Pt Single Atoms Embedded in the Surface of Ni Nanocrystals as Highly Active Catalysts for Selective Hydrogenation of Nitro Compounds

Abstract

Single-atom catalysts exhibit high selectivity in hydrogenation due to their isolated active sites, which ensure uniform adsorption configurations of substrate molecules. Compared with the achievement in catalytic selectivity, there is still a long way to go in exploiting the catalytic activity of single-atom catalysts. Herein, we developed highly active and selective catalysts in selective hydrogenation by embedding Pt single atoms in the surface of Ni nanocrystals (denoted as Pt₁/Ni nanocrystals). During the hydrogenation of 3-nitrostyrene, the TOF numbers based on surface Pt atoms of Pt₁/Ni nanocrystals reached ∼1800 h^–1 under 3 atm of H₂ at 40 °C, much higher than that of Pt single atoms supported on active carbon, TiO₂, SiO₂, and ZSM-5. Mechanistic studies reveal that the remarkable activity of Pt₁/Ni nanocrystals derived from sufficient hydrogen supply because of spontaneous dissociation of H₂ on both Pt and Ni atoms as well as facile diffusion of H atoms on Pt₁/Ni nanocrystals. Moreover, the ensemble composed of the Pt single atom and nearby Ni atoms in Pt₁/Ni nanocrystals leads to the adsorption configuration of 3-nitrostyrene favorable for the activation of nitro groups, accounting for the high selectivity for 3-vinylaniline