We report that the Kondo effect exerted by a magnetic ion depends on its chemical environment. A cobalt phthalocyanine molecule adsorbed on an Au111 surface exhibited no Kondo effect. Cutting away eight hydrogen atoms from the molecule with voltage pulses from a scanning tunneling microscope tip allowed the four orbitals of this molecule to chemically bond to the gold substrate. The localized spin was recovered in this artificial molecular structure, and a clear Kondo resonance was observed near the Fermi surface. We attribute the high Kondo temperature (more than 200 kelvin) to the small on-site Coulomb repulsion and the large half-width of the hybridized d-level.
We demonstrate that BiOCl single-crystalline nanosheets possess surface structure-dependent molecular oxygen activation properties under UV light. The (001) surface of BiOCl prefers to reduce O2 to ·O2(-) through one-electron transfer, while the (010) surface favors the formation of O2(2-) via two-electron transfer, which is cogoverned by the surface atom exposure and the situ generated oxygen vacancy characteristics of the (001) and (010) surfaces under UV light irradiation.
A heterogeneous catalyst made of well-defined Co3 O4 hexagonal platelets with varied exposed facets is coupled with [Ru(bpy)3 ]Cl2 photosensitizers to effectively and efficiently reduce CO2 under visible-light irradiation. Systematic investigation based on both experiment and theory discloses that the exposed {112} facets are crucial for activating CO2 molecules, giving rise to significant enhancement of photocatalytic CO2 reduction efficiency.
Electronic structures of SiC nanoribbons have been studied by spin-polarized first-principles calculations. The armchair nanoribbons are nonmagnetic semiconductors, while the zigzag nanoribbons are magnetic metals. The spin polarization in the zigzag SiC nanoribbons is originated from the unpaired electrons localized on the ribbon edges. Interestingly, the zigzag nanoribbons narrower than ∼4 nm present half-metallic behavior. Without the aid of external field or chemical modification, the metal-free half-metallicity predicted for narrow SiC zigzag nanoribbons opens a facile way for nanomaterial-based spintronics applications.
The combination of gold and copper is a good way to pull down the cost of gold and ameliorate the instability of copper. Through shape control, the synergy of these two metals can be better exploited. Here, we report an aqueous phase route to the synthesis of pentacle gold–copper alloy nanocrystals with fivefold twinning, the size of which can be tuned in the range from 45 to 200 nm. The growth is found to start from a decahedral core, followed by protrusion of branches along twinning planes. Pentacle products display strong localized surface plasmon resonance peaks in the near-infrared region. Under irradiation by an 808-nm laser, 70-nm pentacle nanocrystals exhibit a notable photothermal effect to kill 4T1 murine breast tumours established on BALB/c mice. In addition, 70-nm pentacle nanocrystals show better catalytic activity than conventional citrate-coated 5-nm Au nanoparticles towards the reduction of p-nitrophenol to p-aminophenol by sodium borohydride.
Electronic structure, stability and non-linear optical properties of aza-fullerenes C60-2nN2n(n=1-12) AIP Advances 2, 042111 (2012) Laser-induced quantum pumping in graphene Appl. Phys. Lett. 101, 153506 (2012) External electric field induced oxygen-driven unzipping of carbon nanotubes J. Appl. Phys. 112, 074316 (2012) Flat bands near Fermi level of topological line defects on graphite
We report a first-principles study on the electronic structures of deformed graphene nanoribbons (GNRs). Our theoretical results show that the electronic properties of zigzag GNRs are not sensitive to uniaxial strain, while the energy gap modification of armchair GNRs (AGNRs) as a function of uniaxial strain displays a nonmonotonic relationship with a zigzag pattern. The subband spacings and spatial distributions of the AGNRs can be tuned by applying an external strain. Scanning tunneling microscopy dI/dV maps can be used to characterize the nature of the strain states, compressive or tensile, of AGNRs. In addition, we find that the nearest neighbor hopping integrals between pi-orbitals of carbon atoms are responsible for energy gap modification under uniaxial strain based on our tight binding approximation simulations.
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