One-step growth of Ni3Fe-Fe3C heterostructures well encapsulated in NCNTs as superior self-supported bifunctional electrocatalysts for overall water splitting

Ni 3 Fe-Fe 3 C heterostructures well encapsulated in N-doped carbon nanotubes (Ni 3 Fe-Fe 3 C@NCNTs) were fabricated by a facile one-step pyrolysis-growth approach. Thanks to the merits of abundant active sites, multiple heterogeneous interfaces, large electrochemical active surface area, robust structure, self-supporting configuration and remarkable synergistic effect, Ni 3 Fe-Fe 3 C@NCNTs exhibits excellent bifunctional catalytic activity and stability toward both HER and OER in alkaline media. Moreover, the Ni 3 Fe-Fe 3 C@NCNTs||Ni 3 Fe-Fe 3 C@NCNTs electrolyzer requires an ultralow voltage of 1.80 V for overall water splitting to reach a current density of 300 mA cm −2 , and it keeps stable over 300 h for continuous hydrogen generation with 100% Faradaic efficiency, surpassing Pt/C||RuO 2 electrolytic cell and showing great promise for industrial application in green hydrogen production.