Electrocatalytic Nitrate Reduction to Ammonia Over Pt-Fe3O4 Supported on Ni Foam Nanocomposite

Effective and sustainable electrocatalytic nitrate reduction is highly desirable for addressing the growing issue of global water contamination while simultaneously providing a promising pathway for the production of fossil-free ammonia under ambient conditions. In this study, a Pt-Fe₃O₄/NF nanocomposite electrocatalyst was successfully fabricated by decorating Pt and Fe₃O₄ nanoparticles onto Ni foam (NF) through a facile hydrothermal synthesis method. Comprehensive structural, morphological, and compositional characterizations confirmed the successful formation of uniformly distributed Pt-Fe₃O₄ nanostructures on the conductive NF substrate. Owing to the small particle size, high surface area, and strong synergistic interaction between Pt and Fe species, the prepared Pt-Fe₃O₄/NF nanocomposite exhibited remarkable electrocatalytic activity toward nitrate reduction. The catalyst achieved a high NH₄⁺ yield rate of 0.301 mmol h⁻¹ cm⁻² (5.418 mg h⁻¹ mg⁻¹_cat.) with an impressive Faradaic efficiency of 80.7% at −0.8 V versus RHE. The enhanced catalytic performance is attributed to the unique metallic properties, rapid charge transfer, and abundant active surface sites that facilitate both electrochemical nitrate conversion and subsequent hydrogenation processes. Furthermore, the Pt-Fe₃O₄/NF nanocomposite demonstrated excellent long-term stability, durability, and consistent catalytic performance during repeated operation cycles. Isotope labeling experiments further verified that the produced ammonia exclusively originated from nitrate reduction rather than external contamination. These findings highlight the significant potential of Pt-Fe₃O₄/NF nanocomposite for efficient nitrate wastewater treatment, sustainable ammonia recovery, and future large-scale industrial electrocatalytic applications.