“…Heretofore, IrO 2 and RuO 2 , and other precious metal-based electrocatalysts, are known as pioneering OER catalysts. However, their rarity and high cost preclude them from being employed in large-scale adoption. − As a result, developing low-cost, earth-abundant, and highly stable electrocatalysts is of utmost priority. ,− Significant endeavors have been sanctified to design and produce transition metal-based materials, such as metal oxides, metal hydroxides, metal sulfides, metal phosphides, and metal-embedded mesoporous carbon (metal/MC) materials. ,, Among them, metal/MC materials received considerable attention. This is attributed to the presence of defects and nitrogen doping to promote the electrical conductivity, lower the overpotential, enhance the electrochemical stability, and promote the electro-transfer process at the electrode/electrolyte interface. ,, …”