We report a one-pot synthesis of atomically dispersed Ru on ultrathin Pd nanoribbons. By using synchrotron radiation photoemission spectroscopy (SRPES), extended X-ray absorption fine structure (EXAFS) measurements in combination with aberration corrected high-resolution transmission electron microscopy (HRTEM), we show that atomically dispersed Ru with content up to 5.9% was on the surface of the ultrathin nanoribbon. Furthermore, the ultrathin Pd/Ru nanoribbons could remarkably prohibited the hydrogenolysis in chemoselective hydrogenation of C=C bonds, leading to an excellent catalytic selectivity compared with the commercial Pd/C and Ru/C.

No abstract

First-principles investigations are performed on the stabilities and electronic and optical properties of SnSe 2(1−x) S 2x (x = 0.0625, 0.25, 0.5, 0.625, 0.8125, and 1.0) monolayer alloys by using density functional theory calculations. It is found that, above a critical temperature of 702 K, the mixing of SnSe 2 and SnS 2 is likely to form random alloys. The calculated negative substitution energy of S at the Se site of SnSe 2 suggests an alternative strategy for the synthesis of the alloys, i.e., by the substitution of S for Se in SnSe 2 monolayers. It is also shown that, due to the lattice mismatch and the pronounced charge transfer between SnSe 2 and SnS 2 , the band-gap values of the alloys deviate strongly from the concentration-averaged values of the constituents. Moreover, the dielectric functions of the alloys are determined to be anisotropic, with optical properties along the xy plane being more susceptible to the S content than those along the z direction, and the alloying enhances the absorption strength in the visible spectral region. We hope that these insights will be useful for future applications of SnSe 2(1−x) S 2x alloys.

The correlations between bulk/surface structure change and electrochemical kinetics of LiNi0.80Co0.15Al0.05O2 are systematically investigated at atomic level, including the initial charged, half-charged, and over-charged states. In the initial stage of charge, surface rearrangement occurs and an amorphous Li2CO3 layer forms on the surface, which can release stress and provide a stable interface. The Li2CO3 surface layer decomposes upon charging, resulting in decreased interface resistance for charge transfer. Meanwhile, the bulk structure goes through the two-phase reaction region toward the solid solution region, which demonstrates higher electrical conductivity and faster Li-ion mobility. Along with the charging process, more substantial surface rearrangement and the decomposed Li2CO3 layer lead to surface degradation. Together with the anisotropic volume change-induced mechanical stress, microcracks stem from the surface and provide access for electrolyte penetration. All of these cause high kinetic barriers for Li-ion extraction, as demonstrated by the high interface and charge-transfer resistance and slow lithium diffusion in this region.