Efficient Oxygen Evolution Using Conductive Nitrogen-rich Ferrocene-based Porous Organic Polymers Electrocatalysts

The development of stable, efficient, and cost-effective electrocatalysts for the oxygen evolution reaction (OER) is critically important due to the intrinsically sluggish kinetics of this process, which significantly limit the efficiency of water splitting and related electrochemical energy systems. Porous organic polymers (POPs) have recently emerged as a versatile platform for the design of heterogeneous catalysts; however, their application in water-splitting electrocatalysis, particularly for the OER, remains largely unexplored. In this work, two novel ferrocene-based porous POP electrodes were designed, synthesized, and subsequently supported on nickel foam (NF) for evaluation as OER electrocatalysts. The resulting electrodes exhibit remarkable electrocatalytic activity and excellent operational stability under alkaline OER conditions. Notably, in 1.0 M KOH, the most active catalyst, Fc-PBTD POP, achieves a low overpotential of approximately 291 mV at a current density of 10 mA cm⁻², along with a small Tafel slope of 86 mV dec^-1. Furthermore, the catalyst demonstrates outstanding durability, retaining its activity with negligible performance degradation over 15 h of continuous chronoamperometric operation. Electrochemical analyses reveal that the superior OER performance originates from the incorporation of ferrocene units, which act as efficient electron-transfer mediators, facilitating rapid charge transport and enhancing overall catalytic activity. This study represents a significant advancement in the design of ferrocene-functionalized porous POP electrocatalysts and contributes new insights into their potential for energy-related electrocatalytic applications.