To investigate the effect of electrochemical treatments on the surface morphology of the different thin films, we carried out AFM measurements for LNO, LNO-Vo and LNO-Vo' after 1000 CV cycles, the results are shown in Figure . After 1000 CV, the RSM of LNO decreased from 3.75 nm (Fig. ) to 1.97 nm (Figure ), the RSM of LNO-Vo decreased from 4.14 nm to 1.98 nm, while the RSM of LNO-Vo' increased from 0.85 nm to 2.65 nm. The change in RMS of LNO, LNO-Vo and LNO-Vo' after 1000 CV cycles can be most likely ascribed to surface reconstruction of those thin film with OER cycling and is in good accordance with the XRD results (Figure ). The influence of OER treatment on the surface properties of LNO, LNO-Vo and LNO-Vo' films can be further observed in the corresponding AFM 3D images in Figure . Among them, the changes in the LNO-Vo' film due to OER treatment were most pronounced.