text: Catalysts based on synthetic metalloporphyrins have been extensively investigated, although few or no applications exist. Due to their distinctive redox properties, Co(II)–porphyrin-based systems are radical initiators. Some complexes emulate the action of various heme enzymes such as cytochrome P450, lignin peroxidase. Metalloporphyrins are also studied as catalysts for water splitting, with the purpose of generating molecular hydrogen and oxygen for fuel cells.
  In addition, porous organic polymers based on porphyrins, along with metal oxide nanoparticles,