Aminophosphines as Precursors for Doped and Phase Pure Metal Phosphide Nanocrystals: Synthesis Beyond P(SiMe3)3

Abstract

Colloidal metal phosphide nanocrystals represent attractive synthetic targets for researchers. They exemplify the diversity of emergent properties presented by nanomaterials, as the class encompasses both semiconductors and metals. When quantum confinement is accounted for, nanoscale semiconducting metal phosphides have optical properties that span the visible and NIR range of the spectrum, making them suitable for a wide range of applications. The metallic transition metal phosphides are consistently touted as earth-abundant alternatives for the hydrogen evolution reaction with competitive catalytic activity, particularly in the form of high surface area nanoparticles. Transition metal phosphides are plagued by synthetic challenges. The reactions are either multistep with low yields, require high temperatures and extended reaction times, or produce mixtures of crystalline phases. While high quality syntheses of several semiconducting metal phosphides exist, many are either capable of only producing nanocrystals in one size or rely on incomplete reactions for size tunability. Recent and exciting work synthesizing indium phosphide from aminophosphines demonstrated precursor-dependent size control based on the indium halide. Prior to the work discussed here, this reactivity was only known for indium phosphide. Chapter 2 discusses our efforts broadening the scope of aminophosphine-based nanocrystal synthesis to include II-V materials and transition metal phosphides. After establishing this versatile platform for the synthesis of phase-pure metal phosphides, Chapter 3 highlights research done establishing aminophosphine-derived InP as a substrate for copper doping and spectroscopic analysis of surface treated materials.