Electrocatalyzed urea-assisted wastewater splitting is a promising approach for sustainable hydrogen production. However, the lack of cost-efficient electrocatalysts hinders its practical application. Herein, bimetal phosphide (NiCoP) nanowire arrays decorated with ultrathin NiFeCo metal–organic framework (NiFeCo-MOF) nanosheets on porous nickel foam (NF) were designed for urea-assisted wastewater splitting. The core–shell NiCoP@NiFeCo-MOF hybrids were prepared via successive hydrothermal, gas-phase phosphorization and hydrothermal strategies. Encouragingly, the novel NiCoP@NiFeCo-MOF/NF electrode served as an excellent bifunctional electrocatalyst for both the cathodic hydrogen evolution reaction (HER) and the anodic urea oxidation reaction (UOR) in urea-assisted water splitting, which merely required an overpotential of 44 mV to deliver a current density of 10 mA cm for HER and a voltage of 1.37 V to deliver a current density of 100 mA cm for UOR in 1.0 M KOH + 0.5 M urea. Benefiting from the highly exposed electroactive sites in exquisite three-dimensional (3D) hierarchical structure, multicomponent synergistic effect, accelerated electron transfer, easy electrolyte access and diffusion of released gas bubbles, the as-fabricated NiCoP@NiFeCo-MOF/NF exhibited outstanding electrocatalytic performance. The mechanism of water splitting was elucidated by density functional theory calculations. Interestingly, NiFeCo-MOF possessed optimized COO* adsorption ability on Ni sites that were beneficial to UOR intermediates. More significantly, this work paves the way for the design and fabrication of bifunctional electrocatalysts for urea-containing wastewater treatment and sustainable hydrogen production.

中文翻译：

---

结合金属有机骨架的双功能异质结构过渡金属磷化物尿素氧化辅助电化学水分解产氢

电催化尿素辅助废水分解是可持续制氢的一种有前途的方法。然而，缺乏具有成本效益的电催化剂阻碍了其实际应用。在此，设计了在多孔泡沫镍（NF）上装饰有超薄NiFeCo金属有机框架（NiFeCo-MOF）纳米片的双金属磷化物（NiCoP）纳米线阵列，用于尿素辅助废水分解。通过连续的水热、气相磷化和水热策略制备了核壳NiCoP@NiFeCo-MOF杂化材料。令人鼓舞的是，新型NiCoP@NiFeCo-MOF/NF电极作为一种优异的双功能电催化剂，可用于尿素辅助水分解中的阴极析氢反应（HER）和阳极尿素氧化反应（UOR），只需过电势在 1.0 M KOH + 0.5 M 尿素中，44 mV 可为 HER 提供 10 mA cm 的电流密度，1.37 V 电压可为 UOR 提供 100 mA cm 的电流密度。得益于精致的三维（3D）分级结构中高度暴露的电活性位点、多组分协同效应、加速的电子转移、易于电解质进入和释放的气泡的扩散，所制造的NiCoP@NiFeCo-MOF/NF表现出出色的电催化性能表现。通过密度泛函理论计算阐明了水分解的机理。有趣的是，NiFeCo-MOF 在 Ni 位点上具有优化的 COO* 吸附能力，这有利于 UOR 中间体。更重要的是，这项工作为用于含尿素废水处理和可持续制氢的双功能电催化剂的设计和制造铺平了道路。