Researchers at The University of Manchester have discovered that atomically thin micas are excellent proton conductors.
Atomically thin micas are commonly found in soil and could pose an important application in the use of 2D materials for fuel cells and other hydrogen-related technologies.
Researchers Professor Andre Geim and Dr Marcelo Lozada-Hidalgo of The University of Manchester have previously discovered that materials like graphene are highly permeable to protons, nuclei of hydrogen atoms. Alternatively, other 2D materials such as molybdenum sulphide (MoS2), which is just three atoms thick, is completely impermeable to protons. These findings resulted in researchers concluding that only one-atom thick crystals could be permeable to protons.
The new research from The University of Manchester shows that protons can permeate through few-layered micas despite micas being ten times thicker that graphene. When the layers of micas are isolated it increases the permeability, making the micas layer 100 times more permeable to the protons of graphene.
Lucas Mogg, a PhD student on the project and the first author of the paper said: “We found that proton conductivity in atomically-thin micas is 10 to 100 times higher than in graphene. It is encouraging because graphene is already being considered as a promising proton conducting material. Our results show micas could be even more promising – not least because they are abundant and inexpensive.”
Professor Andre Geim said: “The result also implies that many other 2D materials could be turned into proton conductors. Our strategy is not limited to protons or micas. Many more 2D crystals with atomic-scale channels similar to those in micas could be explored, hopefully bringing unexpected phenomena and new applications in the field of proton and ionic conductors.”
Dr Marcelo Lozada-Hidalgo said: “There is a lack of proton-conducting materials that can reliably operate between 100°C and 500°C. However, this is the sweet spot temperature range for optimum operation of fuel cells and other hydrogen technologies. Atomically-thin micas work rather well in this temperature range – they merit attention from this perspective.”