Fabrication of NiC/MoC/NiMoO4 Heterostructured Nanorod Arrays as Stable Bifunctional Electrocatalysts for Efficient Overall Water Splitting.

Developing noble-metal-free, earth-abundant, highly active, and stable electrocatalysts with high efficiency for both hydrogen and oxygen evolution reactions is of great importance for the development of overall water-splitting devices, but still remains a challenging issue. Herein, a 3D heterostructured NiC/MoC/NiMoO4 electrocatalyst was prepared through a facile synthetic procedure. The electrocatalyst shows a superior catalytic activity and stability toward the hydrogen and oxygen evolution reactions. The optimized NiC/MoC/NiMoO4 catalyst presents low overpotentials of 68 and 280 mV to reach a current density of 10 mA cm-2 in 1.0 m KOH for the hydrogen and oxygen evolution reactions, respectively. Assembled as an electrolyzer for overall water splitting, such a heterostructure shows quite a low cell voltage of 1.52 V at 10 mA cm-2 and remarkable stability for more than 20 h. This work provides a facile but efficient approach for the design and preparation of highly efficient bifunctional and self-supported heterostructured electrocatalysts that can serve as promising candidates in electrochemical energy storage and conversion.