DFT study of Pd4 and Pd3P supported on modified graphene for hydrogen storage

Abstract

In this study, density functional theory (DFT) calculations were utilized to investigate the feasibility of using Pd4 and Pd3P clusters for hydrogen adsorption and spillover, with a focus on their potential as hydrogen storage materials. Four different modified graphene slabs were examined and the results showed that pristine graphene (PG), phosphorus-doped pristine graphene (PPG), and phosphorus-doped single vacancy graphene (PSVG) are not suitable surfaces for decorating Pd4 and Pd3P clusters for hydrogen adsorption and spillover. Our results showed that Pd4/SVG and Pd3P/SVG materials exhibited high binding energies of −5.37 eV and −4.49 eV respectively, which indicated their potential to prevent desorption of Pd–H hydrides with H2 desorption. The stability of Pd4/SVG and Pd3P/SVG was also confirmed by molecular dynamics at a temperature of 500 K. Moreover, the decoration of Pd3P on SVG resulted in hydrogen adsorption with an average energy of 0.25 eV/H2, falling within the ideal useable range. At full saturation, the energy barrier for spillover decreased from 0.86 eV to 0.75 eV, and the system could store up to 5.74 wt% of hydrogen. Furthermore, the spillover reaction occurred rapidly at room temperature within 0.68 s. Our findings suggest that Pd3P decorated single vacancy graphene represents a promising hydrogen storage material, providing valuable insights into the development of effective hydrogen storage technologies.