Enhanced reversible hydrogen storage efficiency of zirconium‐decorated biphenylene monolayer: A computational study

Metal decorated carbon-containing two-dimensional monolayers have been explored as potential hydrogen storage materials because of their open structures which improve the storage capacity. Here, the H2 storage capability of the Zr-decorated biphenylene nanosheet is studied with the aid of first-principles calculations. Biphenylene is a recently synthesized ultra-flat material consisting of different-sized carbon rings. Zr atom interacts strongly with the monolayer with a binding energy of -4.79 eV due to charge transfer from Zr 3d orbital to C 2p orbital of biphenylene nanosheet. The hydrogen molecules bind to the Zr-decorated biphenylene monolayer with an average adsorption energy of -0.4 eV per H2 due to Kubas-type interactions involving charge transfer between metal d orbital and H 1s orbital. The Zr decoration helps to adsorb up to 9 hydrogen molecules per metal atom on the monolayer resulting in the H2 uptake of 9.95wt%, higher than the target of 6.5 wt% set by the Department of Energy(DoE), USA. The high diffusion barrier for the Zr atom prevents metal-metal clustering. The ab-initio molecular dynamics (AIMD) simulations show that the complexes remain stable even at the highest desorption temperature. The present study shows that the Zr-decorated biphenylene can be considered a prospective two-dimensional material for reversible hydrogen storage.