Hyperbranched Co 2 P nanocrystals with 3D morphology for hydrogen generation in both alkaline and acidic media.

Hyperbranched Co 2 P nanocrystals with three-dimensional structure have successfully been synthesized by a facile one-step wet-chemical method. The hyperbranched Co 2 P 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 Co 2 P 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 Co 2 P also perform well in 0.5 M H 2 SO 4 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.