Metal-doped carbon nanocones as highly efficient catalysts for hydrogen storage: Nuclear quantum effect on hydrogen spillover mechanism

We investigated H-spillover mechanisms on Pt atoms decorating defective carbon nanocones (Pt/dCNC) using the multicomponent B3LYP (MC_B3LYP) method, which can take account of the nuclear quantum effect (NQE) of light nuclei. MC_B3LYP shows reduced relative energies for all stationary-point structures and lower energy barriers to H-spillover reactions. Interestingly, MC_B3LYP calculations reveal that the activation energy for H-2 dissociation completely vanishes indicating that H-2 molecules dissociate readily on Pt/dCNC. Our crucial finding is that the different metal (Pt and Pd) on dCNC surface has affected the thermodynamic favorability of the hydrogen dissociation process, on Pt/dCNC is facile and highly exothermic, while on Pd/dCNC is dramatically endothermic. Furthermore, comparison of combined dissociation-spillover mechanism on Pt decorated on carbon nanocone (Pt/dCNC) and Pt decorated on graphene (Pt/dG) catalysts have been focused to explain the curvature effect which can facilitate the hydrogen spillover process and provide a highly exothermic reaction, which is more thermodynamically favorable than that of a metal-graphene surface. Our new understanding of this reaction mechanism and the influence of NQEs on electronic properties will be useful for the future development of the spillover mechanism as well as the synthesis of high-performance Pt/dCNC for H-2 energy applications.

Automated summary

The study found that the hydrogen spillover process on Pt/dCNC is thermodynamically more favorable and the dissociation reaction is easier to occur, while it is dramatically endothermic on Pd/dCNC. Comparison between Pt/dCNC and Pt/dG catalysts indicated that the curvature effect can facilitate the hydrogen spillover process.