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

Abstract

Effective and sustainable electrocatalytic reduction of nitrate is greatly desired to solve the problem of global water contamination and provide a promising way to generate fossil-free ammonia. In this regard, Pt-Fe₃O₄ nanoparticles are decorated on Ni foam (NF) using the hydrothermal method to achieve Pt-Fe₃O₄/NF nanocomposite electrocatalyst. Various characterization techniques investigate the structural and morphological properties of Pt-Fe₃O₄/NF nanocomposite. Benefiting from the small size of Pt and Fe nanoparticles, the Pt-Fe₃O₄/NF nanocomposite reveals excellent performance for electrocatalytic nitrate reduction with an NH₄⁺ yield rate of 0.301 mmol h⁻¹ cm⁻² (5.418 mg h⁻¹ mg⁻¹_cat.) and Faradaic efficiency of 80.7% at − 0.8 V vs. RHE. Pt-Fe₃O₄/NF nanocomposite exhibits unique metallic properties and abundant surface sites due to a synergistic effect of Pt-Fe nanostructure favorable for the electrochemical and hydrogenation reduction processes. Moreover, Pt-Fe₃O₄/NF nanocomposite reveals outstanding long-term stability and durability. Isotope labeling experiments are performed, and results demonstrate that ammonia originates from nitrate reduction. These favorable outcomes of Pt-Fe₃O₄/NF nanocomposite emphasize its potential for treating nitrate wastewater for ammonia recovery and prospects for its industrial applications.

Graphical Abstract

An efficient electrocatalyst was prepared by fabricating Pt-Fe₃O₄ on NF using hydrothermal method for electrochemical nitrate reduction to ammonia. Pt-Fe₃O₄/NF showed a remarkable NH₄⁺ yield rate with high Faradaic efficiency at − 0.8 V vs. RHE. Also, the Pt-Fe₃O₄/NF nanocomposite exhibited outstanding stability and durability.