Cascade Design and Facile Fabrication of Cu/Cu2O/CuAl‐Layered Double Hydroxides as Efficient Nitrate Reduction Electrocatalysts

Abstract

Nitrate (NO3¯) reduction reaction (NITRR) presents a promising pathway for the production of renewable NH3 while concurrently decontaminating NO3¯ wastewater. However, the multi‐electron transfer sequence and complex reaction network involved in NO3¯ conversion pose significant challenges to achieving high Faradaic efficiency (FE). Herein, this work presents ternary Cu/Cu2O/CuAl‐layered double hydroxides (LDHs) catalysts designed through a cascade approach and synthesized via a straightforward one‐step electrodeposition method. The resulting catalysts demonstrate peak activity at −0.4 V versus RHE, achieving an impressive of 92.0%, which significantly surpasses most reported binary and ternary catalysts. Density functional theory calculations and atomic force microscopy reveal that the Cu/Cu2O/CuAl‐LDHs exploit cascade design by integrating three distinct functions essential for efficient NO3¯ reduction: CuAl‐LDH initiates NO3¯ adsorption, Cu(111) and Cu₂O(111) cooperatively facilitate NO3¯ activation, and Cu(111) promotes NH3 desorption. Durability tests further confirm that both NH3 yield and remain stable after 10 cycles, indicating the excellent stability of the Cu/Cu2O/CuAl‐LDHs catalysts. These findings underscore the critical role of cascade design strategies in enhancing the performance of electrocatalysts for NO3¯ reduction to NH3, providing a transformative approach for sustainable ammonia synthesis.