Regulating the active species of Ni(OH)₂ using CeO₂: 3D CeO₂/Ni(OH)₂/carbon foam as an efficient electrode for the oxygen evolution reaction

Abstract

Three dimensional (3D) N, O and S doped carbon foam (NOSCF) is prepared as a substrate for <i>in situ</i> vertically grown Ni(OH)₂ nanosheets. As designed Ni(OH)₂/NOSCF possesses strong electrostatic interactions with OH^- ions due to many C[double bond, length as m-dash]O groups existing in NOSCF, which can facilitate the formation of crucial NiOOH intermediates during the OER process. CeO₂ nanoparticles (NPs) of ∼3.3 nm in size are decorated on Ni(OH)₂ nanosheets to design a highly efficient CeO₂/Ni(OH)₂/NOSCF electrocatalyst for the oxygen evolution reaction (OER). The CeO₂ NP decorated Ni(OH)₂/NOSCF not only exhibits a remarkably improved OER performance with an onset potential of 240 mV, outperforming most reported non-noble metal based OER electrocatalysts, but also possesses a small Tafel slope of 57 mV dec^-1 and excellent stability under different overpotentials. The synergistic effect of producing more active species of Ni^III/IV and accelerating the charge transfer for Ni(OH)₂/NOSCF by the introduction of CeO₂ NPs is also investigated. These results demonstrate the possibility of designing energy efficient OER catalysts with the assistance of earth abundant CeO₂-based catalysts.