Transition metal atoms (TM = Sc, Ti, V, Cr, and Mn) decorated PBCF-graphene as a possible reversible hydrogen storage material: A DFT-D2 investigation

Abstract

One of the most pressing concerns for hydrogen energy development is the identification of new compounds with high capacity and effective reversibility for hydrogen storage. This study employs a unique all-sp2 hybridized two-dimensional (2D) carbon allotrope inspired by graphene synthesis using benzene as a precursor. This 2D carbon allotrope is a polybutadiene cyclooctatetraene framework known as PBCF-graphene. This work investigated the electrical and structural properties of transition metal-decorated PBCF-G (TM-PBCF-G) for H2 adsorption using the DFT-D2 technique. Next, the most stable structures' H2 uptake and storage were examined. According to the results, the hollow site in the hexagonal ring's center is the most stable location for all TM decorations. Additionally, PBCF-G which has been adorned with Sc and Ti has the highest energy stability, with Eb values of −7.599 and −8.380 eV, respectively. The analysis of H2's adsorption behavior on TM-PBCF-G indicates that Cr-PBCF-G has the greatest adsorption energies (−0.701 eV), and that H2's horizontal direction has a greater stability energy. Upon gradually adding more H2 molecules to pristine and Cr-PBCF-G, it is shown that these materials can store 4 and 17H2 molecules, respectively, with average adsorption energies of −0.102 and −0.167 eV/H2, and corresponding H2 storage capacities of 5.26 and 9.10 wt%. These results demonstrate the potential of Cr-PBCF-G as a viable H2 storage material in the future.