Rapid construction of Co/CoO/CoCH nanowire core/shell arrays for highly efficient hydrogen evolution reaction.

The Co/CoO/CoCH (P-CoCH) nanowire core/shell arrays were prepared by a one step hydrothermal method and rapid reduction of cobalt carbonate hydroxide (CoCH) in Ar/H 2 plasma for the first time. The rapid reduction process endows the P-CoCH with a unique porous structure, larger electrochemical active surface area and abundant activity sites. Therefore, the as-prepared P-CoCH nanowire core/shell arrays show superior HER performance with a low overpotential of 69 mV and a small Tafel slope of 47 mV dec -1 at a current density of 10 mA cm -2 . In addition, the P-CoCH electrocatalyst demonstrates an excellent cycling stability without any obvious decay after 24 h continuous operation at 100 mA cm -2 current density. This study might provide a new insight into the rapidly construction of efficient HER Co-based electrocatalysts and beyond.