Polylithiated Species-Decorated Two-Dimensional Polyaniline (C₃N) Monolayer: A Promising Hydrogen Storage Medium

Exploring optimization strategies for enhancing the hydrogen storage performance of nanomaterials with a high specific surface area is crucial for developing their hydrogen storage potential. Here, we conducted first-principles calculations and ab initio molecular dynamics (AIMD) simulations to investigate the geometric structure and thermal stability of CLi3, NLi4, and OLi3 cluster-decorated C3N monolayers. The results indicate that only the CLi3 cluster can be stably anchored on the substrate as cluster unit. Investigations into the electronic structure of the CLi3 cluster-decorated C3N monolayer reveal that a covalent interaction is formed between the C atoms of the CLi3 cluster and the C3N substrate. The CLi3 cluster on the C3N substrate exhibits a cationic state, providing abundant adsorption sites for hydrogen uptake. The study on hydrogen storage performance demonstrates that a 2 × 2 × 1 C3N supercell decorated by the CLi3 cluster on both sides can capture 18 H2 molecules, achieving a high gravimetric hydrogen density of 7.23 wt %, surpassing the target established by the U.S. Department of Energy (DOE). The moderate adsorption energy of −0.21 eV/H2 is within the ideal window of the adsorption strength. The evaluation of the dependence of temperature and pressure on hydrogen storage performance indicates that the hydrogen-adsorbed systems are stable and achieve high reversible hydrogen storage capacity under mild conditions. The present findings suggest that the CLi3 cluster-decorated C3N monolayer may serve as a potential candidate for efficient hydrogen storage, providing valuable insights into the understanding of the adsorption mechanisms of polylithiated species-decorated monolayers.