Constructions of hierarchical nitrogen doped carbon nanotubes anchored on CoFe2O4 nanoflakes for efficient hydrogen evolution, oxygen evolution and oxygen reduction reaction

The three primary reactions in metal-air batteries and electrochemical hydrolysis are the hydrogen evolution reaction (HER), the oxygen evolution reaction (OER), and the oxygen reduction reaction (ORR). Therefore, it is crucial to develop efficient low-cost trifunctional catalysts. In this study, we design a self-supported electrocatalyst with hierarchical nanostructure, in which the bamboo-like nitrogen doped carbon nanotubes (NCNTs) encapsulated CoFe nanoparticles (CoFe NPs) in-situ anchored on nanoflower like CoFe2O4 via chemical vapor deposition. Strikingly, the resulting catalysts CoFe@NC/CoFe2O4/IF demonstrate exciting trifunctional catalytic performance, overpotential of 66 mV and 185 mV for HER and OER at current densities of 10 mA cm−2, and a half-wave potential of 0.852 V for ORR, respectively. In addition, the maximum power density of the Zinc-air batteries (ZABs) assembled with CoFe@NC/CoFe2O4/IF as the cathode electrode is 134.5 mW cm−2; and the overall water splitting requires only a voltage of 1.50 V at a decomposition current density at 10 mA cm−2. This method provides a new strategy for trifunctional electrocatalysts and offers a promising approach for self-driven water electrolysis devices.