Active Co@CoO core/shell nanowire arrays as efficient electrocatalysts for hydrogen evolution reaction

Abstract

Exploration of high-efficiency non-noble-metal-based electrocatalysts towards Hydrogen evolution reaction (HER) is critical for water electrolysis. In this work, we adopt a facile hydrothermal deposition plus hydrogen reduction strategy to fabricate self-supported Co@CoO core/shell nanowire arrays as a high-performance electrocatalyst for HER. The Co@CoO nanowire arrays are firmly anchored on the nickel foam substrate, forming an integrated electrode with excellent stability. The formation mechanism of the unique Co@CoO core/shell nanowire arrays is also explored. By virtue of the superior intrinsic catalytic activity of CoO shell and excellent electrical conductivity of Co core, the Co@CoO electrode exhibits significantly promoted catalytic activity for HER with an ultra-low overpotential (76 mV at 10 mA cm-2) in alkaline solution, which is superior to almost all the reported CoO-based electrocatalysts. Moreover, the Co@CoO electrode also yields superior long-term durability without any significant performance degradation. DFT calculations further verify the underlying mechanisms. Our proposed optimization strategy sheds light on the development of high activity earth-abundant-metal-based electrocatalyst for hydrogen evolution.