Ferrocene-Engineered Bimetallic MOF Nanoflowers Boost Selective CO₂-to-CH₄ Electrocatalysis via Dual-Metal Synergy...

Electrocatalytic CO₂ reduction to methane (CH₄) is a promising route for sustainable energy conversion and carbon neutrality. However, limited control over intermediates and competition from the hydrogen evolution reaction (HER) restrict selectivity and efficiency. To address these challenges, a ferrocene-based bimetallic metal-organic framework MOF catalyst (Ni_xIn_y-Fc/NF) with a hierarchical nanoflower architecture is developed, where dual-metal synergy modulates the electronic structure at active sites. Incorporating redox-active ferrocene units and optimizing the Ni/In ratio enhances active-site accessibility and tunes the electronic environment. Structural and compositional analyses, including scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), confirm that Ni₅In₃-Fc/NF possesses a 3D porous nanoflower morphology, while X-ray photoelectron spectroscopy (XPS) reveals electronic interactions between Ni and In. Electrochemical tests show that the catalyst achieves 76% CH₄ Faradaic efficiency at -0.8 V versus RHE and suppresses H₂ evolution. Ni₅In₃-Fc/NF maintains stability and CH₄ selectivity over 16 000 s of electrolysis. Density-functional theory (DFT) indicates that the bimetallic interface reduces the energy barrier for the rate-limiting *CO formation step, thereby accelerating the CO₂-to-CH₄ pathway. This study presents a synergistic strategy integrating dual-metal interaction and structural precision to enhance performance and durability in CO₂ electroreduction, offering insights into the rational design of high-performance MOF catalysts.