Sonochemical‐Assisted Synthesis of Ultrathin NiCu layered Double Hydroxide for Enhanced CN Coupling toward Electrocatalytic Urea Synthesis

Abstract

The electrocatalytic carbon–nitrogen (CN) coupling, facilitating one‐step urea synthesis under ambient conditions, holds great promise as a viable alternative to conventional protocols. However, developing efficient and low‐cost electrocatalysts for CN coupling remains a great challenge. Herein, a “bottom‐up” strategy is proposed to synthesize multidimensional hybrid materials of ultrathin NiCu layered double hydroxide (LDH) nanosheets on carbon nanofiber (u‐NiCu‐LDH/CNF) through an ultrasonic‐assisted solvothermal method. The NiCu‐LDH nanosheets in the u‐NiCu‐LDH/CNF composite exhibit a significantly thinner morphology compared to NiCu‐LDH/CNF prepared by conventional solvothermal without ultrasonic assistance. Leveraging its large specific surface area and well‐exposed active sites, the u‐NiCu‐LDH/CNF demonstrates dramatically improved electrocatalytic activity in CN coupling for urea production, leading to a satisfactory urea yield rate (19.43 mmol g−1 h−1) and a high Faradaic efficiency (13.95%). Density functional theory calculations reveal that the CN coupling step on the NiCu‐LDH model starts through the reaction between *NO2 and *CO2 intermediates. This spontaneous CN coupling process is beneficial in promoting high levels of urea yield. This work presents a facile approach for preparing 2D ultrathin LDH, showcasing tremendous prospects in electrocatalytic urea synthesis.