Enhanced storage capacity of hydrogen based on Li-decorated 2D BC6N under ambient conditions: First-principles study

Although two dimensional (2D) materials are good hydrogen storage materials, but they still cannot fulfill the necessary requirements of hydrogen storage under ambient conditions. Here we study Li atom decorated 2D BC6N for hydrogen storage under ambient conditions by employing first-principles calculations. Obtained results depict that original 2D BC6N can only adsorb 1H2 molecule with -0.207 eV/H2 adsorption energy. However, Li atom decoration enhances storage up to 4H2 with -0.252 eV/H2 adsorption energy. Later on, to check the maximum H2 adsorption capacity, we loaded 8Li atoms on 2D BC6N, and results of diffusion energy barrier of multiple Li atoms decorated 2D BC6N terminated the concerns of metal clustering at any point. One Li atom could adsorb 4H2 molecules and hence total 32H2 molecules were easily assimilated with -0.24 eV/H2 adsorption energy. We also calculated the relative energy as function of temperature and pressure individually to evaluate the thermodynamics of fully loaded system (32H2-8LiBC6N). The results exhibit that there is no problem of premature release of H2 molecules at room temperature at mild pressure, however H2 molecules start to release from 312 K. Gravimetric hydrogen density of ultimate system reached up to 8.7 wt% within USDOE directed kinetics. We propose that Li decorated 2D BC6N can be a realistic and enhanced capacity hydrogen storage material.