improved electrochemical performance and enhanced resistance to Ostwald ripening. When employed as a cathode catalyst for LOBs, Ru/O-MoS2 catalyst exhibits a high reversible specific capacity (18700.5 (±59.8) mAh g−1), good rate capability, and enhanced long-term stability (115 cycles, 1200 h). This study encourages facile and efficient strategies for the development of effective and stable electrocatalysts for use in LOBs.

Preparation of iron selenide decorated 1T/2H molybdenum disulfide catalysts for peroxymonosulfate activation: Effect of phase transition

The sulfate radical-based advanced oxidation process is recognized as an effective approach for acetaminophen (ACT) degradation. Modification of MoS2 through phase engineering can contribute to enhancing peroxymonosulfate (PMS) activation performance. In this work, we decorated MoS2 with FeSe2, aiming to alter the 1T/2H phase ratio of MoS2. Experiments and calculations suggested that the incorporation of FeSe2 increases the activation pathway through the Fe(III)/Fe(II) cycle and prompts a phase transition from 2H to 1T, providing active sites and boosting charge transfer between FeSe2 and MoS2. The optimum catalyst (FeSe2@MoS2-10) showed high efficiency in PMS activation, achieving complete removal of ACT within 20 min. The pseudo-first-order rate constant (kapp) on this catalyst is 17.7 times higher than that of the MoS2/PMS system. This study provides a new direction for promoting phase transition and improving the catalytic reactivity of MoS2-based catalysts, expanding their potential applications in pharmaceutical wastewater treatment.

Highly Sustainable h-BN Encapsulated MoS2 Hydrogen Evolution Catalysts.

Despite the importance of the stability of the 2D catalysts in harsh electrolyte solutions, most studies have focused on improving the catalytic performance of molybdenum disulfide (MoS2) catalysts rather than the sustainability of hydrogen evolution. In previous studies, the vulnerability of MoS2 crystals is reported that the moisture and oxygen molecules can cause the oxidation of MoS2 crystals, accelerating the degradation of crystal structure. Therefore, optimization of catalytic stability is crucial for approaching practical applications in 2D catalysts. Here, it is proposed that monolayered MoS2 catalysts passivated with an atomically thin hexagonal boron nitride (h-BN) layer can effectively sustain hydrogen evolution reaction (HER) and demonstrate the ultra-high current density (500mAcm⁻2 over 11 h) and super stable (64 h at 150mAcm⁻2) catalytic performance. It is further confirmed with density functional theory (DFT) calculations that the atomically thin h-BN layer effectively prevents direct adsorption of water/acid molecules while allowing the protons to be adsorbed/penetrated. The selective penetration of protons and prevention of crystal structure degradation lead to maintained catalytic activity and maximized catalytic stability in the h-BN covered MoS2 catalysts. These findings propose a promising opportunity for approaching the practical application of 2D MoS2 catalysts having long-term stability at high-current operation.

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.

Molybdenum disulfide catalyzed co-hydrogenation of coal tar and coking residue

Co-hydrogenation of coking residual (CR) and coal tar (CT) is an important idea to expand the field of petroleum processing technology. A low crystallinity molybdenum disulfide catalyst was synthesized by the two-step hydrothermal method and applied to CT/CR co-hydrogenation. The co-hydrogenation can increase the yield of light fuel while decreasing gas, and coke yields. In addition, the co-hydrogenation will result in a significant increase of polycyclic aromatic hydrocarbons (PAHs), a significant decrease of alkanes and monocyclic aromatic hydrocarbons (MAH), and a favorable naphthalene generation in the products. This provides a new idea to produce chemicals from poor-quality oils.

Effect of Ni/Mo on the preparation of non-loaded NiMoSx catalysts and the hydrogenation performance of coal tar

Efficient and clean utilization of coal tar is one of the key technologies for efficient and clean utilization of coal. Molybdenum disulfide has been favored for its superior catalytic hydrogenation of poor-quality oil. Molybdenum disulfide catalysts doped with different contents of nickel were synthesized by a two-step method. By SEM, XRD, Raman analyses, and other analyses. non-loaded NiMoSx-0.1 catalysts with larger lateral dimensions, fewer layers, and the appearance of specific active sites at both Basal and Edge positions were synthesized when Ni/Mo = 0.1 compared to undoped molybdenum disulfide. When Ni/Mo is continuously increased, the conversion of the intermediate MoS4-xOx is severely affected, which decreases the amount of MoS2 generated and increases the number of MoS2 layers and transverse dimensions. NiMoSx-0.1 promotes the conversion of CA to CN and enhances the hydrogenation and cracking of coal tar. The total gasoline and diesel content of the hydrotreating product was increased by 13.6 % with no coke production, in addition to the viscosity, density, and average molecular mass decreasing by 90 %, 5 %, and 33 %, respectively.

