Sonochemical-Assisted Synthesis of Ultrathin NiCu layered Double Hydroxide for Enhanced C-N Coupling toward...

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.