Nd and Ni Co-doped spinel Co3O4 nanosheet as an effective electrocatalyst for oxygen evolution reaction

It is well known that the regulation of active sites in tetrahedrons (Td) and octahedrons (Oh) can improve the electrocatalytic performance of the spinel oxides (AB2O4) type materials when used for oxygen evolution reaction (OER). However, the effect of site modulation on the surface reconstruction in electrocatalyst is still not clear during the OER process. In this work, NdNi-Co3O4 was prepared by introducing Ni2+ and Nd3+ into Co3O4, which exhibited an excellent activity with an overpotential of 269 mV at 10 mA·cm−2 and a Tafel slope of 54 mV·dec−1. In-situ Raman spectroscopy showed that the catalyst surface apparently underwent a reconstruction process with the generation of cobalt hydroxyl oxides (CoOOH) after Ni-substitution, and the further introduction of Nd led to the formation of CoOOH at lower potential. DFT calculations revealed that the introduction of Ni and Nd not only modulated the electronic structure of the reconstructed catalyst and the appropriate interactions for the intermediates, but also changed its potential determining step (PDS) from the O2 generation to the generation of hydroxyl oxides (i.e. O*→OOH*), which effectively reduced the energy barrier for OOH* generation, thus resulting in excellent OER performance.