Tip-welded Ternary FeCo2S4 Nanotube Arrays on Carbon Cloth as Binder-free Electrocatalysts for Highly Efficient Oxygen Evolution

In the quest for many sustainable energy conversion technologies such as water splitting and fuel cells, developing inexpensive yet highly efficient and robust electrocatalysts for oxygen evolution reaction (OER) is urgent but still an enormous challenge. Herein, tip-welded bimetallic iron-cobalt sulfide nanotube arrays with tunable morphology and composition were fabricated via a template-free method and directly grown on carbon cloth (FeCo2S4 NTA/CC) as a flexible binder-free catalytic electrode. Based on the well-defined hollow nanotube structure, more abundant active sites are exposed, which accelerates the charge transfer process. Benefited from the unique structure and synergistic effect of bimetallic sulfides, the obtained FeCo2S4 NTA/CC exhibits outstanding electrocatalytic activity toward OER with an extremely low overpotential of 317 mV to drive a current density of 100 mA cm−2, a small Tafel slope of 36 mV dec−1 and excellent durability during the alkaline water electrolysis in 1.0 M KOH.