The crystal structure of the pure NixCo3-xO4 (x = 0, 0.3, 1.0) targets was analyzed by Xray diffraction (XRD) using Cu Kα radiation generated at 40 kV and 44 mA. Thin film growth was examined by high-resolution X-ray diffraction using a rotating Cu anode (45 kV, 190 mA) Rigaku SmartLab diffractometer in θ-2θ geometry, equipped with a Ge (220) double bounce monochromator (selecting the Cu Kα1 wavelength) in parallel beam mode, while the thickness of the films was determined by X-ray reflectivity (XRR) scans on the SmartLab diffractometer. The surface morphologies of the LaNiO3 sample before and after OER treatments were determined by atomic force microscopy (AFM) with Bruker Icon Dimension AFM in amplitude modulation mode using PPP-Zeihr cantilevers (NanoAndMore GmbH, Wetzlar, Germany). This type of cantilever has a nominal spring constant of 27 N/m, a nominal resonance frequency of 130 kHz, and a typical tip radius of <7 nm. The free oscillation amplitude of the cantilever tip was adjusted to A0 ≈ 120 nm, and a setpoint ratio of Asp/A0 ≈ 0.7 was set to ensure operation in the repulsive tip-sample interaction regime. We scanned the surface with a tip velocity of 2 μm/s. The X-ray photoelectron spectroscopy (XPS) was performed with a hemispherical energy analyzer (PHOIBOS 150, Focus 500 with XR50M) at a pressure <10 -9 mbar and monochromatized Al Kα radiation (1486.74 eV) was utilized for excitation. Survey spectra were recorded with a pass energy of 20 eV and detailed spectra were recorded at 10 eV. The system was calibrated to 0.00 eV binding energy of the Fermi level by the core lines of copper, silver, and gold as well as to the emission lines of Au 4f7/2 at 83.98 eV, Ag 3d5/2 at 368.26 eV, and Cu 2p3/2 at 932.67 eV binding energy with deviations ≤0.1 eV. The data was analyzed with CasaXPS, version 2.3.24. The spectra were fitted with Shirley background and peaks are fitted with GL (30) lineshapes.