Mo 2 C@C nanofibers film as durable self-supported electrode for efficient electrocatalytic hydrogen evolution.

Self-supported electrocatalytic thin films consist 3D conducting network and well-embedded electrocatalysts, which endows the advantage in mass flow kinetics and durability for large-scale water splitting. Synthesis of such self-supported electrode still remains a big challenge due to the difficulty in the control over the 3D conducting network and the simultaneous growth of catalyst with well attachment on the conducting fibers. Herein, a self-supported Mo 2 C@carbon nanofibers (Mo 2 C@C NF) film has been successfully fabricated with outstanding electrocatalytic performance under optimized pyrolysis temperature and precursors mass ratio conditions. During the carbonation process, the Mo 2 C nanoparticles ( ∼ 16 nm) were simultaneously grown and well dispersed on the inter-connected carbon nanofibers, which formed a 3D conducting network. The as-formed 3D carbon network was strong enough to support direct electrocatalytic application without additional ink or supporting substrates. This particular electrode structure facilitated easy access to the active catalytic sites, electron transfer, and hydrogen diffusion, resulting in the high hydrogen evolution reaction activity. A low overpotential of 86 mV was needed to achieve 10 mA cm -2 current density with outstanding kinetics metric (Tafel 43 mV dec -1 ) in 1 M KOH. Additionally, the self-supported Mo 2 C@C NF film, a binder-free electrode, exhibited extraordinary stability of more than 340 h.