Catalytic Reinforcement in Hybrid Imidazole Functionalized Cobalt Phthalocyanine and Ketjenblack for Boosted Hydrogen Evolution.

Abstract

Hydrogen energy is widely regarded as one of the cleanest forms of green energy due to its bio-friendly nature. However, its commercialization is restricted by many issues. One of the major issues is related to high production cost, which can be overcome by designing of effective catalysts through simple, innovative and cost-effective approach for efficient green hydrogen production. In this study, we report the synthesis of an eco-friendly, affordable, and highly redox-active tetra-imidazole functionalized cobalt phthalocyanine (TImCoPc) through a straightforward method. To ensure its purity and effectiveness as an electrocatalyst for the hydrogen evolution reaction (HER) in 0.5 M H₂SO₄, various analytical techniques are employed for its thorough characterization. The electrocatalytic performance and conductivity of TImCoPc is further enhanced by forming hybrid with highly conductive Ketjenblack (KB) in various ratios. Among the different ratios, the 3.5 : 1.5 (TImCoPc/KB) composite exhibited excellent HER performance, with an onset potential closer to that of Pt/C and an overpotential (η₁₀) of -108 mV, closely approaching the η₁₀ of Pt/C (-36 mV). Additionally, the optimized hybrid showed a lower Tafel slope of 44 mV/dec, higher turnover frequency of 3.66x10^-10 mol s^-1 cm^-2 and mass activity of 4.121 A mg^-1, with an excellent catalytic stability, thereby proving to be one of the superior electrocatalysts for HER in terms of cost, methodology, activity and efficiency. The observed enhancement in HER activity of the hybrid can be accounted to the synergistic effects that reduce the metal ion's d-band center and improve π-π interactions between the hybrid components. The composite also demonstrated an increased electrochemical active surface area. This work highlights the potential of the TImCoPc/KB (3.5 : 1.5) composite as a cost-effective and efficient catalyst for sustainable hydrogen production.