Decorating a highly conjugated and electron-rich Co-MOF with Ni3S2 for improved oxygen evolution and urea oxidation reactions

Abstract

The development of high-performance non-noble metal electrocatalysts for water splitting is critical for sustainable hydrogen production but remains challenging due to the moderate activity, sluggish kinetics, and unsatisfactory durability of oxygen evolution reaction (OER) catalysts. To overcome these limitations, this work integrates rigid conjugated metal–organic frameworks (MOFs) with heterointerface engineering to boost electrocatalytic performance. Furthermore, substituting the energy-intensive OER with the urea oxidation reaction (UOR) presents a promising approach to lower energy consumption. Herein, we design and synthesize a composite catalyst, Ni₃S₂-CoFcDCA/NF, comprising Ni₃S₂ and a cobalt ferrocenedicarboxylate MOF. The synergistic interaction between Ni₃S₂ and CoFcDCA not only enhances electron transfer but also exposes abundant active sites, resulting in exceptional OER and UOR performance. The catalyst achieves a current density of 50 mA cm⁻² at a remarkably low overpotential of 202 mV for the OER and a 1.39 V cell voltage for the UOR in alkaline media. Density functional theory calculations reveal that the optimized d-band center position in NiOOH/CoFcDCA regulates the adsorption energetics of oxygen intermediates, particularly lowering the activation barrier for the OH* → O* transition, thereby accelerating the OER kinetics. This study highlights the potential of heterostructured MOF-based catalysts for efficient water splitting and offers valuable guidance for designing cost-effective non-noble-metal electrocatalysts.