Ultrafast synthesis of Cu2O octahedrons inlaid in Ni foam for efficient alkaline water/seawater electrolysis.

[Display omitted] • An ultrafast method is developed to synthesize Cu 2 O octahedrons. • Highly dispersed Cu 2 O octahedrons inlaid in Ni Foam are obtained. • The sample displays superior catalytic activity in both alkaline water/seawater electrolytes. • The sample exhibits good catalytic durability and stability. Development of bifunctional cost-effective and self-supporting electrocatalysts for high-performance water/seawater electrolysis are vital for emerging energy storage and conversion technologies. Herein, an ultrafast strategy is reported to synthesis homogeneous Cu 2 O octahedrons inlaid in Ni foam (oct_Cu 2 O-NF) via spontaneous replacement of Ni with Cu, followed by rapid oxidization of Cu in air. Benefiting from the high dispersion of uniform octahedral structure and strong interaction between Cu 2 O and Ni foam, oct_Cu 2 O-NF displayed a superior activity for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) as well as outstanding stability. After assembling oct_Cu 2 O-NF as bifunctional electrodes for alkaline seawater splitting, the electrolyzer exhibited a very small cell voltage of 1.71 V to reach 10 mA cm−2. This brand-new way of ultrafast synthesis for oct_Cu 2 O-NF experimentally confirms the feasibility of Cu-based nanomaterials for efficient water/seawater electrolysis. [ABSTRACT FROM AUTHOR]