Biomimetic Hydrogen-Bond Network Engineering Regulates the Catalytic Microenvironment to Enhance Urea Electrooxidation and Selective N2 Generation

Abstract

As a crucial anodic pathway, the urea oxidation reaction (UOR) holds immense potential for the purification of nitrogenous sewage as well as the energy-saving generation of hydrogen power. However, conventional nickel-based catalysts often trigger detrimental C–N bond cleavage of urea, yielding deleterious by-products such as nitrite (NO2–) and nitrate (NO3–), which severely constrains their practical viability. Inspired by bioenzymes that regulate substrate pathways via intricate hydrogen-bonding networks, this study employed Ni(OH)2 as a scaffold to engineer an enzyme-mimetic dynamic hydrogen-bonding microenvironment through the coordination of terephthalic acid (TPA) with Ni sites. This strategy enables the precise modulation of the UOR pathway. Driven by a minimal potential of just 1.41 V vs. the reversible hydrogen electrode (RHE), the synthesized Ni(OH)2-TPA/NF electrode demonstrated exceptional UOR catalysis, achieving a response current density of 100 mA cm–2. Furthermore, it demonstrated exceptional N2 selectivity and Faradaic efficiency while maintaining robust structural and electrochemical stability over a 48 h chronoamperometric test. Mechanistic insights from density functional theory (DFT) simulations combined with in situ Fourier transform infrared (FTIR) analysis confirmed that the configuration of urea molecules was accurately constrained by the TPA-mediated hydrogen-bonded matrix. This spatial confinement optimized the N–N coupling process while successfully suppressed the rupture of C–N linkages. This work overcomes the critical bottleneck of suboptimal UOR selectivity in traditional nickel-based systems, offering a new paradigm for the development of high-efficiency, sustainable catalysts and providing a theoretical foundation for the industrialization of urea electrolysis in environmental and energy applications.