Edge-rich molybdenum disulfide tailors carbon-chain growth for selective hydrogenation of carbon monoxide to higher alcohols

Selective hydrogenation of carbon monoxide (CO) to higher alcohols (C2+OH) is a promising non-petroleum route for producing high-value chemicals, in which precise regulations of both C-O cleavage and C-C coupling are highly essential but remain great challenges. Herein, we report that highly selective CO hydrogenation to C2-4OH is achieved over a potassium-modified edge-rich molybdenum disulfide (MoS2) catalyst, which delivers a high CO conversion of 17% with a superior C2-4OH selectivity of 45.2% in hydrogenated products at 240 °C and 50 bar, outperforming previously reported non-noble metal-based catalysts under similar conditions. By regulating the relative abundance of edge to basal plane, C2-4OH to methanol selectivity ratio can be overturned from 0.4 to 2.2. Mechanistic studies reveal that sulfur vacancies at MoS2 edges boost carbon-chain growth by facilitating not only C-O cleavage but also C-C coupling, while potassium promotes the desorption of alcohols via electrostatic interaction with hydroxyls, thereby enabling preferential formation of C2-4OH.

Novel magnetic molybdenum disulfide catalyst and its application in hydrocracking reaction

Novel magnetic molybdenum disulfide catalyst and its application in hydrocracking reaction

Boosting CO2 Hydrogenation to Formate over Edge-Sulfur Vacancies of Molybdenum Disulfide.

Synthesis of formate from hydrogenation of carbon dioxide (CO2 ) is an atom-economic reaction but is confronted with challenges in developing high-performance non-precious metal catalysts for application of the process. Herein, we report a highly durable edge-rich molybdenum disulfide (MoS2 ) catalyst for CO2 hydrogenation to formate at 200 °C, which delivers a high selectivity of over 99 % with a superior turnover frequency of 780.7 h-1 surpassing those of previously reported non-precious metal catalysts. Multiple experimental characterization techniques combined with theoretical calculations reveal that sulfur vacancies at MoS2 edges are the active sites and the selective production of formate is enabled via a completely new water-mediated hydrogenation mechanism, in which surface OH* and H* species in dynamic equilibrium with water serve as moderate hydrogenating agents for CO2 with residual O* reduced by hydrogen. This study provides a new route for developing low-cost high-performance catalysts for CO2 hydrogenation to formate.

Boosting CO2 Hydrogenation to Formate over Edge‐Sulfur Vacancies of Molybdenum Disulfide

AbstractSynthesis of formate from hydrogenation of carbon dioxide (CO2) is an atom‐economic reaction but is confronted with challenges in developing high‐performance non‐precious metal catalysts for application of the process. Herein, we report a highly durable edge‐rich molybdenum disulfide (MoS2) catalyst for CO2 hydrogenation to formate at 200 °C, which delivers a high selectivity of over 99 % with a superior turnover frequency of 780.7 h−1 surpassing those of previously reported non‐precious metal catalysts. Multiple experimental characterization techniques combined with theoretical calculations reveal that sulfur vacancies at MoS2 edges are the active sites and the selective production of formate is enabled via a completely new water‐mediated hydrogenation mechanism, in which surface OH* and H* species in dynamic equilibrium with water serve as moderate hydrogenating agents for CO2 with residual O* reduced by hydrogen. This study provides a new route for developing low‐cost high‐performance catalysts for CO2 hydrogenation to formate.

Conversion of CO2 Hydrogenation to Methanol over K/Ni Promoted MoS2/MgO Catalyst

The chemical transformation of carbon dioxide (CO2) not only reduces the amount of carbon dioxide emitted into the Earth’s atmosphere by humans, but also produces carbon compounds that can be used as precursors for chemical and fuel production. Herein, a selective catalytic conversion of carbon dioxide to methanol is achieved by a bifunctional molybdenum disulfide catalyst (MoS2) with magnesium oxide and nickel and potassium promoters. Molybdenum disulfide prepared by the supercritical ethanol method has a large specific surface area and presents good catalytic performance with high methanol selectivity when loaded with potassium (K) and nickel (Ni) promoters. In addition, the catalysts were evaluated and it was founded that the addition of the K-promoter improved methanol selectivity. This research provides a new strategy for improved product selectivity and space–time yield (STY) of methanol in CO2 hydrogenation.

