Black Phosphorus/Palladium Nanohybrid: Unraveling the Nature of P-Pd Interaction and Application in Selective Hydrogenation

TL;DR

This study develops a novel black phosphorus/palladium nanohybrid catalyst with unique Pd-P covalent bonds, demonstrating enhanced stability and superior selectivity in hydrogenation reactions of chloronitroarenes.

Contribution

It uncovers the covalent Pd-P interaction in bP-supported Pd nanoparticles and demonstrates improved catalytic performance and stability in hydrogenation.

Findings

Discovery of covalent Pd-P bonds with 2.26 Å distance.

bP acts as a polydentate ligand, stabilizing Pd nanoparticles.

Enhanced chemoselectivity in hydrogenation of chloronitroarenes.

Abstract

The burgeoning interest in 2D black phosphorus (bP) contributes to expand its applications in countless fields. In the present study, 2D bP is used as a support for homogeneously dispersed palladium nanoparticles directly grown on it by a wet chemical process. EELS-STEM analysis evidences a strong interaction between palladium and P atoms of bP nanosheets. A quantitative evaluation of this interaction comes from XAS measurements that find out a very short Pd-P distance of 2.26 {\AA} proving for the first time the existence of an unprecedented Pd-P coordination bond of covalent nature. Additionally, the average Pd-P coordination number of about 1.7 reveals that bP acts as a polydentate phosphine ligand towards the surface Pd atoms of the nanoparticles, thus preventing their agglomeration and inferring structural stability. These unique properties result in a superior performance in the catalytic hydrogenation of chloronitroarenes to chloroaniline, where a higher chemoselectivity in comparison to other heterogeneous catalyst based on palladium has been observed.