Modulating geometric, electronic, gas sensing and catalytic properties of single-atom Pd supported on divacancy and N-doped graphene sheets

Abstract

The formation geometries, gas sensing and catalytic properties of single Pd atom supported on divacancy graphene (555-777-graphene-Pd) and Nx-doped graphene (Nx-graphene-Pd, x = 1, 2, 3) are systemically investigated using the first-principle calculations. Compared with 555-777-graphene-Pd, the formation of Nx-graphene-Pd configurations have the smaller formation energies and the N3-graphene-Pd is more easily formed than other ones. The N3-graphene-Pd substrate exhibits the higher adsorption sensitivity for detecting gas reactants than that on 555-777-graphene-Pd. Besides, the single gas molecule and two coadsorbed gas molecules can control the electronic structures and magnetic properties of single-atom Pd anchored graphene systems. In the sequential oxidation reactions for NO and CO, the termolecular Eley–Rideal (TER) reaction as initial state has the relatively lower energy barriers (<0.2 eV) on N3-graphene-Pd than that of Eley–Rideal (ER) and Langmuir–Hinshelwood (LH) mechanisms. Moreover, these oxidation reactions (TER, ER and LH) through the rate-limiting steps have the small energy barriers (<0.7 eV), which demonstrates that the doped Pd and N atoms within graphene may be an efficient catalyst for toxic gases removal.