Review of Molybdenum Disulfide Research in Slurry Bed Heavy Oil Hydrogenation.

With the growing demand for gasoline and diesel fuel and the shortage of conventional oil reserves, there has been extensive interest in upgrading technologies for unconventional feedstocks such as heavy oil. Slurry bed reactors with high tolerance to heavy oil have been extensively investigated. Among them, dispersive MoS2 is favored for its excellent hydrogenation ability for heavy oil even under harsh reaction conditions such as high pressure and high temperature, its ability to effectively prevent damage to equipment from deposited coke, and its ability to meet the requirement of high catalyst dispersion for slurry bed reactors. This paper reviews the relationship between the structure and hydrogenation effectiveness of dispersive molybdenum disulfide, the hydrogenation mechanism, and the improvement of its hydrogenation performance by adding defects and compares the application of molybdenum disulfide in heavy oil hydrogenation, desulfurization, deoxygenation, and denitrification. It is found that the current research on dispersive molybdenum disulfide catalysts focuses mostly on the reduction of stacking layers and catalytic performance, and there is a lack of research on the lateral dimensions, microdomain regions, and defect sites of MoS2 catalysts. The relationship between catalyst structure and hydrogenation effect also lags far behind the application of MoS2 in the precipitation of hydrogen, etc. Oil-soluble and water-soluble MoS2 catalysts eventually need to be converted to a solid sulfide state to have hydrogenation activity. The conversion history of soluble catalysts to solid-type catalysts and the key to their improved catalytic effectiveness remain unclear.

Study on Nickel-induced 1T/2H MoS2 nanostructures in realizing efficient electrocatalysts for hydrogen evolution reaction

• Rational design and successfully prepared Ni-induced 1T/2H MoS 2 . • Ni-induced 1T/2H MoS 2 exhibits efficient HER catalytic performance. • The Ni-ions are favorable for enhancing the HER performance. Two-dimensional (2D) molybdenum disulfide (MoS 2 ) catalysts have gained great attention in several applications due to their unique properties as well as their tunable electronic structures. Fabrication of cost-effective and highly efficient electrocatalysts is vital for water splitting. Herein, we have synthesized nickel (Ni) induced mixed-phase (1T/2H) MoS 2 by solvothermal method and have studied its characteristics to be used for hydrogen evolution reaction (HER). The doping of Ni in MoS 2 is aimed at increasing the efficiency of HER performance and it has been proved to be a highly effective HER catalyst in an acidic medium. Ni-doped (9%) MoS 2 achieved the lowest overpotential of 127 mV for the HER at 10 mA cm −2 and a Tafel slope of 86 mV dec -1 among the other concentrations of Ni-doping studied. This work demonstrates the constructive outcome of doping the catalyst for HER and provides a pragmatic way for obtaining earth-abundant electrocatalysts.

Micromachined dimples on carbon electrode for enhancing electrochemical reaction

Coating catalyst particles on carbon gas diffusion electrode (GDE) is a common application for fabricating membrane electrode assembly (MEA) where the catalyst layer is formed in between the microporous carbon electrode and the polymer electrolyte membrane (PEM). In this study, we created micro-dimples on the surface of the GDE using laser-plasma to increase the open area of original pores, which leads to substantial enhancement in the electrochemical reaction. Scanning electron microscopy analysis of the surface processed carbon electrode shows that the electrode surface machining increases natural pore size up to ∼ 15 times and facilitates to accommodate most of the geometrically non-uniform Molybdenum disulfide catalyst particles. Electrochemical measurement results indicate that the micro-machined electrode with a dimple density of 0.16 cm2dimple/cm2electrode enhances the electrochemical reaction by 21%. Our PEM electrolysis tests also reveal that the current density can be increased up to 64% using MEA manufactured through the hot-pressing process along with the micro-machining technique. This study opens up the route for improving the performance of MEA in various potential applications such as water electrolysis and fuel cells.

