Regulating Oxygen Vacancy Defects in Heterogeneous NiO-CeO_2−δ Hollow Multi-shelled Structure for Boosting Oxygen Evolution Reaction

CeO₂ with excellent oxygen storage-exchange capacity and NiO with excellent surface activity were used to construct a heterogeneous NiO-CeO_2−δ hollow multi-shelled structure (HoMS) by spray drying. It turned out that as the proportion of CeO₂ increases, the overpotential and Tafel slope of NiO-CeO_2−δ HoMSs first decreased and then increased. This is mainly because the construction of the NiO-CeO_2−δ HoMSs not only increases the specific surface area, but also introduces oxygen vacancy defects, thus improving the interface charge transfer capability of the materials and further improving the oxygen evolution reaction (OER) performance. However, the increase of the calcination temperature will induce the decay of the OER performance of NiO-CeO_2−δ HoMSs, which is mainly due to the decrease of the specific surface area, the reduction of oxygen vacancy defects, and the weakening of interface charge transfer capability. Furthermore, a series of heterogeneous composite HoMSs, such as Ni/Co, Mo/Ni, Al/Ni and Fe/Ni oxides was successfully constructed by spray drying, which enriched the diversity of HoMSs.