LAUSR

Abstract Electrochemical water splitting is a facile and effective route to generate pure hydrogen and oxygen. However, the sluggish kinetics of hydrogen evolution reaction (HER) and especially oxygen evolution reaction (OER) hinder the water splitting efficiency. Meanwhile, the high-cost of noble-metal catalysts limit their actual application. It is thus highly urgent to exploit an economical and earth-abundant bifunctional HER and OER electrocatalyst to simplify procedure and reduce cost. Herein, we synthesize the three-dimensionally ordered macro-/mesoporous (3DOM/m) NixCo100-x alloys with distinctive structure and large surface area via a dual-templating technique. Among them, the 3DOM/m Ni61Co39 shows the lowest overpotentials of 121 mV and 241 mV at 10 mA/cm2 for HER and OER, respectively. Furthermore, when employed for water splitting, the Ni61Co39 only requires 1.60 V to approach 10 mA/cm2 and presents excellent stability. These encouraging performances of the Ni61Co39 render it a promising bifunctional catalyst for overall water splitting.