Transition metal–phenanthroline intercalated montmorillonite as efficient electrocatalysts for the oxygen evolution reaction

Abstract

With the escalating climate crisis, the development of efficient, low-cost energy sources with minimal carbon footprints is more critical than ever. Among various green energy solutions, hydrogen production via water electrolysis has garnered significant attention due to the abundance of water and the cleanliness of hydrogen as a product. However, the widespread adoption of this technology is hindered by the sluggish kinetics of the oxygen evolution reaction (OER) at the anode, which compromises its economic viability compared to conventional hydrogen production methods. Addressing this challenge requires the development of highly efficient OER electrocatalysts to reduce overpotential and improve reaction kinetics. In this study, we present a novel strategy for synthesizing OER electrocatalysts by intercalating organo-metallic complexes of 1,10-phenanthroline (Phen) coordinated with Ni, Co, and Fe into the interlayers of montmorillonite (MMT) clay. Structural analyses using X-ray diffraction (XRD), small-angle X-ray scattering (SAXS), and transmission electron microscopy (TEM) confirmed the successful insertion of the complexes, evidenced by an increase in the interlayer spacing of the MMT. Electrochemical performance evaluations revealed that MMT:Co(Phen)₂ exhibited the best OER activity, achieving an overpotential of 313 mV at a current density of 10 mA cm⁻², along with excellent stability over 50 hours of operation.