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Plasmonic MoO2 nanospheres assembled on graphene oxide for highly sensitive SERS detection of organic pollutants
摘要： The molybdenum oxide and graphene oxide (MoO2/GO) nanocomposite has been fabricated via simple hydrothermal assisted synthesis using Mo and MoO3 as precursors. The MoO2 nanospheres with porous hollow structure are assembled onto GO nanosheets. Profiting from the plasmonic effects of MoO2 and synergistic effect of MoO2 and GO, this hybrid nanomaterial exhibits significantly enhanced surface enhanced Raman scattering (SERS) activity for organic pollutants. The detection limit for rhodamine 6G (R6G) is 1.0 × 10?9 M, and the maximum enhancement factor (EF) reaches up to 1.05 × 107, which is the best among the semiconductor-based SERS materials. For practical application, the MoO2/GO SERS substrates are also applied to detect Methylene blue (MB) in river water, and the detection limit (1.0 × 10?8 M) can be acquired. Pyrene is also chosen as probe molecule, and quantitative determination is achieved with detection limit of 1.0 × 10?7 M. These demonstrate the well feasibility for multi-molecule detection. Furthermore, the nanocomposite displays high stability, reproducible stability, and acid and alkali resistance.
关键词： Organic pollutants,Plasmonic effect,SERS,Graphene oxide,Detection,MoO2
更新于2025-11-14 15:27:09
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Plasmonic MoO2 as co-catalyst of MoS2 for enhanced photocatalytic hydrogen evolution
摘要： Generally, photocatalytic water splitting on MoS2 nanomaterials is restricted owing to the high carrier recombination and limited utilization of the visible light. This study describes the enhancement of the MoS2-catalysed hydrogen evolution by incorporating metallic MoO2 as a co-catalyst introduced by coupling with MoS2 nanosheets through a facile calcination strategy, forming a Schottky junction between MoO2 and MoS2. The localized surface plasmon resonance effect induced by the oxygen vacancies and favourable Fermi lever position of MoO2 lead to a broad spectral response and a significant improvement in the exciton generation and dissociation. The electron gets transferred from the conduction band (CB) of MoS2 to MoO2, wherein MoO2 acts as an ‘electron pool’ that gathers the photoexcited electrons, which are rapidly shuttled to the surface of MoO2, where the redox reaction occurs due to its great metallic conductivity. Resultantly, a 242% increment in the production of hydrogen gas by MoS2/MoO2 is achieved in comparison with that of the MoS2 nanosheets.
关键词： Photocatalytical hydrogen production,co-catalysts,MoS2/MoO2,LSPR effect,Schottky junction
更新于2025-09-19 17:13:59
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Synthesis of MoS2–MoO2/MWCNTs counter electrode for high-efficient dye-sensitized solar cells
摘要： In this work, MoS2–MoO2 and MoS2–MoO2/MWCNTs counter electrodes (CEs) for dye-sensitized solar cells (DSSCs) were prepared by sulfurization of a one-pot hydrothermally obtained MoO2 film and MoO2/MWCNTs composite film on fluorine-doped tin oxide glasses at 500?°C for 2?h in argon atmosphere. The promoted MoS2 particles on a surface of MoS2–MoO2 and MoS2–MoO2/MWCNTs films were identified by X-ray diffraction to have a hexagonal structure. Morphology of MoO2, MoO2/MWCNTs, MoS2–MoO2, and MoS2–MoO2/MWCNTs CEs was studied using field emission scanning electron microscope and transmission electron microscope. Functional groups in MoS2–MoO2/MWCNTs sample were identified by Raman spectroscopy. Results of cyclic voltammetry and electrochemical impedance spectroscopy displayed a high electrocatalytic activity performance and low charge transfer resistance of MoS2–MoO2/MWCNTs CE as compared to those of MoO2, MoO2/MWCNTs, and MoS2–MoO2 CEs. Interestingly, the DSSC based on MoS2–MoO2/MWCNTs CE could provide the higher power conversion efficiency of 7.79% compared to that of 7.26% for Pt-based DSSC.
关键词： electrocatalytic activity,dye-sensitized solar cells,counter electrode,MoS2–MoO2,MWCNTs
更新于2025-09-12 10:27:22
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Mechanistic insights into the phenomena of increasing capacity with cycle number: using pulsed-laser deposited MoO <sub/>2</sub> thin film electrodes
摘要： Lithium ion batteries typically lose capacity or energy storage density (i.e. capacity fading) over the course of extended cycling which can be problematic for applications and appears to be exaggerated when high current rates are used. However, in some cases fluctuations in capacity with cycle number and even increases in capacity with cycle number are noted with predominantly thin film based electrodes. Here we demonstrate the synthesis and in-depth characterisation of laser deposited MoO2 thin film anodes and its unconventional mechanism. A MoO2 electrode shows an initial capacity of 79 mA h g?1 which increases to capacities of 600 mA h g?1 at 15.8 A g?1 after 90 000 cycles. A maximum capacity of 1714 mA h g?1 was achieved in an electrode cycled at 1.5 A g?1 for over 3800 cycles, the highest recorded capacity in MoOx anodes to date. The most intriguing aspects of this work is the fact that capacity is shown to fluctuate and typically increase well above the theoretical capacity of MoO2. A combination of electrochemical cycling, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, focused ion beam milling and transmission electron microscopy at various states of cycling is used to illustrate a proposed mechanism. The mechanism illustrated is based on exfoliation of layers of MoO2 off the pulsed laser deposition (PLD) grown MoO2 electrodes during cycling that creates additional surface area and easier access for Li-ions to both adsorb to the surface and insert/react with the host material. Further features in the capacity evolution are rationalised by this mechanism and methods to control the capacity evolution are detailed. These results present a rational explanation for when an electrode undergoes a substantial increase in capacity over its extended cycling life.
关键词： pulsed laser deposition,MoO2 thin film anodes,exfoliation mechanism,Lithium ion batteries,capacity increase
更新于2025-09-12 10:27:22
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Effect of the Substrate Temperature on the Structural and Morphological Properties of MoO2 Thin Films Obtained by Pulsed Injection MOCVD
摘要： Molybdenum oxides is of great technological interest due to their outstanding optical, electronic and catalytic properties. In this work, molybdenum dioxide (MoO2) thin films were deposited onto Si wafers and stainless steel substrates at different substrate temperatures. The growth of the films was achieved by using a vertical metal organic chemical vapor deposition reactor working in pulsed injection mode. A powder of molybdenum hexacarbonyl mixed in a toluene solution was used as precursor. An effective pulsed injection system to supply the precursor, usually used for fuel injection in internal combustion devices, delivers a precise amount of liquid precursor to the reactor through injectors, whose pulse intervals (injection frequency) are controlled by a computer-driven system. The use of a liquid solution as precursor along with the experimental parameters provide thermodynamically favorable conditions to fabricate a thin solid film, homogenously deposited onto the whole substrate. The MoO2 film structure and morphology were studied by X-ray diffraction, Raman scattering spectroscopy and scanning electron microscopy. Moreover, a comparative study was undertaken whereby the catalytic activity of stainless steel substrate for hydrogen evolution reaction was related to that of MoO2 thin film.
关键词： catalytic activity,MOCVD,MoO2 thin films,molybdenum oxides
更新于2025-09-09 09:28:46