Apr
13
Hydrogen Production Made By Molybdenum Disulfide
April 13, 2016 | Leave a Comment
Scientists have created a molybdenum-based material that could be a low-cost alternative to platinum for splitting water to make hydrogen fuel. Sounds familiar because molybdenum disulfide (MoS2) is a common dry lubricant and an additive to lubrication oils and greases.
The Department of Energy scientists showed that a microwave synthesis technique helps create the new material into a layered material as a nanostructured form and gives the catalyst an improved ability to produce hydrogen.
Nanostructured sheets created using microwaves are envisioned here on an electrode surface for the hydrogen evolution reaction (green circles are molybdenum atoms, yellow circles are sulfur atoms). Image Credit: Department of Energy, Office of Science. Click image for the largest view.
A layered material containing MoS2 and sulfur shows great promise as a low-cost alternative to the platinum-based electrocatalysts. Prior research has shown that the activity is primarily in sites on the edges of the sheets.
Scientists at the Center for Nanoscale Materials have demonstrated the microwave synthesis technique helping to create nanostructured MoS2 catalysts with an energy competitive ability to produce hydrogen. Theoretical calculations show the microwave-assisted strategy works partially through a change in the interaction between the hydrogen and MoS2 edge sites when the space between individual layers of MoS2 nanosheets is increased. The increase in space also exposes a larger fraction of reactive sites along the edges of these surfaces where hydrogen can be produced.
The performance of the microwave-created MoS2 nanostructured material is among the best of current MoS2 catalysts, requiring only 0.1 V of extra voltage, compared to platinum, for the beginning of hydrogen evolution. Furthermore, the microwave method is more energy efficient than thermal synthesis methods, and it offers the possibility of designing tailored MoS2 catalysts through precise control of the interlayer distance.
Storing energy from sunlight or wind through water splitting inside the bonds of a hydrogen (H2) molecule would set up intermittent renewable energy to power fuel cells that would provide electricity on demand. The scalable production of H2 from splitting apart water (H2O), depends on how well the catalysts drive the reaction. Thus far, platinum catalysts are the best, but the metal’s scarcity and cost is problematic.
The microwave-prepared molybdenum disulfide material has the potential to be an affordable alternative to the expensive platinum catalysts that are currently used. The performance exceeds that of MoS2 materials made via other synthetic methods.
The blueprint for “the hydrogen (H2) economy” is to convert energy from renewable sources, such as sunlight or wind, and store it as chemical energy in the bonds of the H2 molecule by splitting water electrochemically. The energy then can be released in fuel cells on demand. The scalable production of H2 from water depends significantly on the performance of the catalysts that are needed in the electrochemical reaction. Thus far, platinum catalysts are the best performers, but their high cost and scarcity pose limitations to their widespread adoption.
This is another in an ever increasing line of new catalysts for hydrogen production in hopes of getting past the platinum cost barrier. Today’s very low fossil fuel prices has a dampener on development of new discoveries. But in not so many months that will come to an end and some strong effort will go into systems and processes that use some of these discoveries.
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