One stable electrocatalyst for two evolution reactions by one-pot combustion synthesis

Abstract

NiFeOx is a high-active electrocatalyst for oxygen evolution reaction (OER) in alkaline media, which gradually deactivate in the long run due to Fe loss from the active sites into media solution during electrocatalysis. Herein, we propose a promising stable CeNiFeOx electrocatalyst for oxygen and hydrogen evolution reactions (OER&HER) by a facile one-pot combustion synthesis. The X-ray diffraction (XRD) results indicate that both nickel and iron ions are successfully incorporated into ceria lattices to form a pure fluorite phase of CeNiFeOx nanopowders, indicating a new achievement of as high as 20% of Ni/Fe solubility in the ceria lattice for the first time. The electrochemical measurements indicate that CeNiFeOx exhibits the high OER activity of NiFeOx electrocatalyst and the enhanced stability of oxygen evolution electrocatalysts. The Ce0.8Ni0.15Fe0.05Ox with a single phase of cubic fluorite structure among all shows the most efficient activity with the overpotential of 325 mV for OER and 337 mV for HER at the current density of 10 mA cm−2 in 1 M KOH than the pure CeOx, NiFeOx and other CeNiFeOx nanoelectrocatalysts. After 1000 cycles, the Ce0.8Ni0.15Fe0.05Ox nano electrocatalyst exhibits the remarkably improved stability for OER compared to NiFeOx electrocatalyst. These findings demonstrate a facile approach to develop high-active and durable electrocatalysts under alkaline conditions for overall water splitting.