Molecular models representing a 2D heterostructure made of graphene (gray background hexagonal lattice), and islands on top of hexagonal WS2 and MoS, as well as an alloy of the two. Water (H2O) molecules in red (oxygen) and gray (hydrogen) come from the bottom left hand side and get transformed catalytically after interacting with the heterostructures into H2 bubbles (top right hand side). Credit: Penn State Materials Research Institute.
Platinum is a near perfect catalyst for splitting water molecules into hydrogen and oxygen. The only drawback is that it is very expensive. Researchers from Houston, Penn State and Florida State University claim to have found a cheaper replacement: Molybdenum disulfide (MoS2). A Swiss team already proposed this solution in 2011.
No efficiency numbers are given.
The Wiley link from 2016 mentions 12.4%
[phys.org] – Low cost, scalable water splitting fuels the future hydrogen economy
[phys.org] – Researchers report new, more efficient catalyst for water splitting
[pubs.rsc.org] – Amorphous MoS2 films as catalysts for electrochem. H2 prod. in H2O
[pubs.acs.org] – Amorphous Molybdenum Sulfides as Hydrogen Evolution Catalysts
[onlinelibrary.wiley.com] – MoS2 as a co-catalyst for photocatalytic hydrogen production from water
[wikipedia.org] – Molybdenum disulfide
[wikipedia.org] – Gibbs free energy