Cu loading modulated NiFe based composit

Electrocatalytic nitrate reduction reaction (NO3RR) offers a sustainable approach for ammonia synthesis, yet it faces challenges such as sluggish kinetics and low selectivity due to the eight-electron transfer process. This study aims to construct an efficient multimetallic tandem catalyst by synthesizing a series of spherical Cu2O/NiFeCu(OH)x composites using a one-pot hydrothermal method, varying the Cu(NO3)2 loading to optimize performance. The catalysts were characterized through various techniques, including X-ray diffraction and electron microscopy. The evaluation of electrochemical performance was conducted in a specific electrolyte, employing methods like cyclic voltammetry and chronoamperometry, with ammonia quantification achieved via the indophenol blue method and NMR analysis. The findings revealed that the optimized Cu2O/NiFeCu(OH)x, with 1× Cu loading, produced an ammonia yield of 8.86 mg h−1 mgcat−1 and a Faradaic efficiency of 94% at -0.6 V vs. RHE, significantly outperforming control samples. Furthermore, the catalyst maintained stable activity over 12 hours at -0.4 V vs. RHE, showcasing robust performance over multiple cycles. This research highlights the effectiveness of excess Cu loading in enhancing the tandem behavior of iron-group/copper catalysts in nitrate electroreduction to ammonia.