The previous model on surface free energy has been extended to calculate size dependent thermodynamic properties (i.e., melting temperature, melting enthalpy, melting entropy, evaporation temperature, Curie temperature, Debye temperature and specific heat capacity) of nanoparticles. According to the quantitative calculation of size effects on the calculated thermodynamic properties, it is found that most thermodynamic properties of nanoparticles vary linearly with 1/D as a first approximation. In other words, the size dependent thermodynamic properties P(n) have the form of P(n) = P(b)(1 -K/D), in which P(b) is the corresponding bulk value and K is the material constant. This may be regarded as a scaling law for most of the size dependent thermodynamic properties for different materials. The present predictions are consistent literature values.

Water electrolysis shows great promise for the low-cost mass production of high-purity hydrogen. The relatively high dissociation energy of water, however, often results in rather sluggish kinetics of the hydrogen evolution reaction (HER) in alkaline conditions, even for the case of state-of-the-art Pt-based electrocatalysts.Here, we show the high efficiency of the hybrids of PtRu nanoclusters (NCs) and black phosphorus (BP) nanosheets in HER. Our PtRu NCs/BP electrocatalysts demonstrate a HER activity of 88.5 mA cm -2 at -70 mV in 1 M KOH, which is higher than that of commercial Pt/C by one order of magnitude. The observed extraordinarily high HER activity of the PtRu NCs/BP hybrids is interpreted in the framework of density functional theory. Theoretical modeling indicates that the electronic interaction between BP and PtRu NCs speeds up the dissociation of water and optimize the adsorption strength for H* species, giving rise to the remarkably high HER activity of the PtRu NCs/BP hybrids.

Cationic silver-doped silicon clusters, Si_nAg⁺ (n=6–15), are studied using infrared multiple photon dissociation in combination with density functional theory computations. Candidate structures are identified using a basin-hopping global optimizations method. Based on the comparison of experimental and calculated IR spectra for the identified low-energy isomers, structures are assigned. It is found that all investigated clusters have exohedral structures, that is, the Ag atom is located at the surface. This is a surprising result because many transition-metal dopant atoms have been shown to induce the formation of endohedral silicon clusters. The silicon framework of Si_nAg⁺ (n=7–9) has a pentagonal bipyramidal building block, whereas the larger Si_nAg⁺ (n=10–12, 14, 15) clusters have trigonal prism-based structures. On comparing the structures of Si_nAg⁺ with those of Si_nCu⁺ (for n=6–11) it is found that both Cu and Ag adsorb on a surface site of bare Si_n⁺ clusters. However, the Ag dopant atom takes a lower coordinated site and is more weakly bound to the Si_n⁺ framework than the Cu dopant atom

The structures of neutral cobalt-doped silicon clusters have been assigned by a combined experimental and theoretical study. Size-selective infrared spectra of neutral Si(n)Co (n = 10-12) clusters are measured using a tunable IR-UV two-color ionization scheme. The experimental infrared spectra are compared with calculated spectra of low-energy structures predicted at the B3P86 level of theory. It is shown that the Si(n)Co (n = 10-12) clusters have endohedral caged structures, where the silicon frameworks prefer double-layered structures encapsulating the Co atom. Electronic structure analysis indicates that the clusters are stabilized by an ionic interaction between the Co dopant atom and the silicon cage due to the charge transfer from the silicon valence sp orbitals to the cobalt 3d orbitals. Strong hybridization between the Co dopant atom and the silicon host quenches the local magnetic moment on the encapsulated Co atom.

Based on the rigorous consideration of the bond broken rule and surface relaxation, a model for the size-dependent surface free energy of face-centered-cubic nanoparticles and nanocavities is presented, where the surface relaxation is calculated by the BOLS relationship. It is found that the surface free energy of nanoparticles and nanocavities represents a reverse size effect-the surface free energy of nanoparticles decreases with the decrease of particle size while it rises with the shrinkage of cavities. The size effect on the surface free energy of nanoparticles and nanocavities is not evident in large size ranges, while it becomes more and more distinct with decreasing size, especially for sizes smaller than 10 nm. The present predictions are in good agreement with the available literature data.

The geometric structures of Si_nAu⁺ (n = 2–11, 14, and 15) clusters are investigated using density functional theory computations in combination with infrared multiple-photon dissociation spectra measured on the corresponding cluster·argon and cluster·xenon complexes. The Si_nAu⁺ clusters adopt planar structures for the smallest sizes (n = 2–4) and have three-dimensional geometries for larger sizes (n ≥ 5). All of the investigated Si_nAu⁺ clusters have exohedral structures in which the Au dopant atom is adsorbed on a surface site of the bare Si_n⁺ cluster at a low-coordinated position. The growth mechanism of Si_nAu⁺ clusters is discussed and compared with those of Si_nCu⁺ and Si_nAg⁺. The present results indicate that the filled d shell and the atomic radii of the dopant atoms may play important roles in the cage formation of the transition-metal-doped Si clusters. Moreover, it is found that the localization of charge on the Au dopant atoms in Si_nAu⁺ determines the extent of complex formation with argon and xenon

Combining two different layered structures to form van der Waals (vdW) heterostructure has recently emerged as an intriguing way of designing electronic and optoelectronic devices. Using first-principles calculation, the electronic and optoelectronic properties of the black phosphorus and MoS 2 (BP/MoS 2 ) heterostructure were investigated and the results give a theoretical explanation of the reported high photodetection responsivity. Linear dichroism and the carrier mobility of the heterostructure were calculated to be preserved compared to that of free BP. The carrier transport performance is expected to be enhanced in practical applications by the predicted synergistic effect. Our work demonstrates that by combing BP with monolayer MoS 2 , outstanding electronic and optoelectronic attributes can be achieved, which may shed light on the electronics and optoelectronics applications of the BP/MoS 2 heterostructure.

We report a simple, efficient method to prepare a Ti foam-based evaporator for efficient solar evaporation and desalination.