The OER performance of LNO, LNO-Vo and LNO-Vo' was evaluated in 1 M KOH by cyclic voltammetry with a scan rate of 10 mV/s. In order to eliminate the influence of Fe impurities in KOH electrolyte on the performance of OER, the KOH electrolyte that we used has been purified. Figure shows the CV plot of LNO, LNO-Vo and LNO-Vo' after 10 CV cycles of the activation process with the potential ranging from +1.0 to +1.5 V vs RHE. The potential is iR compensated by solution resistance. It shows that introducing of oxygen vacancies in the LNO can enhance the OER performance, which is consistent with previous studies. In addition, we note that the OER performance of LNO-Vo' is much higher than that of LNO-Vo, which is attributed to the higher concentration of oxygen defects in LNO-Vo' as shown in the above XPS results.