MOF-Driven Direct Oxidative Electrocatalysis of Urea

Abstract

Achieving high efficiency, stability, and mechanistic clarity in urea electro-oxidation is vital for advancing sustainable energy and environmental remediation. Here, we present a rationally engineered class of TiO2-supported Ni–Cu bimetallic metal–organic frameworks (MOFs) exhibiting catalytic activity with reaction dynamics conventionally not observed before. The Ni0.5Cu0.5@TiO2 platform demonstrates a record-high enhancement factor (∼8470), an ultralow charge transfer resistance (∼3 Ω), and an extraordinary Tafel slope of 9 mV dec–1, surpassing all current Ni-based and noble-metal catalysts. Extensive spectroscopic, electrochemical, and surface interrogation scanning electrochemical microscopy (SI-SECM) studies reveal that these heterostructures promote a direct urea oxidation pathway stabilized by oxygen vacancies, electronic synergism, and optimized metal oxidation states, notably facilitating Ni3+ active sites. The electrocatalytic system exhibits a TOF of 8.58 × 103 s–1, outstanding stability over 72 h, and tunable surface chemistry that accelerates charge transfer and stabilizes catalytically active phases. This mechanistic dissection underlines the importance of defect engineering, electronic modulation, and heterostructure architecture in unlocking the full potential of MOF-based catalysts, thereby contributing to the design of next-generation catalysts that transcend current limits.