Triacylphosphines as a Novel Class of Phosphorus Sources for the Synthesis of Transition Metal Phosphide Nanoparticles.

Transition metal phosphide (TMP) nanoparticles (NPs) are versatile materials for energy conversion/storage applications due to their robustness and many possibilities to tailor NPs' electronic, physical, and chemical properties. One of the hurdles toward their broader implementation is their challenging synthesis exacerbated by the limited choice of phosphorus precursors. On the one hand, the synthesis of TMP NPs can employ various alkyl- or arylphosphines requiring prolonged heating at high temperatures, while on the other hand, highly reactive P(SiMe), white phosphorus, or PH pose additional obstacles associated with their hazardous nature, high cost, and limited availability. This work introduces the use of acylphosphines as a new class of phosphorus sources for synthesizing phosphide NPs. They are shown to react with respective metal chlorides at moderate temperatures as low as 250 °C yielding poorly crystalline NPs, which can later be crystallized at 305 °C. After ligand stripping with HPF, NPs are found to be an effective electrocatalyst for the hydrogen evolution reaction in the acidic medium exhibiting overpotentials as low as 50 mV at a current density of 10 mA cm, which is among the lowest overpotentials for these materials and is quite competitive to commercial platinum-based catalysts.