Hydrogen adsorption and dissociation on Pd19 cluster using density functional calculations

H2 adsorption and dissociation on Pd19 cluster was studied using density functional theory with GGA-PW91 exchange–correlation functional. The stable configuration shows that H2 prefers to be adsorbed on 5-coordinated top site. LUMO of H2 and HOMO of Pd19 cluster are matched with the largest overlap on the top site. On face site, suitable initial adsorption configuration will lead to H2 dissociation into two atoms without barrier. On top site, the dissociation and diffusion processes need to overcome energy barrier of respective 0.304 and 0.224 eV. Adsorption exothermic heat help overcome H2 dissociation energy barrier on top site. The detailed analysis of frontier orbitals and Hirshfeld charge show the charge transfer from the Pd atom to the antibonding orbital of H2 is associated with the breaking of the H–H bond. DOS shows an isolated peak occur due to the contribution of H1s orbital for dissociative Pd19H2.