CO2 adsorption and dissociation on single and double iron atomic molybdenum disulfide catalysts: A DFT study

Efficient two-dimensional molybdenum disulfide (MoS2) catalysts have not been developed for CO2 reduction. CO2 direct dissociation is the first step and rate determining step for CO2 decomposition reaction. The single and double Fe atomic MoS2 catalysts as well as pristine MoS2 and single S vacancy MoS2 were investigated to explore both adsorption and direct dissociation of CO2. It was found that a sulfur vacancy as well as Fe deposition and doping promoted the adsorption and direct dissociation of CO2 on MoS2. Double Fe atomic MoS2 catalysts had lower energy barrier for CO2 direct dissociation than single Fe atomic MoS2 catalysts. The case with two Fe atoms doped on the same Mo atom of MoS2 had the largest binding energy, highest adsorption energy, and lowest energy barrier among the six types of catalysts investigated. This system also had the highest Bader charge transfer, largest density of states change, and the most obvious electron density differences when adsorbing CO2. A linear relationship was found between the energy barrier and adsorption energy. Fe···O and Fe···C-O bonds were formed for the transition states of CO2 direct dissociation by the two Fe doped on the same Mo atom of MoS2 catalyst whereas only a Fe···O bond was formed for other Fe modified MoS2 catalysts.

Defected molybdenum disulfide catalyst engineered by nitrogen doping for advanced lithium–oxygen battery

Rechargeable lithium–oxygen (Li–O2) batteries have great potential for electric vehicles and grid energy storage system. The cathode catalysts play a crucial role in accelerating the oxygen reaction kinetics for improving battery performance. Herein, we employ hetero-atom doping method by combining hydrothermal reaction and ammonia-atmosphere calcination to introduce defects in MoS2 catalyst. The experimental results reveal the fabricated N-doped MoS2 (denoted as N-MoS2) catalysts introduced with abundant lattice defects while maintains the crystal structure of MoS2. The lithium–oxygen batteries with N-MoS2 catalyst as cathode show high initial specific capacity of 5500 mAh g–1 at 100 mA g–1 with good reversibility and efficiency. And the N-MoS2 cathode exhibits good rate capability and cycle stability up to 100 cycles. We reveal that the porous structure and lattice defects promote the exposition of active sites, resulting in higher electrochemical activity for oxygen reduction and the decomposition of discharge products. This work provides a promising avenue for constructing a bi-functional defected molybdenum disulfide catalyst by nitrogen doping in Li–O2 batteries.

Design and on-Sun Testing of Tandem III-V Photoelectrochemical Water-Splitting Systems

Photoelectrochemical (PEC) water-splitting systems utilize sunlight to directly split water to hydrogen and oxygen, providing a storable chemical fuel.1 While a variety of semiconductor material systems have demonstrated unassisted solar hydrogen production, III-V semiconductors have shown the highest reported solar-to-hydrogen (STH) conversion efficiencies and best device longevities.2–4 However, to date, work in the field has focused mostly on laboratory conditions, with few PEC systems having been tested outdoors using natural sunlight.In this work, we design III-V semiconductor systems with a molybdenum disulfide catalyst layer and demonstrate unassisted PEC hydrogen generation on-sun. First, a window and capping layer in conjunction with the MoS2 catalytic protection layer are shown to improve the photovoltage and durability of a single-junction pn-GaInP2 photocathode over a MoS2/pn-GaInP2 photocathode. Translating this top cell architecture to a tandem absorber device allows for more meaningful outdoor measurements and improved unassisted water-splitting performance. Specifically, we employ a tandem, lattice-matched GaInP2/GaAs (1.8/1.4 eV bandgaps) system that has been developed with high quality fabrication and yields>10% STH efficiency.2,3 An on-sun photoreactor platform was designed for PEC benchmarking and material testing that incorporates a 2-axis solar tracker and gas collection system.5 Insolation and environmental instrumentation at the co-located NREL Solar Radiation Research Laboratory provide a full record of the solar irradiance and environmental conditions, allowing for more accurate benchmarking of on-sun performance. PEC device characteristics were probed via current-voltage and chronoamperometry measurements under both natural and simulated sunlight illumination, while material structure is probed by XPS and SEM.The MoS2-protected tandem absorbers exhibit >10% STH efficiency under both laboratory and on-sun conditions. During a day of PEC testing under natural sunlight, >11 standard mL of hydrogen is generated with no applied bias. We will discuss challenges in catalyst and semiconductor stability and in cell design that limit PEC durability and hydrogen yield.

