Figure 2. (A and B) TEM images of RuO2/NiFe(OH)x; (C) High-resolution TEM image of RuO2/NiFe(OH)x; (D-G) Elemental mapping images of RuO2/NiFe(OH)x; (H-J) XPS spectra for Ni 2p regions, Fe 2p regions and Ru 3p regions. TEM: Transmission electron microscopy; XPS: X-ray photoelectron spectroscopy.