Bimetallic CoPt nanoparticles supported on shape-controlled La(OH)3 were synthesized by a one-step co-reduction synthetic process and used as a highly effective and magnetically recyclable catalyst for the selective decomposition of hydrous hydrazine.

Intermetallic catalysts are of immense interest, but how heterometals diffuse and related interface structure remain unclear when there exists a strong metal-support interaction. Here, we developed a kinetic diffusion–controlled method and synthesized intermetallic Pt 2 Mo nanocrystals with twin boundaries on mesoporous carbon (Pt 2 Mo/C). The formation of small-sized twinned intermetallic nanocrystals is associated with the strong Mo-C interaction–induced slow Mo diffusion and the heterogeneity of alloying, which is revealed by an in situ aberration-corrected transmission electron microscope (TEM) at high temperature. The twinned Pt 2 Mo/C constitutes a promising CO-resistant catalyst for highly selective hydrogenation of nitroarenes. Theoretical calculations and environmental TEM suggest that the weakened CO adsorption over Pt sites of Pt 2 Mo twin boundaries and their local region endows them with high CO resistance, selectivity, and reusability. The present strategy paves the way for tailoring the interface structure of high–melting point Mo/W-based intermetallic nanocrystals that proved to be important for the industrially viable reactions.

Tungsten and molybdenum carbides have shown great potential in catalysis and superconductivity. However, the synthesis of ultrathin W/Mo carbides with a controlled dimension and unique structure is still difficult. Here, inspired by the host−guest assembly strategy with single-walled carbon nanotubes (SWCNTs) as a transparent template, we reported the synthesis of ultrathin (0.8−2.0 nm) W 2 C and Mo 2 C nanowires confined in SWCNTs deriving from the encapsulated W/Mo polyoxometalate clusters. The atom-resolved electron microscope combined with spectroscopy and theoretical calculations revealed that the strong interaction between the highly carbophilic W/Mo and SWCNT resulted in the anisotropic growth of carbide nanowires along a specific crystal direction, accompanied by lattice strain and electron donation to the SWCNTs. The SWCNT template endowed carbides with resistance to H 2 O corrosion. Different from normal modification on the outer surface of SWCNTs, such M 2 C@SWCNTs (M = W, Mo) provided a delocalized and electron-enriched SWCNT surface to uniformly construct the negatively charged Pd catalyst, which was demonstrated to inhibit the formation of active PdH x hydride and thus achieve highly selective semihydrogenation of a series of alkynes. This work could provide a nondestructive way to design the electron-delocalized SWCNT surface and expand the methodology in synthesizing unusual 1D ultrathin carbophilic-metal nanowires (e.g., TaC, NbC, β-W) with precise control of the anisotropy in SWCNT arrays.

High-entropy alloys (HEAs) have drawn intensive interest in catalysis owing to their uniquely structured metal sites. However, the composition-dependent near-surface structure of HEAs, which is critical for regulating surface electronic structure and property, still remains unclear. Herein we reported a feasible wet-chemical strategy to synthesize quinary Pd x FeCoNiCu (Pd x -HEA) nanocrystals, which enabled the flexible control of Pd content (x = 2–27%) and the resultant tunable phase structure and size. The lattice expansion near surface increased with increasing heavy Pd atoms in Pd x -HEAs, which were quantitatively unveiled by aberration-corrected transmission electron microscopy. The semihydrogenation performance of alkynes to alkenes had a “volcano” plot in the dependence of Pd content in Pd x -HEAs. Among them, the Pd21-HEA catalyst exhibited the best performance for a series of alkynes, which was ascribed to the uniquely surrounding electronic environment around Pd induced by the strongest interaction (i.e., maximum electron transfer) between Co/Ni and Cu/Pd. This work demonstrated the importance of HEA composition-dependent lattice strain and the resultant surrounding electronic environment of Pd sites on the highly selective semihydrogenation.