▎ 摘　　要

Nickel sulfide (Ni3S2) is a promising electrocatalyst because of its good metal conductivity and stability in alkaline medium. However, the reported catalytic activity of Ni3S2 is still relatively low. N-doped graphene coated N-doped Ni3S2 nanocubes (N-Ni3S2 @NG) structure was proposed, which is an effective way to improve the catalytic activity of Ni3S2 . Thanks to the unique structural design and functional integration, the OER and HER in alkaline medium provide 238 mV and 100 mV over potential respectively at 10 mA cm(-2), and 1.53 V ultra-low operating voltage for overall water splitting. In addition, its super stable catalytic activity is also impressive, and the performance loss is negligible after 70 h durability test. These experimental data and analysis show that, the outstanding catalytic activity of N-Ni3S2 @NG is due to its abundant active centers and good electron transport properties. More broadly, this combination of bifunctional concept and nanoscale stereoscopic design is unique and advantageous, especially suitable for the development of highly active and durable electrocatalysts for energy conversion reactions. (C) 2021 Published by Elsevier Ltd.