MoS2(1-x) Se2x single-layer films are prepared using a mixture of organic selenium and sulfur precursors as well as a solid molybdenum source. The direct bandgaps are found to scale nearly linearly with composition in the range of 1.87 eV (pure single-layer MoS2 ) to 1.55 eV (pure single-layer MoSe2 ) permitting straightforward bandgap engineering.

Single-layer MoS 2 is proving to be a versatile material for a wide variety of electronic, optical, and chemical applications. Sulfur depletion, without destabilization of the single layer, is considered a prudent way for making the basal plane of the layer catalytically active. Based on the results of our density-functional-theory examination of vacancy structures on one side of an MoS 2 layer, we show that the formation energy per sulfur vacancy is the lowest (energetically favorable) when the vacancies form a row and that the longer the row, the lower the formation energy. In addition, we find that the lowest energy barrier for the diffusion of sulfur vacancy at the row structures through the exchange of a vacancy with a nearby sulfur atom is 0.79 eV and that this barrier increases as the row elongates. We also evaluate the propensity for catalytic activity of an MoS 2 layer with two types of sulfur-vacancy structures (row and patch) and find the energetics for alcohol synthesis from syngas to be more favorable for the layer with a sulfur-vacancy patch.

The high intrinsic spin and long spin relaxation time of manganese-12-acetate (Mn(12)) makes it an archetypical single molecular magnet. While these characteristics have been measured on bulk samples, questions remain whether the magnetic properties replicate themselves in surface supported isolated molecules, a prerequisite for any application. Here we demonstrate that electrospray ion beam deposition facilitates grafting of intact Mn(12) molecules on metal as well as ultrathin insulating surfaces enabling submolecular resolution imaging by scanning tunneling microscopy. Using scanning tunneling spectroscopy we detect spin excitations from the magnetic ground state of the molecule at an ultrathin boron nitride decoupling layer. Our results are supported by density functional theory based calculations and establish that individual Mn(12) molecules retain their intrinsic spin on a well chosen solid support.

We find that nearly monodisperse copper oxide nanoparticles prepared via the thermal decomposition of a Cu(I) precursor exhibit exceptional activity toward CO oxidation in CO/O 2 /N 2 mixtures. Greater than 99.5% conversion of CO to CO 2 could be achieved at temperatures less than 250°C for over 12 h. In addition, the phase diagram and pathway for CO oxidation on Cu 2 O (100) is computed by ab initio methods and found to be in qualitative agreement with the experimental findings.Nanoparticles offer a larger surface-to-volume ratio and a higher concentration of partially coordinated surface sites than the corresponding bulk materials. The unique properties of nanoparticles are due to a strong interplay between elastic, geometric, and electronic parameters, as well as the effects of interactions with the support. The result of these features is often improved physical and chemical properties compared to the bulk material. It is for these reasons that heterogeneous catalysis at nanoparticle surfaces is currently under intense investigation in the catalysis community at large. 1,2 Conventional supported catalysts are generally produced by impregnation of a support medium with the desired metal ions followed by thermal treatments that result in small and dispersed active catalytic sites. 3,4 Many traditional catalysts based on the impregnation method 5,6 rely on the noble metals, in particular platinum, as the source for high activity. Such metals are recognized as a scarce resource as well as a limiting step in the development of viable energy alternatives to petroleum. Automotive exhaust catalysts (the three way catalyst) and fuel cells are examples of this tenet. 5,6 Any new system that overcomes these limitations will be invaluable.There are several important processes in heterogeneous catalysis where removal of carbon monoxide is either desired or absolutely necessary, such as in the postprocessing of Syngas 7 to produce hydrogen as an energy source for use in fuel cells. 8,9 A byproduct of this reaction is CO; however, trace amounts of CO (>10 ppm) can poison a fuel cell electrode, drastically reducing its efficiency. [10][11][12] The CuCu 2 O-CuO system has been known to facilitate oxidation reactions in the bulk, suggesting it has potential as a costeffective substitute for noble metals in various catalytic systems. [13][14][15] Here we describe a cheap, effective method of using copper oxide nanoparticles loaded onto silica gel as an exceptional catalyst toward CO oxidation at relatively low temperatures. Over sustained periods of time, conversions of 99.5% of CO to CO 2 are routinely observed and the catalyst structure is retained during the reaction. For example, during a 50 h period with the same ∼10 mg sample of copper oxide nanoparticles, over 30 L of CO is converted to CO 2 with an average conversion of 98 ( 1%.With recent developments in nanoparticle synthesis leading to the ability to control size, reproducibility, and structural complexity, it becomes urgent to define specific target structu...