Aruna K Kunhiraman; Bradha Madhavan
Abstract
Facile solvothermal route was adopted for the synthesis of Co2xMo1-xS2 with x = 0, 0.05 and 0.1. Higher HER activity was exhibited by x = 0.1 in Co doped MoS2, with a current density -140 mAcm -2 at an overpotential of -100 mV. At lower overpotential both the compositions exhibited almost same activity, ...
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Facile solvothermal route was adopted for the synthesis of Co2xMo1-xS2 with x = 0, 0.05 and 0.1. Higher HER activity was exhibited by x = 0.1 in Co doped MoS2, with a current density -140 mAcm -2 at an overpotential of -100 mV. At lower overpotential both the compositions exhibited almost same activity, whereas with the increase in the overpotential and under continuous electrochemical operation, the active sites of composition with x = 0.1 was triggered and it was reflected in its HER activity.
V. Thiruvengadam; Braj Bhusan Singh; Palash Kumar Manna; Subhankar Bedanta
Abstract
Molybdenum disulfide (MoS2) is one among the transition-metal dichalcogenide (TMD) family which exhibits exotic physical properties at their mono-layer limit. We report a facile way to fabricate stoichiometric, crystalline and star shaped MoS2 film. In this work, ultra-thin MoS2 films were fabricated ...
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Molybdenum disulfide (MoS2) is one among the transition-metal dichalcogenide (TMD) family which exhibits exotic physical properties at their mono-layer limit. We report a facile way to fabricate stoichiometric, crystalline and star shaped MoS2 film. In this work, ultra-thin MoS2 films were fabricated by two step process (i) RF sputtering of MoS2 target followed by (ii) sulfurization to improve stoichiometry and crystallinity. In order to study the effect of sulfurization temperature on sputtered MoS2, sulfurization has been performed at five different temperatures - 700, 750, 775, 800 and 825°C. Surface morphology of as sputtered and sulfurized MoS2 films were characterized using optical and scanning electron microscopes. Crystallinity and layer thickness of the fabricated MoS2 films were estimated by using Laser Raman spectroscopy. These results confirm that as sputtered MoS2 films are discontinuous, amorphous in nature and it crystalizes into a layered structure during sulfurization at temperature ≥ 750°C. It was observed that at sulfurization temperature of 800°C, the nucleated crystallites well grown into a star shaped crystalline MoS2 with their thickness vary between 2 and 3 mono-layers. These star shapes can provide more surface area/edges that can be exploited to enhance the efficiency of gas sensors.
Akhilesh Pandey; Shankar Dutta; Anand Kumar; R. Raman; Ashok K. Kapoor; R Muralidhran
Abstract
Molybdenum-di-sulfide (MoS2) is being considered as an alternative 2-D material to graphene. Deposition of ultrathin MoS2 layer from bulk MoS2 sample is an important criterion in determining the viability of its application. This paper discusses about growth and characterization of bulk MoS2 pellet ...
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Molybdenum-di-sulfide (MoS2) is being considered as an alternative 2-D material to graphene. Deposition of ultrathin MoS2 layer from bulk MoS2 sample is an important criterion in determining the viability of its application. This paper discusses about growth and characterization of bulk MoS2 pellet from MoS2 powder and exfoliation of MoS2 layer from it. The MoS2 pellets were sintered at different temperatures (500 - 850 ° in nitrogen atmosphere. The sintered samples were found to be polycrystalline in nature with hexagonal flakes of 100 nm – 1.0 µm sizes. In addition to MoS2 phase, surface of the bulk samples also has also some MoO3 phase content, which was found to decrease with the increase in sintering temperature, confirmed by XRD. The optical absorption study showed MoS2 absorptions around 1.82 eV, 2.01 eV due to spin orbit and direct band to band absorption from ?k-k valley. The sintered MoS2 samples were found to have characteristic Raman peaks of A1g and E2g with a separation of 26.5 cm -1 . Ultrathin MoS2 layers, exfoliated from the sintered sample, showed the reduced separation between Raman peaks A1g and E2g of 24.5 cm -1 few layer MoS2.
Bablu Mukherjee; Asim Guchhait; Yinthai Chan; Ergun Simsek
Abstract
We have studied the optical absorptance of lead sulfide (PbS) quantum dot (QD) coated thin crystalline layered material (TCLM) experimentally and numerically. Starting with the synthesis, fabrication and characterizations, a sample of PbS QDs deposited on trilayer molybdenum disulphide (MoS2) thin film ...
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We have studied the optical absorptance of lead sulfide (PbS) quantum dot (QD) coated thin crystalline layered material (TCLM) experimentally and numerically. Starting with the synthesis, fabrication and characterizations, a sample of PbS QDs deposited on trilayer molybdenum disulphide (MoS2) thin film has been probed locally using a reflection spectrometer set-up. Since transmittance is needed to calculate the absorbtance of the QD film/TCLM sample, we run a set of simulations using a 3D finite-difference time-domain full-wave electromagnetic solver. Based on the agreement between experimental and numerical results for the reflectance spectra, which verifies the accuracy of our QD and TCLM modelling, we have calculated the absorptance. Unlike metal nanoparticle decorated TCLMs in which metal nanoparticles act like induced dipoles and enhance the absorptance, here we have not observed the similar effect; rather we have found that the absorptance of QD film/TCLM sample is almost equal to the summation of QDs’ and TCLM’s individual absorptance in the wavelength range of 450-800 nm.