Iron-Coordinated Thiourea Formaldehyde Metal-Organic Framework for Efficient Water Splitting

A key challenge in the oxygen evolution reaction (OER) is the development of efficient and durable catalysts for applications such as water electrolyzers and metal-air batteries. Due to sluggish reaction kinetics, the OER typically requires an overpotential significantly higher than the thermodynamic potential of 1.23 V vs RHE, which limits the overall efficiency of electrochemical energy systems. In this work, we report the design and synthesis of an iron-coordinated thiourea-formaldehyde framework, denoted as (Fe-TF) _n , as a nonprecious metal-based electrocatalyst for the OER. Its significance lies in the integrated coordination of iron with sulfur and nitrogen atoms within the thiourea-formaldehyde framework. This coordination enables strong dπ-pπ interactions, which enhance electron delocalization and improve electronic conductivity, thereby boosting the catalytic activity of the material. When supported on Ketjen Black, (Fe-TF) _n exhibited an OER potential (E _j10) of 1.53 V vs RHE at a current density of 10 mA/cm² and demonstrated stability over 300 h of continuous operation. Furthermore, to evaluate its practical viability, the catalyst was incorporated into a membrane electrode assembly (MEA), and achieved a current density of 70 mA/cm² at 2.1 V in a water electrolyzer.