Cobalt–benzimidazole swapped metal–organic macrocycle with reduced graphene oxide as a hybrid electrocatalyst for highly efficient oxygen evolution reaction

Abstract

The increasing global demand for sustainable and efficient energy-conversion technologies necessitates the development of high-performance electrocatalysts for the oxygen evolution reaction (OER). Herein, we present a novel electrocatalyst, namely a cobalt-benzimidazole substituted metal–organic phthalocyanine with reduced graphene oxide (CoBImPc/rGO) hybrid, for boosting the catalytic activity and stability for the OER, with potential applications in water splitting and energy-storage systems. The synthesis of CoBImPc/rGO involved integrating cobalt–benzimidazole substituted metal–organic phthalocyanine onto reduced graphene oxide, resulting in a well-defined hybrid structure. Based on comprehensive characterization, including scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) spectroscopy, we confirmed the homogeneous distribution of CoBImPc particles on the rGO sheets and the successful incorporation of the elements cobalt, carbon, nitrogen, bromine, and oxygen in the final hybrid material. Electrochemical evaluations based on cyclic voltammetry demonstrated that the CoTBImPc/rGO hybrid manifested a significantly improved current density and lower overpotential than pure CoTBImPc and rGO, indicating its enhanced electrocatalytic activity. Furthermore, the Tafel slope obtained from the Tafel plot was substantially reduced, suggesting a faster kinetics for the OER on the hybrid electrocatalyst. Notably, the CoTBImPc/rGO hybrid electrocatalyst revealed excellent stability and durability during long-term electrolysis tests, maintaining its catalytic activity even after prolonged operation. When CoTBImPc/rGO was coated with Ni foam and used as an OER catalyst, it showed a lower overpotential of 350 mV at a current density of 10 mA cm⁻². This impressive electrocatalytic performance and stability of the CoTBImPc/rGO hybrid make it a promising candidate for clean energy applications, with the potential to contribute to sustainable energy-conversion technologies and a greener future.