Engineering Cu, Mn, and Co-Modified Graphene/Ferrites on Gas Diffusion Layers Electrodes for Efficient Electrocatalytic Nitrogen Reduction to Ammonia

Abstract

Graphene with spinel ferrites (MFe₂O₄, M: Mn, Co, and Cu) is excellent low-cost material as electrocatalysts for ammonia synthesis. This study investigated the enhanced electrocatalytic efficiency of GDL/graphene-MnFe₂O₄, GDL/graphene-CoFe₂O₄, and GDL/graphene-CuFe₂O₄ for the reduction of nitrogen (N₂) and addressed gaps in ammonia (NH₃) synthesis via electrocatalytic N₂ reduction, seeking decentralized, low-carbon alternatives to the Haber–Bosch process. The materials were synthesized using water rich in natural organic matter as a solvent and were deposited onto a gas diffusion layer (GDL) electrode using the drop-coating method. The main results highlighted the efficiency of all electrodes, but a higher yield was obtained for GDL/graphene-MnFe₂O₄, which reached 48 µg h⁻¹ cm⁻² and a faradaic efficiency of 56%. These findings highlight the influence of transition-metal substitution on the stability of ferrite compounds and illustrate a simple and cost-effective method for obtaining an efficient alternative for NH₃ synthesis using electrocatalysts prepared from economic precursors.