The initial stages of water adsorption on the Pd(111) and Ru(0001) surfaces have been investigated experimentally by Scanning Tunneling Microscopy in the temperature range between 40 K and 130 K, and theoretically with Density Functional Theory (DFT) total energy calculations and STM image simulations. Below 125 K water dissociation does not occur at any appreciable rate and only molecular films are formed. Film growth starts by the formation of flat hexamer clusters where the molecules bind to the metal substrate through the O-lone pair while making H-bonds with neighboring molecules. As coverage increases, larger networks of linked hexagons are formed with a honeycomb structure, which requires a fraction of the water molecules to have their molecular plane perpendicular to the metal surface with reduced water-metal interaction. Energy minimization favors the growth of networks with limited width. As additional water molecules adsorb on the surface they attach to the periphery of existing islands, where they interact only weakly with the metal substrate. These molecules hop along the periphery of the clusters at intermediate temperatures. At higher temperatures they bind to the metal to continue the honeycomb growth. The water-Ru interaction is significantly stronger than the water-Pd interaction, which is consistent with the greater degree of hydrogen-bonded network formation and reduced water-metal bonding observed on Pd relative to Ru.

Metal-and hydrogen-bonding competition during water absorption on Pd(111) and Ru(0001)

Stimulated by the recent fascinating finding of all-boron fullerene B40 (Zhai et al. in Nat Chem 6:727–731, 2014), we systematically investigated the structures, stabilities and electronic properties of its endohedral derivatives M@B40 (M = Sc, Y, La) by means of density functional theory computations. The binding energies of M@B40 are closely comparable with the classical M@C
 2v
 (9)–C82 family, suggesting the considerable possibility to experimentally achieve these endohedral borofullerenes. The paramagnetic M@B40 molecules can easily form stable dimers with quenched magnetism, which could be avoided by exohedral functionalization and promise potential applications in the design of nanodevices. Furthermore, the infrared absorption spectra and 11B nuclear magnetic resonance spectra were computed to assist future experimental characterization.

Computational investigation on the endohedral borofullerenes M@B 40 (M = Sc, Y, La)

Recent photoelectron spectroscopy and computational studies have shown that boron ring–centered transition metal–doped inverse sandwich complexes prefer planar or quasi-planar structures which could be a potential building blocks for designing better nanosystems with tailored properties. Due to promising technological applications of different boron nanoclusters, we present a study on the structural, electronic, magnetic, and spectroscopic properties of Co-centered inverted sandwich monocyclic boron nanoclusters with pyramidal, CoBn, and bi-pyramidal, Co2Bn (n = 6–8) shapes. The investigations have been carried out on previously reported stable hexa-, hepta-, and octagonal hole containing pyramidal and bi-pyramidal boron clusters by employing density functional theory calculations with B3LYP hybrid exchange-correlation functional. Our calculation suggests that all the global minima structures have stable planar or quasiplanar symmetrical cyclic motif. The structural stability of clusters has been investigated by analyzing binding energy, thermodynamical parameters, vibrational spectra etc. All parameters indicate that the bi-pyramidal structures (Co2B6, Co2B7, and Co2B8) are more stable than both pristine and singly doped boron nanoclusters. On the contrary, the bi-pyramidal cluster is chemically less stable than the pyramidal clusters (except CoB7) which is supported by the ionization potential, electron affinity, energy gap, and global indices calculations. Molecular electrostatic potential surface and HOMO-LUMO analysis have been carried out to understand the thermodynamically stable clusters that arises due to specific inter/intra-molecular interactions. The presence of magnetic element (Co) in the clusters induces ferromagnetic properties which have been found by investigating the magnetic moment, spin density, and DOS spectra analysis. Size and geometry-dependent properties of boron nanoclusters have been observed as evident from the energy gap and optical absorptions analysis.

A DFT study on the geometrical structures, electronic, and spectroscopic properties of inverse sandwich monocyclic boron nanoclusters ConBm (n = 1.2; m = 6–8)

Adsorption and interaction mechanisms of fullerene-based complex systems for possible drug delivery vehicles have been at the center of increasing attention. In the scope of this work, the interaction mechanism between an important antiviral drug favipiravir and silicon-doped/undoped C60 fullerenes have been investigated using density functional theory (DFT). Calculations were carried out in both gas phase and water media to see the possible solvent effects. The effect of adsorption of the favipiravir on the SiC59 fullerene system and the nature of interaction were examined by analyzing the band shifts in the carbonyl stretching vibrations and natural bond orbital (NBO) properties of the examined complexes. Some important structural and electronic properties were reported and discussed as well. It was observed that doping the C60 fullerene nanocages with silicon atom enhanced the adsorption mechanism and calculations performed in water media gave rise to more stable complexes for silicon-doped systems com...

