Efficient Urea Oxidation on MnCO3/Ni(OH)2 Nanoflower Arrays Via Interfacial Coupling.

Abstract

The electrochemical urea oxidation reaction (UOR) presents an energy-efficient alternative to the sluggish oxygen evolution reaction (OER), operating at a substantially lower thermodynamic potential and thereby reducing the energy input for hydrogen production by approximately 70%. Simultaneously, UOR facilitates wastewater remediation, offering dual environmental and energy benefits. In this work, we report a MnCO₃/Ni(OH)₂ heterostructured nanoflower array directly grown on conductive carbon cloth that exhibits outstanding UOR catalytic activity and stability. The catalyst achieves remarkably low overpotentials of 90 mV at 10 mA·cm^-2 and 167 mV at 200 mA·cm^-2, along with excellent long-term durability under continuous operation. Comprehensive characterization and mechanistic analysis reveal that the enhanced performance originates from interfacial electronic redistribution at the MnCO₃/Ni(OH)₂ junction. This electronic interaction promotes the stabilization of highly-valent Ni active species and improves electrode wettability, thereby facilitating efficient charge transfer and mass transport. This study underscores the critical role of heterointerface engineering and compositional modulation in developing robust and high-performance UOR electrocatalysts, providing valuable insights for their practical deployment in sustainable hydrogen generation and environmental remediation.