Single-layer cadmium chalcogenides: promising visible-light driven photocatalysts for water splitting.

Recently, various single-layer materials have been explored as desirable photocatalyts for water splitting. In this work, based on extensive density functional theory calculations, we examine the geometric, electronic, optical, and potential photocatalytic properties of single-layer cadmium chalcogenides (CdX sheets, X = S, Se, and Te), which are cleaved from the (001) plane of the bulk wurtzite structure. The predicted formation energies have relatively low values and a suitable substrate (i.e. graphene) that can effectively stabilize CdX sheets, which imply that the fabrication and application of CdX sheets are highly possible in experiments. The calculated band gaps, band edge positions and optical absorptions clearly reveal that CdSe and CdTe sheets are promising photocatalysts for water splitting driven by visible light. Moreover, the band gaps and band edge positions of three CdX sheets can be effectively tuned by applying biaxial strain, which then can enhance their photocatalytic performance. These theoretical findings imply that CdX sheets are promising candidates for photocatalytic water splitting.

Facile synthesis of pentacle gold-copper alloy nanocrystals and their plasmonic and catalytic properties.

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.

Iron-phthalocyanine molecular junction with high spin filter efficiency and negative differential resistance.

We investigate the spin transport properties of iron-phthalocyanine (FePc) molecule sandwiched between two N-doped graphene nanoribbons (GNRs) based on the density functional theory and nonequilibrium Green's function methods. Our calculated results clearly reveal that the FePc molecular junction has high spin-filter efficiency as well as negative differential resistance (NDR). The zero-bias conductance through FePc molecule is dominated by the spin-down electrons, and the observed NDR originates from the bias-dependent effective coupling between the FePc molecular orbitals and the narrow density of states of electrodes. The remarkable high spin-filter efficiency and NDR are robust regardless of the edge shape and the width of GNRs, and the N-doping site in GNRs. These predictions indicate that FePc junction holds great promise in molecular electronics and spintronics applications.