Interfacial engineering of the hetero-coordinated Ru–O-M clusters in MOF/LDH structures for boosting urea-assisted water splitting

Abstract

Urea oxidation reaction (UOR) assisted water splitting has attracted tremendous interests for efficient hydrogen production, but the sluggish reaction kinetics still hinders its extensive application. Herein, the well-defined Ru clusters anchored on metal-organic framework (MOF)/layered double hydroxide (LDH) heterointerface (Ru@MOF/LDH) was prepared via an interface-induced strategy. By hydrolyzing the MOF precursor, confined sites-rich intermediate MOF/LDH heterostructure formed, providing numerous anchor sites to confine Ru. Inspiringly, monodispersed Ru clusters and hetero-coordinated Ru–O-M bonds successfully fabricated on the heterointerface between MOF and LDH. Benefiting from the well-designed Ru clusters, Ru–O-M bonds and multicomponent synergistic effect, the blossom-like Ru@MOF/LDH exhibited outstanding activities for hydrogen evolution reaction (HER) and UOR bifunctionality in alkaline electrolyte. Optimized Ru@MOF/LDH displayed an ultra-low overpotential of 84.7 mV for HER to reach 10 mA cm⁻² and only with the potential of 1.44 V to achieve a current density of 100 mA cm⁻² for UOR. For a two-electrode electrolyser, Ru@MOF/LDH drove a urea-assisted water splitting to reach 10 mA cm⁻² at a low cell voltage of 1.4 V, which was superior to most of the reported LDH-based catalysts. This work provides profound insights for designing the MOF-based heterostructure electrocatalysts, further improving catalytic performance.