Black Phosphorus Surface Functionalization Towards Molecularly Defined Catalysts

Abstract

Black phosphorus (bP), a layered 2-dimensional allotrope of phosphorus, has emerged as apromising Van der Waals material for catalytic and electronic applications, in part due to its high surface area, layer dependent tunable bandgap, and its reactive basal plane. The bP surface serves as a chemical analog to molecular phosphines and may be functionalized to modify the surface reactivity and impart purpose-specific functional groups. Metallic centers are often used to decorate the surface of bP and impart catalytic activity at the metallic single sites. The synthesis of complex coordination environments on heterogenous catalysts promises a new generation of catalysts with high atom efficiency and tunability However, the coordination environment of single organometallic metal sites on the bP is rarely studied and the understanding of the functionalized surface remains underexplored. This work aims to further the understanding of the coordination environment of single metal sites on bP, introduce metallic sites with new binding modes onto bP, and probe enhanced catalytic activity from the functionalized bP nanosheets. Chapter 2 probes the dual functionalization of bP with two discrete metal environments on the surface, including the direct metal–phosphorus bonding of Re complexes to the surface and the tethered Re or Ru complexes through an organic o-quinone linker. Chapter 3 focuses on the functionalization of bP with group VI metal carbonyl complexes, which draws on the decades of research in both molecular phosphine chemistry and foundational surface organometallic chemistry performed on oxide supports. Here, the bP nanosheets are treated with molecular precursors to place highly dispersed metal (0) and metal oxide species on the surface. Spectroscopic ligands provide insights on the local binding environments and how they evolve under various conditions. Chapter 4 leverages the same synthetic techniques from earlier chapters to probe the coordination of multi-metallic Co6Se8L5 (L = PEt3, CO) clusters on the surface of bP. Here, we report one of the only examples of molecularly defined multi-metallic architectures on the surface of the bP nanosheets. The body of work presented herein establishes new techniques and provides novel insights into the surface organometallic chemistry of bP, positioning the material as a promising candidate for surface organometallic catalysis.