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.

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The aldehyde hydrogenation for stabilizing and upgrading biomass is typically performed in aqueous phase with supported metal catalysts. By combining density functional theory calculations and ab initio molecular dynamics simulations, the model reaction of formaldehyde hydrogenation with a Pt/TiO 2 catalyst is investigated with explicit solvent water molecules. In aqueous phase, both the O vacancy (Ov) on support and solvent molecules could donate charges to a Pt cluster, where the Ov could dominantly reduce the Pt cluster from positive to negative. During the formaldehyde hydrogenation, the water molecules could spontaneously protonate the O in the aldehyde group by acid/base exchange, generating the OH* at the metal−support interface by long-range proton transfer. By comparing the stoichiometric and reduced TiO 2 support, it is found that the further hydrogenation of OH* is hard on the positively charged Pt cluster over stoichiometric TiO 2 . However, with the presence of Ov on reduced support, the OH* hydrogenation could become not only exergonic but also kinetically more facile, which prohibits the catalyst from poisoning. This mechanism suggests that both the proton transfer from solvent water molecules and the easier OH* hydrogenation from Ov could synergistically promote aldehyde hydrogenation. That means, even for such simple hydrogenation in water, the catalytic mechanism could explicitly relate to all of the metal cluster, oxide support, and solvent waters. Considering the ubiquitous Ov defects in reducible oxide supports and the common aqueous environment, this synergistic effect may not be exclusive to Pt/TiO 2 , which can be crucial for supported metal catalysts in biomass conversion.

Designing an active and selective catalyst for nonoxidative conversion of methane under mild conditions is critical for natural gas utilization as a chemical feedstock. Here, we demonstrate that the origin of the selective nonoxidative conversion of methane by the titanium carbide supported nickel cluster arises from the formation of a nickel carbide site under the reaction conditions, which could stabilize the CH x intermediate to facilitate the C–C coupling, but further coking is rather limited. The reaction mechanism reveals that the C2 products can be formed via a key −CH x –CH3 intermediate. In addition, we demonstrate that boration of the nickel cluster site can improve the methane conversion toward C2 products. That higher activity and selectivity from the moderate rise in d orbital energy levels can therefore be considered as a descriptor of the catalyst effectiveness. These findings provide an understanding of the dynamic behavior of the single nickel cluster toward methane conversion to C2 products and guidance for their future rational design.