Synergistic Effects of Fe2O3 Clusters and Iron Phthalocyanine on Carbon Nanotubes for Enhanced Electrochemical Nitrate Reduction.

The electrochemical nitrate reduction reaction (NO3RR) has attracted considerable attention for the sustainable production of NH3, urea, amino acids, and other value-added chemicals. Among these, NH3 is particularly significant due to its large-scale industrial synthesis via the Haber-Bosch process. Herein, we report the design of an efficient NO3RR catalyst prepared through a simple synthesis route. Fe2O3 clusters (2-5 nm) were uniformly deposited on iron phthalocyanine (FePc)-modified N-doped carbon nanotubes (Fe2O3/FePc/CNT), yielding a high NH3 production rate of 58.67 mg h-1 cm-2 with a Faradaic efficiency (FE) of 81.89% at -1.0 V versus RHE. Comparative studies with FePc/CNT, Pc/CNT, and Fe2O3/CNT confirmed the synergistic effect between Fe2O3 clusters and FePc, with the optimized Fe2O3/FePc/CNT catalyst showing superior activity and selectivity. Furthermore, the optimized catalyst exhibited excellent stability for 24 h. A possible mechanism for NH3 formation is proposed on the basis of the reaction intermediates identified by ex situ FTIR and x-ray photoelectron spectroscopy (XPS) analyses.