A comprehensive approach for doping selection and assessment in porous materials for hydrogen storage: CNTs study case

Identifying a nanostructure suitable for hydrogen storage presents a promising avenue for the secure and cost-effective utilization of hydrogen as a green energy source. This study introduces a systematic approach for selecting optimal doping on porous materials, emphasizing the intricate interplay between doping with the material's structure and the interaction between doping and hydrogen. Our proposed approach serves as a framework for evaluating and predicting the performance of doped materials. To validate the efficacy of our strategy, we conduct a comprehensive investigation in carbon nanotubes (CNTs). Applying our criteria, we systematically screen several dopants in CNTs. The results highlight Cu-doped CNTs as promising candidates for hydrogen storage applications. Focusing on Cu-doped CNTs, we analyze binding energy, charge transfer, partial density of states (PDOS), and desorption temperature to assess the performance of modified CNTs. Additionally, we explore the feasibility of doped CNTs featuring various sizes of copper clusters and the effect on the release temperature, i.e., complete regeneration. The findings indicate that incorporating 5 to 6% copper impurity onto CNT surfaces renders these nanostructures highly applicable for reversible hydrogen storage near ambient conditions.