MoP can be synthesized by hydrothermal method followed by phosphidation. Direct synthesis by one-step hydrothermal or solvothermal reaction is rarely reported.

Rajalakshmi Rajendran

Molybdenum phosphide, MoP, can be synthesized directly from the elements at temperatures between 600 and 1100 °C:

http://actachemscand.org/pdf/acta_vol_17_p0037-0046.pdf

Apparently, an easier way of preparing this material is the thermal reaction of a solid mixture containing (NH4)4Mo7O24·2H2O, (NH4)2HPO4 and hexamethylenetetramine under argon:

Article A new approach to the synthesis of molybdenum phosphide via ...