fig2

From: Multi-functional engineering of rare earth-based catalysts for high-efficiency water splitting

Figure 2. (A) Schematic model of epitaxial growth of Sr and Fe-doped LaNiO₃ perovskite thin films on STO (001) substrate; (B) Schematic representation of the electronic coupling between Ni³⁺ and Fe⁴⁺ in SrLNFO-0.2. This figure is quoted with permission from Fu et al.^[50]; (C) HAADF-STEM image and elemental mappings of La-RuO₂. This figure is quoted with permission from Zhu et al.^[54]; (D) HER polarization curves of CeNiFe-MOF‖CeNiFe-MOF and Pt/C‖IrO₂ for water electrolysis; (E) OER polarization curves; (F) The free energy diagram for the HER process. This figure is quoted with permission from Yang et al.^[55]. STO: SrTiO₃; HAADF-STEM: high-angle annular dark-field scanning transmission electron microscopy; MOF: metal-organic framework; OER: oxygen evolution reaction; HER: hydrogen evolution reaction.