Unleashing the Bifunctional Activity of Iron Phthalocyanine–Reduced Graphene Oxide Hybrid for Water Electrolysis
Shantharaja Daniel, Gouthami Patil, Srinivasa Budagumpi, Bhaskar Besagarahally Laxmaiah, Lokesh Koodlur Sannegowda
Abstract
The development of an efficient and highly durable bifunctional electrocatalyst for the water-splitting reaction is crucial for practical applications to meet energy requirements. Herein, 4-amino-3-naphthalene-2-sulfonic acid trifunctional monomer is infused to iron phthalocyanine (FeSPc) to tune the properties and evaluated as a bifunctional catalyst for water electrolysis, i.e., the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The designed catalyst is characterized by using various spectroscopic and analytical techniques. The synthesized supramolecule is treated with reduced graphene oxide (rGO), and the resulting hybrid is coated on a glassy carbon electrode (GCE) and evaluated for HER and OER bifunctional activity for water electrolysis. The rGO:FeSPc/GCE electrode exhibited a lower overpotential of 93 and 350 mV at 10 mA cm –2 for HER and OER in 0.5 M H 2 SO 4 and 1.0 M KOH electrolyte, respectively. Furthermore, the fabricated rGO:FeSPc/Ni-foam electrode manifested a lower overpotential of 330 mV for the OER at a current density of 10 mA cm –2 in 1.0 M KOH electrolyte at a scan rate of 5 mV s –1 . The Tafel slope value for the designed electrode is 39 mV dec –1 for both the HER and the OER, indicating facile reaction kinetics and efficient hydrogen and oxygen evolution. Additionally, the electrocatalyst showed greater stability and durability for long-period performance by retaining its catalytic activity without any significant degradation of the structure. The fabricated bifunctional catalyst has the ability to replace precious monofunctional benchmark catalysts like Pt/C and IrO 2 and can overcome the associated complexity in water electrolysis.