A new study shows that water confined in tiny spaces is not inherently more reactive than bulk water. Instead, high pressures that develop naturally inside the spaces explain most observed changes in chemistry.
Researchers used machine learning simulations to examine water trapped between sheets of graphene and hexagonal boron nitride. They found that van der Waals forces pull the sheets together, generating pressures of several gigapascals without any external force.
When systems were compared at the same chemical potential, the effect of confinement largely disappeared. Lead author Xavier R. Advincula said the confinement alone does not intrinsically change water's reactivity.
The surrounding material still matters. In droplets confined by hexagonal boron nitride, hydroxide ions bonded with the surface and increased dissociation. Graphene produced no such effect because of its inert chemistry.
The findings, published in Science Advances, offer a design principle for nanoscale devices. They could influence the development of batteries, fuel cells, and membranes by showing how to tune reactivity through pressure and surface interactions.
