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Post Info TOPIC: Hydrogen Production


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RE: Hydrogen Production
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Title: Amorphous molybdenum sulphide films as catalysts for electrochemical hydrogen production in water
Authors: Daniel Merki, Stéphane Fierro, Heron Vrubel and Xile Hu

Amorphous molybdenum sulphide films are efficient hydrogen evolution catalysts in water. The films are prepared via simple electro-polymerization procedures and are characterised by XPS, electron microscopy and electronic absorption spectroscopy. Whereas the precatalysts could be MoS3 or MoS2, the active form of the catalysts is identified as amorphous MoS2. Significant geometric current densities are achieved at low overpotentials (e.g., 15 mA cm-2 at = 200 mV) using these catalysts. The catalysis is compatible with a wide range of pHs (e.g., 0 to 13). The current efficiency for hydrogen production is quantitative. A 40 mV Tafel slope is observed, suggesting a rate-determining ion+atom step. The turnover frequency per active site is calculated. The amorphous molybdenum sulphide films are among the most active non-precious hydrogen evolution catalysts.

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Scientists at Penn State and the Virginia Commonwealth University have discovered a way to produce hydrogen by exposing selected clusters of aluminium atoms to water. The findings are important because they demonstrate that it is the geometries of these aluminium clusters, rather than solely their electronic properties, that govern the proximity of the clusters' exposed active sites. The proximity of the clusters' exposed sites plays an important role in affecting the clusters' reactions with water. The team's findings have been published in the Jan. 23 issue of the journal Science.

"Our previous research suggested that electronic properties govern everything about these aluminium clusters, but this new study shows that it is the arrangement of atoms within the clusters that allows them to split water. Generally, this knowledge might allow us to design new nanoscale catalysts by changing the arrangements of atoms in a cluster. The results could open up a new area of research, not only related to splitting water, but also to breaking the bonds of other molecules, as well" - A. Welford Castleman Jr., Eberly family distinguished chair in science and Evan Pugh professor in the Penn State Departments of Chemistry and Physics.

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