Construction of hierarchical nanostructures and NiO nanosheets@nanorods for efficient urea electrooxidation

Hierarchical NiO nanosheets@nanorods have been rationally designed and constructed for efficient urea electrooxidation in an alkaline solution. The critical synthetic strategy, engaging the one-step anion -competitive reaction, precisely integrates two nickel-based materials into a heterostructure with Ni(OH)2 nanosheets and NiC2O4 nanorods. Benefiting from the hierarchically porous structure and high specific surface area, the NiO NNs can improve the escape efficiency of gas in electrochemical reactions and main-tain sustainability. Furthermore, this distinctive structure can expose highly dispersed active sites for en-hancing urea molecules' adsorption, surface-dependent redox reactions, and electrical conductivities. As a result, these hierarchical NiO nanosheets@nanorods exhibit superior activity with a low overpotential of 156 mV at 10 mA/cm2, and a slight Tafel slope of 40.7 mV/dec, and high stability with almost no decay of 12,0 0 0 s for urea electrooxidation. This work promotes the application of well-designed hierarchical structure in electrooxidizing urea and provides a possibility for highly efficient electrolysis of alkaline urea wastewater.(c) 2023 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.

Automated summary

Hierarchical NiO nanosheets@nanorods have been designed and constructed for efficient urea electrooxidation in alkaline solution. The integration of Ni(OH)2 nanosheets and NiC2O4 nanorods in a heterostructure through one-step anion-competitive reaction strategy results in the hierarchically porous structure and high specific surface area. These NiO nanosheets@nanorods exhibit superior activity with a low overpotential, slight Tafel slope, and high stability in urea electrooxidation. This work promotes the application of well-designed hierarchical structure in electrooxidizing urea.