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Ti 2 Cu, TiCu and TiCu 4 were synthesized and their electrocatalytic activities for hydrogen evolution reaction (HER) were investigated. The hydrogen overpotential observed at 10 mA/ cm2 (η 10) followed the order Ti 2 Cu (η 10 = −215 mV) > TiCu (η 10 = −182 mV) > TiCu 4 (η 10 = −170 mV). The hydrogen adsorption energy (∆G Had) on Cu site of TiCu 4 is exergonic and close to optimal position (i.e. ∆G Had = 0). A synergistic effect was proposed to account for the excellent HER performance of these Ti Cu binary intermetallics compounds that could replace PGM and achieve Midas touch in the future. [Display omitted] • High purity of Ti 2 Cu, TiCu and TiCu 4 were synthesized by using rapid arc-melting technique. • Hydrogen evolution reaction (HER) study on Ti 2 Cu, TiCu and TiCu 4 in alkaline media. • HER activity of Ti 2 Cu, TiCu and TiCu 4 were explored by using density functional theory. • Synergistic effect for these Ti Cu binary intermetallics toward HER activity was discussed. [ABSTRACT FROM AUTHOR]

The Mn-Bi-Te class of compounds are recently discovered topological insulators with broken time-reversal-symmetry, which host unique quantum anomalous Hall and axion insulator states. Their key characteristics are believed to be sufficiently understood by models in a single-particle picture. Here, we apply scanning tunneling microscopy to study the electronic properties of MnBi2Te4 and MnBi4Te7. Unexpectedly, our quasiparticle interference (QPI) results demonstrate that rotational symmetry of the crystal breaks, i.e. a nematic-like pattern arises, in certain energy range but persists in others. Moreover, our data in the presence of an external magnetic field rule out the possibility of the material magnetism as an origin of the C2 symmetric QPI pattern. This study reveals that the interaction in the Mn-Bi-Te class of topological materials may play an essential role in their electronic states, and thus opens a new path for investigating the interplay between wavefunction topology and symmetry breaking phases. [ABSTRACT FROM AUTHOR]

We have fabricated ultra-thin lead films on silicon substrates with atomic-scale control of the thickness over a macroscopic area. We observed oscillatory behavior of the superconducting transition temperature when the film thickness was increased by one atomic layer at a time. This oscillating behavior was shown to be a manifestation of the Fabry-Pérot interference modes of electron de Broglie waves (quantum well states) in the films, which modulate the electron density of states near the Fermi level and the electronphonon coupling, which are the two factors that control superconductivity transitions. This result suggests the possibility of modifying superconductivity and other physical properties of a thin film by exploiting well-controlled and thickness-dependent quantum size effects. [ABSTRACT FROM AUTHOR]

Silicene, a monolayer of silicon atoms arranged in honeycomb lattices, can be synthesized on the Ag(111) surface, where it forms several superstructures with different buckling patterns and periodicity. Using scanning tunneling microscopy (STM), we obtained high-resolution images of silicene grown on Ag(111) and revealed its five phases, i.e., 4 × 4 − α, 4 × 4 − β, − α, − β and − γ, some observed for the first time. For each of the phases, we have determined its atomic structure by comparing the atomic-resolution STM images with theoretical simulation results previously reported. We thus eliminate the contradictions of previous studies on the structural models of various silicene phases supported by the Ag(111) surface. [ABSTRACT FROM AUTHOR]