The development of low-cost and high-efficiency catalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline electrolyte is still challenging. Herein, interfacial Co/CoMoN heterostructures supported on Ni foam (Co/CoMoN/NF) are constructed by thermal ammonolysis of CoMoOx . In 1.0 m KOH solution, Co/CoMoN/NF heterostructures exhibit excellent HER activity with an overpotential of 173 mV at 100 mA cm-2 and a Tafel slope of 68.9 mV dec-1 . Density functional theory calculations indicate that the low valence state Co site acts as efficient water-dissociation promoter, while CoMoN substrate has favorable hydrogen adsorption energy, leading to an enhanced HER activity. The Co/CoMoN/NF heterostructures also achieve high OER activity with an overpotential of 303 mV at 100 mA cm-2 and a Tafel slope of 56 mV dec-1 . Using Co/CoMoN/NF heterostructures as the cathode and anode, the alkaline electrolyzer requires a low voltage of 1.56 V to reach the current density of 100 mA cm-2 along with superior long-term durability. This study provides a new design strategy toward low-cost and excellent catalysts for water splitting.
Keywords: heterostructures; hydrogen evolution reaction; interface engineering; overall water splitting; oxygen evolution reaction.
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