Browse
Submit Data
Databases
API
Help

Dataset Information

27 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Ultrasonication-assisted synthesis of 2D porous MoS₂/GO nanocomposite catalysts as high-performance hydrodesulfurization catalysts of vacuum gasoil: Experimental and DFT study.

ABSTRACT: In this study, a novel, simple, high yield, and scalable method is proposed to synthesize highly porous MoS₂/graphene oxide (M-GO) nanocomposites by reacting the GO and co-exfoliation of bulky MoS₂ in the presence of polyvinyl pyrrolidone (PVP) under different condition of ultrasonication. Also, the effect of ultrasonic output power on the particle size distribution of metal cluster on the surface of nanocatalysts is studied. It is found that the use of the ultrasonication method can reduce the particle size and increase the specific surface area of M-GO nanocomposite catalysts which leads to HDS activity is increased. These nanocomposite catalysts are characterized by XRD, Raman spectroscopy, SEM, STEM, HR-TEM, AFM, XPS, ICP, BET surface, TPR and TPD techniques. The effects of physicochemical properties of the M-GO nanocomposites on the hydrodesulfurization (HDS) reactions of vacuum gas oil (VGO) has been also studied. Catalytic activities of MoS₂-GO nanocomposite are investigated by different operating conditions. M9-GO nanocatalyst with high surface area (324 m²/g) and large pore size (110.3 Å), have the best catalytic performance (99.95%) compared with Co-Mo/γAl₂O₃ (97.91%). Density functional theory (DFT) calculations were also used to elucidate the HDS mechanism over the M-GO catalyst. It is found that the GO substrate can stabilize MoS₂ layers through weak van der Waals interactions between carbon atoms of the GO and S atoms of MoS₂. At both Mo- and S-edges, the direct desulfurization (DDS) is found as the main reaction pathway for the hydrodesulfurization of DBT molecules.

SUBMITTER: Mahmoudabadi ZS

PROVIDER: S-EPMC8105686 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Electrochemical and SECM Investigation of MoS2/GO and MoS2/rGO Nanocomposite Materials for HER Electrocatalysis.

Project description:Development of advanced materials for electrocatalytic and photocatalytic water splitting is the key in utilization of renewable energy. In the present work, we have synthesized MoS2 nanoparticles embedded over the graphene oxide (GO) and reduced graphene oxide (rGO) layer for superior catalytic activity in the hydrogen evolution process (HER). The nanocomposite materials are characterized using different spectroscopic and microscopic measurements. A Tafel slope of ∼40 mV/decade suggested the Volmer-Heyrovsky mechanism for the HER process with MoS2/GO composite as the catalyst, which indicated that electrochemical desorption of hydrogen is the rate-limiting step. The small Tafel slope indicates a promising electrocatalyst for HER in practical application. MoS2/GO composite material has shown superior catalytic behavior compared to that of MoS2/rGO composite material. The HER catalytic activity of the catalysts is explored using scanning electrochemical microscopy (SECM) using the feedback and redox competition mode in SECM. The activation energy for HER activity was calculated, and the values are in the range of 17-6 kJ/mol. The lower value of activation energy suggested faster HER kinetics.

| S-EPMC6645306 | biostudies-literature

In situ observations of an active MoS2 model hydrodesulfurization catalyst.

Project description:The hydrodesulfurization process is one of the cornerstones of the chemical industry, removing harmful sulfur from oil to produce clean hydrocarbons. The reaction is catalyzed by the edges of MoS2 nanoislands and is operated in hydrogen-oil mixtures at 5-160 bar and 260-380 °C. Until now, it has remained unclear how these harsh conditions affect the structure of the catalyst. Using a special-purpose high-pressure scanning tunneling microscope, we provide direct observations of an active MoS2 model catalyst under reaction conditions. We show that the active edge sites adapt their sulfur, hydrogen, and hydrocarbon coverages depending on the gas environment. By comparing these observations to density functional theory calculations, we propose that the dominant edge structure during the desulfurization of CH3SH contains a mixture of adsorbed sulfur and CH3SH.

| S-EPMC6560102 | biostudies-literature

Site-dependent reactivity of MoS2 nanoparticles in hydrodesulfurization of thiophene.

