Direct Visualization of Substitutional Li Doping in Supported Pt Nanoparticles and Their Ultra‐selective Catalytic Hydrogenation Performance

Abstract

It has only recently been established that doping light elements (lithium, boron, and carbon) into supported transition metals can fill interstitial sites, which can be observed by the expanded unit cell. As an example, interstitial lithium (intLi) can block H filling octahedral interstices of palladium metal lattice, which improves partial hydrogenation of alkynes to alkenes under hydrogen. In contrast, herein, we report intLi is not found in the case of Pt/C. Instead, we observe for the first time a direct ‘substitution’ of Pt with substitutional lithium (subLi) in alternating atomic columns using scanning transmission electron microscopy‐annular dark field (STEM‐ADF). This ordered substitutional doping results in a contraction of the unit cell as shown by high‐quality synchrotron X‐ray diffraction (SXRD). The electron donation of d‐band of Pt without higher orbital hybridizations by subLi offers an alternative way for ultra‐selectivity in catalytic hydrogenation of carbonyl compounds by suppressing the facile CO bond breakage that would form alcohols.