Harnessing Coordination Microenvironment of Metal-bis(dithiolene) Sites for Modulating Electrocatalytic CO₂ Reduction...

Nature's metalloenzymes inspire biomimetic catalysts for the CO₂ reduction reaction (CO₂RR), particularly using metal-bis(dithiolene) ([MS₄]) cores in frameworks. While prior research focused on tuning the chelating atoms of Ni-centered sites or [NiS₄] in metal-organic frameworks (MOFs), how different metal centers affect the electronic structure and catalytic activity is often overlooked. Notably, reported [NiS₄] molecular analogues exhibits a Faradaic efficiency (FE) of less than 70% for the major carbon product and shows operational stability for only about 4 hours (say falling FE and current density beyond). In this study, MOFs are used to host [MS₄] units with varying central metals (M = Ni, Cu, Co, Fe) to assess how the metal center affects electrocatalytic CO₂RR. Among the studied MS₄-In MOFs, NiS₄-In demonstrates the best performance, achieving a FE_CO of 88.54% and operational stability greater than 6 hours-significantly outlasting the ≈200 seconds of the [NiS₄] molecule. This work underscores the importance of frameworks in stabilizing [MS₄] units and highlights [MS₄] as essential for CO₂ binding and reduction, with [NiS₄] exhibiting optimal catalytic performance due to its favorable electronic properties. This findings clarify how substituting the metal center within the framework enhances electronic structure and coordination, leading to improved electrocatalytic performance.