Synergistic multiphase lattice strains and built-in electric field in lignin-derived carbon coupled with Mo-Cu-Ni multimetallic for enhanced urea-assisted water electrolysis

Abstract

Nickel-based catalysts play a crucial role in urea-assisted water electrolysis but are hampered by uneven adsorption-desorption processes and slow kinetics in the urea oxidation reaction (UOR) and hydrogen evolution reaction (HER). In this study, we present a self-supported catalyst named MoO₂/Cu/Ni@LC, which combines lignin-derived carbon with MoO₂/Cu/Ni and grows on nickel foam. MoO₂/Cu/Ni@LC features multiphase heterogeneous interfaces that induce interfacial lattice strains and built-in electric fields. These characteristics increase lattice distortions and optimize the electronic structure, thereby enhancing the intrinsic activity of UOR/HER. As a result, MoO₂/Cu/Ni@LC achieves small/large current densities of ±10/±1500 mA cm⁻² at 1.26/1.42 V (UOR) and − 65.55/−379.07 mV (HER). Moreover, MoO₂/Cu/Ni@LC demonstrates remarkable stability by enduring 140 h of testing at ±500 mA cm⁻² for both UOR and HER. This stability is attributed to the corrosion resistance of lignin-derived carbon, efficient electron transfer facilitated by multiphase heterogeneous interfaces, and a self-supported structure that enhances gas-liquid transport. Notably, when employed in a membrane electrode assembly, MoO₂/Cu/Ni@LC exhibits an impressive low potential of 1.71 V at 500 mA cm⁻² and maintains stable operation for 120 h. This work not only highlights a promising strategy for advancing nickel-based catalysts in practical urea-assisted water electrolysis applications but also offers valuable insights into designing catalysts for organic molecular oxidation reactions, such as those involving 5-hydroxymethylfurfural, methanol, etc.