Project description:The catalytically active site for the removal of S from organosulfur compounds in catalytic hydrodesulfurization has been attributed to a generic site at an S-vacancy on the edge of MoS2 particles. However, steric constraints in adsorption and variations in S-coordination means that not all S-vacancy sites should be considered equally active. Here, we use a combination of atom-resolved scanning probe microscopy and density functional theory to reveal how the generation of S-vacancies within MoS2 nanoparticles and the subsequent adsorption of thiophene (C4H4S) depends strongly on the location on the edge of MoS2. Thiophene adsorbs directly at open corner vacancy sites, however, we find that its adsorption at S-vacancy sites away from the MoS2 particle corners leads to an activated and concerted displacement of neighboring edge S. This mechanism allows the reactant to self-generate a double CUS site that reduces steric effects in more constrained sites along the edge.

| S-EPMC7459117 | biostudies-literature

Electronically Coupled 2D Polymer/MoS2 Heterostructures.

Project description:Emergent quantum phenomena in electronically coupled two-dimensional heterostructures are central to next-generation optical, electronic, and quantum information applications. Tailoring electronic band gaps in coupled heterostructures would permit control of such phenomena and is the subject of significant research interest. Two-dimensional polymers (2DPs) offer a compelling route to tailored band structures through the selection of molecular constituents. However, despite the promise of synthetic flexibility and electronic design, fabrication of 2DPs that form electronically coupled 2D heterostructures remains an outstanding challenge. Here, we report the rational design and optimized synthesis of electronically coupled semiconducting 2DP/2D transition metal dichalcogenide van der Waals heterostructures, demonstrate direct exfoliation of the highly crystalline and oriented 2DP films down to a few nanometers, and present the first thickness-dependent study of 2DP/MoS2 heterostructures. Control over the 2DP layers reveals enhancement of the 2DP photoluminescence by two orders of magnitude in ultrathin sheets and an unexpected thickness-dependent modulation of the ultrafast excited state dynamics in the 2DP/MoS2 heterostructure. These results provide fundamental insight into the electronic structure of 2DPs and present a route to tune emergent quantum phenomena in 2DP hybrid van der Waals heterostructures.

| S-EPMC9836045 | biostudies-literature

Laser-Synthesized 2D-MoS2 Nanostructured Photoconductors.

Project description:The direct laser synthesis of periodically nanostructured 2D transition metal dichalcogenide (2D-TMD) films, from single source precursors, is presented here. Laser synthesis of MoS2 and WS2 tracks is achieved by localized thermal dissociation of Mo and W thiosalts, caused by the strong absorption of continuous wave (c.w.) visible laser radiation by the precursor film. Moreover, within a range of irradiation conditions we have observed occurrence of 1D and 2D spontaneous periodic modulation in the thickness of the laser-synthesized TMD films, which in some cases is so extreme that it results in the formation of isolated nanoribbons with a width of ~200 nm and a length of several micrometers. The formation of these nanostructures is attributed to the effect that is known as laser-induced periodic surface structures (LIPSS), which is caused by self-organized modulation of the incident laser intensity distribution due to optical feedback from surface roughness. We have fabricated two terminal photoconductive detectors based on nanostructured and continuous films and we show that the nanostructured TMD films exhibit enhanced photo-response, with photocurrent yield increased by three orders of magnitude as compared to their continuous counterparts.

| S-EPMC10222115 | biostudies-literature

Ultrasonication-assisted liquid-phase exfoliation enhances photoelectrochemical performance in ?-Fe2O3/MoS2 photoanode.

Project description:This study successfully manufactured a p-n heterojunction hematite (?-Fe2O3) structure with molybdenum disulfide (MoS2) to address the electron-hole transfer problems of conventional hematite to enhance photoelectrochemical (PEC) performance. The two-dimensional MoS2 nanosheets were prepared through ultrasonication-assisted liquid-phase exfoliation, after which the concentration, number of layers, and thickness parameters of the MoS2 nanosheets were respectively estimated by UV-vis, HRTEM and AFM analysis to be 0.37 mg/ml, 10-12 layers and around 6 nm. The effect of heterojunction ?-Fe2O3/MoS2 and the role of the ultrasonication process were investigated by the optimized concentration of MoS2 in the forms of bulk and nanosheet on the surface of the ?-Fe2O3 electrode while measuring the PEC performance. The best photocurrent density of the ?-Fe2O3/MoS2 photoanode was obtained at 1.52 and 0.86 mA.cm-2 with good stability at 0.6 V vs. Ag/AgCl under 100 mW/cm2 (AM 1.5) illumination from the back- and front-sides of ?-Fe2O3/MoS2; these values are 13.82 and 7.85-times higher than those of pure ?-Fe2O3, respectively. The results of electrochemical impedance spectroscopy (EIS) and Mott-Schottky analysis showed increased donor concentration (2.6-fold) and decreased flat band potential (by 20%). Moreover, the results of IPCE, ABPE, and OCP analyses also supported the enhanced PEC performance of ?-Fe2O3/MoS2 through the formation of a p-n heterojunction, leading to a facile electron-hole transfer.

| S-EPMC7803682 | biostudies-literature

High conversion continuous flow exfoliation of 2D MoS2.

