Single-crystalline CoFe nanoparticles encapsulated in N-doped carbon nanotubes as a bifunctional catalyst for water splitting

Single-crystalline CoFe alloy nanoparticles encapsulated in nitrogen-doped carbon nanotubes (CoFe@N-C) were synthesized through a simple heat-treatment in an N-2 environment. CoFe@N-C effectively catalyzed the overall water splitting in alkaline media. Specifically, the as-synthesized CoFe@N-C exhibited excellent activity towards the oxygen evolution reaction (OER) with a low over-potential of 292 mV at 10 mA cm(-2) and the hydrogen evolution reaction (HER) with a low overpotential of 110 mV at 10 mA cm(-2). The good electrocatalytic properties may be attributed to the synergistic electronic coupling between single-crystalline CoFe and highly conductive N-doped CNTs and the enrichment of active sites. Additionally, CoFe@N-C showed excellent stability and durability with no observable deviation in the overpotential for the OER and HER after 1000 cycles of cyclic voltammetry (CV).