Novel magnetic carbon supported molybdenum disulfide catalyst and its application in residue upgrading

A novel hybrid material consisted of carbon covered Fe3O4 nanoparticles and MoS2 nanoflower (FCM) was designed and prepared by micelle-assisted hydrothermal methods. Multiple techniques, including X-Ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) were employed to characterize it. The results show that FCM has a flower-like morphology with a 330 nm Fe3O4 core as well as 70 nm highly crystalline MoS2 shell. FCM is superparamagnetic with a saturation magnetization of 35 emu g−1. Then hydrocracking of Canadian bitumen residue (CBR) was applied to estimate its catalytic activity. The results show that FCM exhibits superior catalytic hydrocracking activity compared to bulk MoS2 and commercial oil-dispersed Mo(CO)6 by the same Mo loading. Further measurement by elemental analysis, XPS and XRD reveals that the MoS2 nanoflower with abundant catalytic active sites and covered carbon layer with anti-coke ability donate to the superior upgrading performance. Besides, the catalysts can be easily recovered by the external magnetic field. This work provides a novel kind magnetic nanocatalyst which is potential for slurry-phase hydrocracking applications.

Active site manipulation in MoS2 cluster electrocatalysts by transition metal doping.

The development of non-platinum group metal catalysts for the hydrogen evolution reaction (HER) in water electrolyser devices is essential for their widespread and sustainable deployment. In recent years, molybdenum disulfide (MoS2) catalysts have received significant attention as they not only exhibit good electrocatalytic HER activity but also, crucially, acid-stability. However, further performance enhancement is required for these materials to be competitive with Pt and to that end transition metal doping of MoS2 has been explored as a route to further increasing its catalytic activity. In this work, cluster beam deposition was employed to produce controlled cobalt-doped MoS2 clusters (MoS2-Co). We demonstrate that, in contrast to previous observations of performance enhancement in MoS2 resulting from nickel doping (MoS2-Ni), the introduction of Co has a detrimental effect on HER activity. The contrasting behaviours of Ni and Co doping are rationalized by density functional theory (DFT) calculations, which suggest that HER-active surface vacancies are deactivated by combination with Co dopant atoms, whilst their activity is retained, or even partially enhanced, by combination with Ni dopant atoms. Furthermore, the adatom dopant-vacancy combination kinetics appear to be more than three orders of magnitude faster in MoS2-Co than for MoS2-Ni. These findings highlight a fundamental difference in the influence of transition metal dopants on the HER performance of MoS2 electrocatalysts and stress the importance of considering surface atomic defects when predicting their behaviour.

Efficient All-2D Amorphous Cobalt Sulfide Nanosheets/Multilayered Molybdenum Disulfide Hybrid Heterojunction Catalyst for Electrochemical Hydrogen Evolution.

Hydrogen energy is considered to be a critical environmentally friendly and widely sourced renewable energy source that can be used as an alternative to fossil fuels. At present, the preparation of hydrogen (H2) mainly depends on traditional fossil fuels. In order to achieve sustainable development of environmental protection, great attention has been paid to the preparation of H2 by electrocatalysis, photocatalysis, and photoelectrochemistry. Here, it is reported for the first time that a novel active catalyst for the hydrogen evolution reaction, consisting of all‐2D amorphous nanosheets/2D crystal layer heterojunction structure and without any noble metal (no precious metals are present in the preparation or measuring), is almost entirely fabricated by laser ablation in liquid (LAL) growth of amorphous cobalt sulfide on the surface of multilayered molybdenum disulfide. In acidic media, the amorphous cobalt sulfide nanosheets/multilayered molybdenum disulfide (a‐CoS/MoS2) catalyst exhibits fast hydrogen evolution kinetics with onset potential of −147 mV and a Tafel slope of 126 mV per decade, which is much better than only the amorphous cobalt sulfide and molybdenum disulfide layer. The high hydrogen evolution activity of the amorphous cobalt sulfide nanosheets/multilayered molybdenum disulfide hybrid is likely due to the unique electrocatalytic synergistic effects between hydrogen evolution‐active amorphous cobalt sulfide nanosheets and layered crystal molybdenum disulfide materials, as well as the much‐increased catalytic sites. This work provides a new general route based on all‐2D amorphous nanosheets/2D crystal structure for designing and preparing novel layered materials with effectively manipulated catalytic properties and active functionality surface.