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We use hybrid density functional calculations to find that the monolayer silicane (SiH) and the anatase TiO2(101) composite (i.e. the SiH/TiO2 heterojunction) is a promising TiO2-based photocatalyst under visible light. The band gap of the SiH/TiO2(101) heterojunction is 2.082 eV, which is an ideal material for the visible-light photoexcitation of electron-hole pairs. Furthermore, the SiH/TiO2(101) heterojunction has a favorable type-II band alignment and thus the photoexcited electron can be injected to the conduction band of anatase TiO2 from that of silicane. Finally, the proper interface charge distribution facilitates the carrier separation in the SiH/TiO2(101) interface region. The electron injection and carrier separation can prevent the recombination of electron-hole pairs. Our calculation results suggest that such electronic structure of SiH/TiO2(101) heterojunction has significant advantages over these of doped TiO2 systems for visible-light photocatalysis. [ABSTRACT FROM AUTHOR]

PdAg bimetallic and PdAgCo trimetallic nanoparticles (NPs) are synthesized by a one-pot method in an organic solvent medium. Our results show that the catalytic activity of PdAgCo/C (1133.249mA mgPd-1) for formic acid oxidation (FAO) is ca. 2.4 times larger than commercial Pd/C (483.563mA mgPd-1) and 1.7 times larger than PdAg/C (680.741mA mgPd-1). This study indicates that Co doping in PdAg bimetallic NPs can significantly improve its FAO activity. It is expected that the as-synthesized PdAgCo trimetallic NPs could be used as high-performance catalysts for direct formic acid fuel cells (DFAFCs). [ABSTRACT FROM AUTHOR]

The onion-ring structure is validated in the Pd−Pt bimetallic clusters of total atom numbers 147 and 309 through the Monte Carlo method by using the second-moment approximation of the tight-binding (TB-SMA) potentials, which is conceived in predicting the possible structures of the bimetallic clusters by He et al. J. Am. Chem. Soc.2003, 125, 11034 and Hwang et al. J. Am. Chem. Soc.2005, 127, 11140. In the onion-ring structure, Pd atoms and Pt atoms occupy alternate layers of the clusters. The formation of the onion-ring structure can be associated with the fact that the single Pt impurity is favorable to stay in the subsurface layer and the central part of bimetallic clusters. [ABSTRACT FROM AUTHOR]

A facile one-pot method for synthesizing different morphologies of PdCu nanocrystals (NCs) has been introduced. The morphologies of PdCu NCs can be controlled by tuning the amount of the single capping ligand of triphenylphosphine (TPP) in an organic solvent medium. Highly structured cubic, sphere, and sphere-like PdCu NCs were obtained in a sufficient amount, a small amount, and the absence of TPP, respectively. It is found that these PdCu NCs exhibit efficient catalytic activities for formic acid oxidation (FAO). The mass activities of these carbon-supported NCs follow the order of sphere PdCu/C > sphere-like PdCu/C > cubic PdCu/C at a potential of 0.2V (vs. SCE). Among these NCs, the sphere PdCu/C catalyst exhibits the highest FAO activity, which is 1.7 times larger than that of commercial Pd/C catalyst at 0.2V. Our results show that the surfactant loading can play a key role in the shape-controlled synthesis of PdCu nanocrystals for FAO. [ABSTRACT FROM AUTHOR]

In order to combine the advantages of both 0D and 1D nanostructured materials into a single catalyst, density functional theory (DFT) calculations have been used to study the PdCu alloy NP-decorated Cu nanotubes (PdCu@CuNTs). These present a significant improvement of the electrocatalytic activity of formic acid oxidation (FAO). Motivated by our theoretical work, we adopted the seed-mediated growth method to successfully synthesize the nanostructured PdCu@CuNTs. The new catalysts triple the catalytic activity for FAO, compared with commercial Pd/C. In summary, our work provides a new strategy for the DFT prediction and experimental synthesis of novel metal NP-decorated 1D nanostructures as electrocatalysts for fuel cells. [ABSTRACT FROM AUTHOR]

Understanding the phase diagram is the first step to identifying the structure–performance relationship of a material at the nanoscale. In this work, a modified nanothermodynamical model has been developed to predict the phase diagrams of Ag–Co nanoalloys with the size of 1 ∼ 100 nm, which also overcomes the difference in the predicted results between theory and simulation for the first time. Based on this modified model, the phase diagrams of Ag–Co nanoalloys with various polyhedral morphologies (tetrahedron, cube, octahedron, decahedron, dodecahedron, rhombic dodecahedron, truncated octahedron, cuboctahedron, and icosahedron) have been predicted, showing good agreement with molecular dynamics simulations at the nanoscale of 1 ∼ 4 nm. In addition, the surface segregation of Ag–Co nanoalloys has been predicted with a Co-rich core/Ag-rich surface, which is also consistent with the simulation results. Our results highlight a useful roadmap for bridging the difference between theory and simulation in the prediction of the phase diagram at the nanoscale, which will help both theorists and experimentalists. [ABSTRACT FROM AUTHOR]