3D Hierarchical NiCo Layered Double Hydroxide Nanosheet Arrays Decorated with Noble Metal Nanoparticles for Enhanced Urea Electrocatalysis

The electrocatalysis of urea represents an important potential as an efficient technology for sustainable energy development. This anodic reaction generates hydrogen or electrical power through direct electrooxidation of urea molecules, but is greatly inhibited by its slow kinetics. Therefore, tailoring highly efficient, earth-abundant, and durable electrocatalysts for urea oxidation reaction (UOR) is a fundamental for the enhancement of green energy conversion technologies. Herein, we report a scalable synthetic strategy to construct three-dimensional (3D) nickel-cobalt layered double hydroxide nanosheet arrays (NiCo-LDH NSAs) with silver (Ag-0) or gold (Au-0) and palladium (Pd-0) intercalants as high performance catalysts for UOR. Experimental results suggest that the interlayer spacing of multi-anions LDH NSAs can effectively afford synergetic effects of increased electrochemical surface area, better exposure of catalytically active sites, and favorable adsorption energy of urea molecules. As expected, the deposition of noble metal nanoparticles (NPs) could successfully modulate the electronic structure, delivering a rise to significantly improved UOR activity. Specifically, the Au/NiCo-LDH hybrid exhibits a superior electro-catalytic performance toward urea electrooxidation with a highest current. These findings offer an effective pathway to prepare potential earth-abundant electrocatalysts for direct urea fuel cells (DUFCs).