Fig. 6. (a) PDOS of Rh-Co₃O₄ (100); (b) charge density difference of Rh-Co₃O₄ (100) upon the combination of two counterparts (yellow color represents charge accumulation, and blue color represents charge depletion in the space); (c) surface Pourbaix diagram at 25 °C; (d) Gibbs free energy diagrams of Co₃O₄ and Rh-Co₃O₄ (100) for the HER; (e) Gibbs free energy diagrams of Co₃O₄ and Rh-Co₃O₄ (100) for the HzOR; in situ Raman spectrum of (f) Co₃O₄ BNSs and (g) Rh-Co₃O₄ BNSs.