Low‐Voltage Hydrogen Production via Hydrogen Peroxide Oxidation Facilitated by Oxo Ligand Axially Coordinated to Cobalt in Phthalocyanine Moiety

Abstract

AbstractA cobalt phthalocyanine having an electron‐poor CoN4 (+δ) in its phthalocyanine moiety was presented as an electrocatalyst for hydrogen peroxide oxidation reaction (HPOR). We suggested that hydrogen peroxide as an electrolysis medium for hydrogen production and therefore as a hydrogen carrier, demonstrating that the electrocatalyst guaranteed high hydrogen production rate by hydrogen peroxide splitting. The electron deficiency of cobalt allows CoN4 to have the highly HPOR‐active monovalent oxidation state and facilitates HPOR at small overpotentials range around the onset potential. The strong interaction between the electron‐deficient cobalt and oxygen of peroxide adsorbates in Co─OOH− encourages an axially coordinated cobalt oxo complex (O═CoN4) to form, the O═CoN4 facilitating the HPOR efficiently at high overpotentials. Low‐voltage oxygen evolution reaction guaranteeing low‐voltage hydrogen production is successfully demonstrated in the presence of the metal–oxo complex having electron‐deficient CoN4. Hydrogen production by 391 mA cm−2 at 1 V and 870 mA cm−2 at 1.5 V is obtained. Also, the techno‐economic benefit of hydrogen peroxide as a hydrogen carrier is evaluated by comparing hydrogen peroxide with other hydrogen carriers such as ammonia and liquid organic hydrogen carriers.