Computational study on favipiravir adsorption onto undoped-and silicon-decorated C60 fullerenes

Two-dimensional optical catalysis materials have a wonderful potential application. Here, a new two-dimensional material consisting of the supported single-atom Au on a graphite carbon nitride (g-C3N4) single layer has been designed and its electronic and optical properties have been characterized by density functional calculations. The bandgap of 1.82eV calculated by the hybrid functional HSE06 shows that the Au/g-C3N4 is an indirect semiconductor, and the electron can easily be excited from the single-atom Au to the bottom of the conduction band. This material therefore has relatively strong optical properties in the visible region. Moreover, the process of Au insertion into the cavity of g-C3N4 single layer is energy-favorable. This work may provide insights and a new avenue for fabricating supported Au catalysts with high stability.

Theoretical investigation on the photocatalytic activity of the Au/g-C3N4 monolayer

Density functional theory calculations have been carried out to investigate 3d, Pd and Pt transition metal (TM) atoms exohedrally and endohedrally doped B80 fullerene. We find that the most preferred doping site of the TM atom gradually moves from the outer surface (TM = Sc), to the inner surface (TM = Ti and V) and the center (TM = Cr, Mn, Fe and Zn), then to the outer surface (TM = Co, Ni, Cu, Pd, and Pt) again with the TM atom varying from Sc to Pt. From the formation energy calculations, we find that doping TM atom can further improve the stability of B80 fullerene. The magnetic moments of doped V, Cr, Mn, Fe, Co and Ni atoms are reduced from their free-atom values and other TM atoms are completely quenched. Charge transfer and hybridization between 4s and 3d states of TM and 2s and 2p states of B were observed. The energy gaps of TM@B80 are usually smaller than that of the pure B80. Endohedrally doped B80 fullerene with two Mn and two Fe atoms were also considered, respectively. It is found that the antiferromagnetic (AFM) state is more energetically favorable than the ferromagnetic (FM) state for Mn2- and Fe2@B80. The Mn and Fe atoms carry the residual magnetic moments of ~ 3 μB and 2 μB in the AFM states.

Density functional theory study of transition metals doped B80 fullerene

Boosting Nitrogen Reduction to Ammonia on Fe-N3S sites by Introduction S into Defect Graphene

Multistep dissociative chemisorption reactions of water with Pd4 and Pd7 clusters were studied using density functional theory. The adsorption energies and referred adsorption sites from water molecule (H2O) to partially dissociative (H2+O and OH+H), then to fully dissociative (O+H+H) configurations are carefully determined. It is found that the adsorption energies of three dissociative reactions are 5–6 times larger than that of water molecule. Atop sites of Pd4 and Pd7 clusters are found to be the most stable sites for the adsorbed H2O molecule. For the coadsorption cases of partially and fully dissociated products, H2 and OH molecules preferably tend to bind at the low coordination (atop or bridge) sites, and O and H atoms prefer to adsorb on the high coordination (hollow) sites. It is also found that the most favorable adsorption sites for the molecular adsorbates (H2O, H2 and OH) are adjacent to the Pd atoms with the largest site-specific polarizabilities. Therefore, site-specific polarizability is a good predictor of the favorable adsorption sites for the weakly bound molecules. The different directions of charge transfer between the Pd clusters and the adsorbate(s) is observed. Furthermore, the processes of the adsorption, dissociation, and the dissociative products diffusion of H2O are analyzed.

Multistep reactions of water with small Pdn clusters: A first principles study

Structures and Magnetic Properties of Mo-Doped Palladium Clusters

Facile synthesis of graphene oxide-supported CoOx nanoparticles for efficient degradation of antibiotics via percarbonate activation: Performance, degradation pathway and mechanism

Yanhua Liang

Papers

Density functional theory study of transition metals doped B80 fullerene

Boosting Nitrogen Reduction to Ammonia on Fe-N3S sites by Introduction S into Defect Graphene

Multistep reactions of water with small Pdn clusters: A first principles study

Structures and Magnetic Properties of Mo-Doped Palladium Clusters

Facile synthesis of graphene oxide-supported CoOx nanoparticles for efficient degradation of antibiotics via percarbonate activation: Performance, degradation pathway and mechanism