A facile process was developed to synthesize layered MoS(2)/graphene (MoS(2)/G) composites by an l-cysteine-assisted solution-phase method, in which sodium molybdate, as-prepared graphene oxide (GO), and l-cysteine were used as starting materials. As-prepared MoS(2)/G was then fabricated into layered MoS(2)/G composites after annealing in a H(2)/N(2) atmosphere at 800 °C for 2 h. The samples were systematically investigated by X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and high-resolution transmission electron microscopy. Electrochemical performances were evaluated in two-electrode cells versus metallic lithium. It is demonstrated that the obtained MoS(2)/G composites show three-dimensional architecture and excellent electrochemical performances as anode materials for Li-ion batteries. The MoS(2)/G composite with a Mo:C molar ratio of 1:2 exhibits the highest specific capacity of ∼1100 mAh/g at a current of 100 mA/g, as well as excellent cycling stability and high-rate capability. The superior electrochemical performances of MoS(2)/G composites as Li-ion battery anodes are attributed to their robust composite structure and the synergistic effects between layered MoS(2) and graphene.
A facile process was developed to synthesize MoS(2)/graphene nanosheet (GNS) composites by a one-step in situ solution-phase method. These MoS(2)/GNS composites therefore exhibit extraordinary capacity, i.e., up to 1300 mA h g(-1), and excellent rate capability and cycling stability as an anode material for lithium ion batteries.
Exploiting noble-metal-free cocatalysts is of huge interest for photocatalytic water splitting using solar energy. Here we report a composite material consisting of CdS nanocrystals grown on the suface of a nanosized MoS2/graphene hybrid as a high-performance noble-metal-free photocatalyst for H2 evolution under visible light irradiation. Through the optimizing of each component proportion, the MoS2/G-CdS composite showed the highest photocatalytic H2 production activity when the content of the MoS2/graphene cocatalyst is 2.0 wt % and the molar ratio of MoS2 to graphene is 1:2. The photocatalytic H2 evolution activity of the proposed MoS2/G-CdS composite was tested and compared in Na2S-Na2SO3 solution and lactic acid solution. A 1.8 mmol/h H2 evolution rate in lactic acid solution corresponding to an AQE of 28.1% at 420 nm is not only higher than the case in Na2S-Na2SO3 solution of 1.2 mmol/h but also much higher than that of Pt/CdS in lactic acid solution. The relative mechanism has been investigated. It is believed that this kind of MoS2/G-CdS composite would have great potential as a promising photocatalyst with high efficiency and low cost for photocatalytic H2 evolution reaction.
Solar-driven reduction of dinitrogen (N ) to ammonia (NH ) is severely hampered by the kinetically complex and energetically challenging multielectron reaction. Oxygen vacancies (OVs) with abundant localized electrons on the surface of bismuth oxybromide-based semiconductors are demonstrated to have the ability to capture and activate N , providing an alternative pathway to overcome such limitations. However, bismuth oxybromide materials are susceptible to photocorrosion, and the surface OVs are easily oxidized and therefore lose their activities. For realistic photocatalytic N fixation, fabricating and enhancing the stability of sustainable OVs on semiconductors is indispensable. This study shows the first synthesis of self-assembled 5 nm diameter Bi O Br nanotubes with strong nanotube structure, suitable absorption edge, and many exposed surface sites, which are favorable for furnishing sufficient visible light-induced OVs to realize excellent and stable photoreduction of atmospheric N into NH in pure water. The NH generation rate is as high as 1.38 mmol h g , accompanied by an apparent quantum efficiency over 2.3% at 420 nm. The results presented herein provide new insights into rational design and engineering for the creation of highly active catalysts with light-switchable OVs toward efficient, stable, and sustainable visible light N fixation in mild conditions.
Through a facile and effective strategy by employing lithium molten salts the controlled synthesis of 2H- and 1T-MoS monolayers with high-yield production is achieved. Both phases of MoS monolayers exhibit high stabilities. When used as a catalyst for hydrogen evolution, these phased MoS monolayers deliver respective advantages in the field of electro- and photo-catalytic hydrogen evolution.
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