Project description:We report a low-cost and highly efficient process for exfoliating of MoS2 using an energy efficient vortex fluidic device (VFD). This method is high in green chemistry metrics in avoiding the use of auxiliary substances, and the process is scalable, with a conversion of as received MoS2 into 2D sheets at ∼73%.

| S-EPMC10662006 | biostudies-literature

Ultrasensitive all-2D MoS2 phototransistors enabled by an out-of-plane MoS2 PN homojunction.

Project description:Two-dimensional transition metal dichalcogenide-based photodetectors have demonstrated potential for the next generation of 2-dimensional optoelectronics. However, to date, their sensitivity has not been superior to that of other technologies. Here we report an ultrasensitive two-dimensional photodetector employing an in-plane phototransistor with an out-of-plane vertical MoS2 p-n junction as a sensitizing scheme. The vertical built-in field is introduced for the first time in the transport channel of MoS2 phototransistors by facile chemical surface doping, which separates the photo-excited carriers efficiently and produces a photoconductive gain of >105 electrons per photon, external quantum efficiency greater than 10%, responsivity of 7?×?104?A?W-1, and a time response on the order of tens of ms. This taken together with a very low noise power density yields a record sensitivity with specific detectivity [Formula: see text] of 3.5?×?1014 Jones in the visible and a broadband response up to 1000?nm.Photodetectors based on 2D transition metal dichalcogenides exhibit ever increasingly competitive performance, yet not superior to that of alternative technologies. Here, the authors devise a MoS2-based phototransistor with an out-of-plane junction, yielding a record detectivity combined with broadband response.

| S-EPMC5603552 | biostudies-literature

Epitaxial synthesis of Ni-MoS2/Ti3C2T x MXene heterostructures for hydrodesulfurization.

Project description:Hierarchical structures of 2D layered Ti3C2T x MXene hold potential for a range of applications. In this study, catalysts comprising few-layered MoS2 with Ti3C2T x have been formulated for hydrodesulfurization (HDS). The support Ti3C2T x was derived from MAX phases (Ti3AlC2) via a liquid-phase exfoliation process, while MoS2 was obtained from synthesized aqueous ammonium tetrathiomolybdate (ATM). Furthermore, a series of catalysts with different architectures was synthesized by confinement of ATM and/or the promoter Ni in Ti3C2T x at different mole ratios, through a thermal conversion process. The synthesized MoS2/Ti3C2T x and Ni-MoS2/Ti3C2T x catalysts were characterized using X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS), high-resolution transmission electron microscopy (HRTEM), and temperature-programmed reduction (TPR) measurements. The number of MoS2 layers formed on the Ti3C2T x support was calculated using Raman spectroscopy. The heterostructured few-layered MoS2/Ti3C2T x catalysts were applied in sulfur removal efficiency experiments involving thiophene. The active MoS2 sites confined by the Ti3C2T x enhanced hydrogen activation by proton saturation, and the electron charge stabilized the sulfur atom to facilitate hydrogenation reactions, leading to predominant formation of C4 hydrocarbons. The Ni-MoS2/Ti3C2T x showed the best activity at a promoter molar ratio of 0.3 when compared to the other catalysts. In particular, it is evident from the results that ATM and Ti3C2T x are potential materials for the in situ fabrication of hierarchical few-layered MoS2/Ti3C2T x catalysts for enhancing hydrodesulfurization activity in clean fuel production.

| S-EPMC9050720 | biostudies-literature

Frenkel-defected monolayer MoS2 catalysts for efficient hydrogen evolution.

Project description:Defect engineering is an effective strategy to improve the activity of two-dimensional molybdenum disulfide base planes toward electrocatalytic hydrogen evolution reaction. Here, we report a Frenkel-defected monolayer MoS2 catalyst, in which a fraction of Mo atoms in MoS2 spontaneously leave their places in the lattice, creating vacancies and becoming interstitials by lodging in nearby locations. Unique charge distributions are introduced in the MoS2 surface planes, and those interstitial Mo atoms are more conducive to H adsorption, thus greatly promoting the HER activity of monolayer MoS2 base planes. At the current density of 10 mA cm-2, the optimal Frenkel-defected monolayer MoS2 exhibits a lower overpotential (164 mV) than either pristine monolayer MoS2 surface plane (358 mV) or Pt-single-atom doped MoS2 (211 mV). This work provides insights into the structure-property relationship of point-defected MoS2 and highlights the advantages of Frenkel defects in tuning the catalytic performance of MoS2 materials.

| S-EPMC9033855 | biostudies-literature