Hyperbranched Co₂P nanocrystals with 3D morphology for hydrogen generation in both alkaline and acidic media

Hyperbranched Co₂P nanocrystals with three-dimensional structure have successfully been synthesized by a facile one-step wet-chemical method. The hyperbranched Co₂P are consisted of a large number of nanofilaments. The crystal splitting should be responsible for the formation of this structure. Catalytic performances measurements toward hydrogen evolution reaction for the obtained hyperbranched Co₂P nanocrystals demonstrate a small overpotential of 100 mV at current density of 10 mA cm^-2, with a Tafel slope of 67 mV dec^-1 in 1 M KOH. Durability tests show that slight catalytic activity fading occurs after 2000 CV cycles or 22 h chronoamperometric testing. In addition, the hyperbranched Co₂P also perform well in 0.5 M H₂SO₄ with a low overpotential of 107 mV at 10 mA cm^-2 and a Tafel slope of 69 mV dec^-1. This facile method provides a strategy for the preparation of low-cost metal phosphide electrocatalysts for hydrogen evolution in both alkaline and acidic media.