Precise structural assignment and controlled manipulation of single-atom active sites on solid state catalysts is critical to the development of next-generation energy conversion materials. Black phosphorus (bP), a layered 2D allotrope of phosphorus, is a particularly promising support as the lone pairs on each P atom are available to interact with metal centers. This work demonstrates the successful covalent functionalization of bP with catalytically relevant organometallic Re and Mo complexes and probes the structure of the resulting surface sites. The modified nanosheets feature discrete mononuclear organometallic fragments on the bP surface with no signs of nanoparticle formation or metal leaching. Ligands on the metal centers contain functional groups with spectroscopic tags (e.g. CO, BF4) to allow for characterization with a multitude of techniques including vibrational and X-ray photoelectron spectroscopies as well as powder X-ray diffraction. Carbonyl ligands on the functional groups coupled with infrared spectroscopy, Gaussian fitting, and DFT calculations allow the dominant M–bP binding mode of each material to be identified. As a proof-of-concept that the modified nanosheets are stable to transformations at the metal center, anion exchanges of Re(CO)3Cl-functionalized bP were performed. There are few reports of similar transformations on other materials, and no previous reports of these transformations on bP. Remarkably, new vibrational modes post-exchange clearly show successful transformation of the Re center, suggesting that the functionalized metal centers are available for traditional organometallic manipulation.

Surface functionalization of black phosphorus with discrete organometallic fragments

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.