Study on the Stability of CoxM3-xO4 (M = Ni, Mn and Ce) Nanowire Array Electrodes for Electrochemical Oxygen Evolution at Large Current Densities

Non-precious cobalt-based oxide nanoarrays with a doping of other metal ions have been reported as promising electrocatalysts for the oxygen evolution reaction (OER) of electrochemical water splitting. However, the influence of doped metal ions on their catalytic characteristic and inactivation mechanism for the OER at large current densities (> 500 mA cm−2) are rarely studied. Here, carbon fiber paper (CFP) possesses three-dimensional (3D) macroporous structure, excellent electrical performance and high stability, which is employed as the substrate material. Homogeneous CoxNi3-xO4, CoxMn3-xO4 and CoxCe3-xO4 nanowire arrays grown on CFP (CoNiO-NWs/CFP, CoMnO-NWs/CFP and CoCeO-NWs/CFP, respectively) are successfully fabricated by using the facile methods of hydrothermal synthesis and thermal decomposition. The CoNiO-NWs/CFP electrode at a current density of 1000 mA cm−2 achieve high OER stability of approximately 130 h, which is higher than that of clean Co3O4 nanowire array, CoMnO-NWs/CFP and CoCeO-NWs/CFP electrodes. The incorporation of the Ni in the spinel Co3O4 nanowires improves its electrocatalytic activity and long-term stability at large current densities. In contrast, the doping of the Mn and Ce to spinel Co3O4 nanowires has the opposite effect. This research shows that the inactivation mechanism of nanoarray electrodes for the OER of large current densities differs from traditional metal-oxide electrodes.