Ni2P nanoparticles (NPs) with different sizes were synthesized via thermal decomposition of single-source precursor.
The size of Ni2P NPs can easily be controlled by changing reaction temperature.
The smaller Ni2P NPs exhibit superparamagnetism and the larger Ni2P NPs exhibit ferromagnetic characteristic at 300 K.
The Ni2P NPs with small size exhibit higher electrocatalytic activity for the HER.
The magnetic and electrocatalytic properties of the Ni2P NPs are size-dependent.