Authors: Sumana Podder, Ragunath Madhu, Subrata Kundu, Joyee Mitra
Published: 2025-03-17
Source: Full article
AbstractThe potential of cobalt catalysts for sustainable, carbon‐neutral hydrogen production through water splitting can be fully achieved by fundamental understanding‐driven strategic tuning of metal oxidation states on a uniform scaffold. In pursuit of a stable scaffold that can enhance electrocatalytic activity through metal‐N synergism and envisaging that g‐C3N4 has inherited its properties from its structurally distinct predecessor, Melem; a comprehensive exploration of s‐heptazine (Melem, M) is furnished as host for strategic tuning of cobalt electrocatalysts having variable oxidation states. Co(II)‐doped heptazine (CoII@M) catalyzed oxygen evolution reaction (OER) with an overpotential of 302 mV achieving 50 mA cm−2 current density, with minimal charge‐transfer resistance (0.41 Ω). Co(0)‐doped heptazine nanotube (Co0@M) facilitated the arduous H‐O‐H bond cleavage for alkaline hydrogen evolution reaction (HER), achieving 50 mA cm−2 current density at 206 mV overpotential, with low charge‐transfer resistance of 0.66 Ω, attesting to the scaffold's assistance to electron transfer. The CoII@M||Co0@M assembly shows low cell voltage (1.637 V @ 10 mA cm−2) and promising stability (114 h) for total water splitting. s‐heptazine scaffold ensured finer dispersion and stabilization of cobalt active sites in a corrosive environment. The scaffold's substantial stability, attributes to its nitrogen‐rich core and extensive H‐bonding, unlocks the potential of under‐explored melem‐based systems for electrocatalytic applications.