Hydrogen Confinement in Hexagonal Boron Nitride Bubbles Using UV Laser Illumination

Abstract

Hexagonal boron nitride (h‐BN) bubbles are of significant interest to micro‐scale hydrogen storage thanks to their ability to confine hydrogen gas molecules. Previous reports of h‐BN bubble creation from grown h‐BN films require electron beams under vacuum, making integrating with other experimental setups for hydrogen production impractical. Therefore, in this study, the formation of h‐BN bubbles is demonstrated in a 20 nm h‐BN film grown on a sapphire substrate with a 213 nm UV laser beam. Using atomic force microscopy, it is shown that longer illumination time induces larger h‐BN bubbles up to 20 µm with higher density. It is also demonstrated that h‐BN bubbles do not collapse for more than 6 months after their creation. The internal pressure and gravimetric storage capacity of h‐BN bubbles are reported. A maximum internal pressure of 41 MPa and a gravimetric storage capacity of 6% are obtained. These findings show that h‐BN bubbles can be a promising system for long‐term hydrogen storage.