  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.
