Non-precious macrocycle embedded hybrid nanocomposites for efficient water oxidation

Abstract

The development of efficient electrocatalysts for OER remains a challenge owing to issues such as unfavourable mass transport, reaction thermodynamics, and kinetics. In this study, we present a novel bio-inspired polymeric cobalt(II) phthalocyanine (Poly CoTAPc) as an effective OER catalyst. Mimicking the active sites of metalloenzymes involved in biological processes, Poly CoTAPc demonstrated exceptional catalytic activity and stability. To enhance the conductivity and maximize the exposure of active sites, Poly CoTAPc was combined with Ketjen black (KB) nanoparticles. The resulting Poly CoTAPc/KB composite was subsequently coated onto a nickel foam current collector. The fabricated Poly CoTAPc/KB/Ni electrode exhibited superior electrocatalytic performance compared with that of the benchmark catalyst IrO₂ under alkaline conditions. Specifically, it achieved an overpotential of 306 mV, a low Tafel slope of 81 mV dec⁻¹, and enhanced mass activity (22.72 A g_metal⁻¹ at 1.58 V) and turnover frequency (TOF) (0.0122 s⁻¹) for the OER. Additionally, the electrode demonstrated exceptional stability and maintained performance for over 30 hours. The Poly CoTAPc/KB electrocatalyst exhibited better electron transfer capacity and good stability. Moreover, its cost-effectiveness, use of very low amount of non-precious Co metal, and eco-friendliness make this catalyst highly efficient and promising compared with traditional metal-based catalysts in advancing OER catalysts for sustainable energy applications.