Ultralow ruthenium loading Cobalt-molybdenum binary alloy as highly efficient and super-stable electrocatalyst for water splitting.

• A series of Ru-CoMo/CFP-# (# = 0, 1, 12, 24, 48 h) electrocatalysts were synthesized. • Ru-CoMo/CFP (24 h) demonstrated excellent HER and OER activity. • Ru loading can induce strong electron interactions and endow a better intrinsic activity. Searching for earth-abundant, highly efficient, and stable bifunctional electrocatalysts for water splitting is critical for the further development of sustainable energy generation, yet it remains a great challenge. Herein, a facile electrodeposition strategy followed by wet-chemistry treatment is reported for the fabrication of the ultralow amount loading of ruthenium (Ru) on CoMo alloy supported on carbon fiber paper (CFP) substrate (Ru-CoMo/CFP). Benefiting from the unique nano-architectures and synergetic effect of loading Ru material and CoMo alloy, the optimized Ru-CoMo/CFP exhibits excellent electrocatalytic activity and favourable stability toward electrochemical water splitting. The as-prepared Ru-CoMo/CFP composite exhibits a current density of 10 mA·cm−2 at overpotentials of 44 and 237 mV for catalyzing hydrogen and oxygen evolution reaction (HER/OER) in alkaline medium, respectively. The as-synthetized Ru-CoMo/CFP electrode is also demonstrated to function as anode and cathode, simultaneously, only needs a cell voltage of 1.54 V to yield 10 mA·cm−2, outperforming the state-of-the-art RuO 2 ||Pt/C couple (1.56 V). This work demonstrates substantial improvement in the design of high-efficiency electrodes for water electrolysis. [ABSTRACT FROM AUTHOR]