FeNi3 nanoparticles for electrocatalytic synthesis of urea from carbon dioxide and nitrate†

Abstract

Due to the environmental pollution and high energy consumption associated with the conventional industrial Bosch–Meiser method, electrocatalytic urea synthesis emerges as a promising and sustainable alternative route. In this work, we constructed and utilized nitrogen-doped porous carbon loaded with bimetallic FeNi₃ alloy nanoparticles as an efficient electrocatalyst for synthesizing urea from carbon dioxide (CO₂) and nitrate (NO₃⁻). The created FeNi₃ alloy within FeNi/NC served as the active site for the C–N coupling reaction, generating a higher urea yield of 496.5 μg h⁻¹ mg_cat.⁻¹ with a correlating faradaic efficiency (FE) of 16.58% at −0.9 V versus the reversible hydrogen electrode (vs. RHE), when in comparison to monometallic Fe/NC and Ni/NC catalysts. Moreover, we also monitored the urea generation process via in situ Raman spectroscopy technology, which enabled the identification of two critical reaction species, namely O–C–O and N–C–N, inferring that C–N coupling acted as the key reaction step.