The bio-inspired heterogeneous single-cluster catalyst Ni100-Fe 4 S 4 for enhanced electrochemical CO 2 reduction to CH 4 .

Electrochemical conversion of CO 2 -to-CH 4 is a process of converting the inert greenhouse gas into energy molecules. It offers great promise for the transformation of carbon-neutral economy. However, achieving high CH 4 activity and selectivity remains a major challenge because the electrochemical reduction of CO 2 -to-CH 4 is accompanied by various C 1 intermediates at the catalytic site, involving multiple proton-coupled electron transfer processes. Herein, different from the traditional designing strategy, we propose a bio-inspired theoretical design approach to construct a heterogeneous single-cluster catalyst Ni100-Fe 4 S 4 at the atomic level, which may show high CO 2 electroreduction performance. Combined with the crystallographic data and theoretical calculations, Ni100-Fe 4 S 4 and CO dehydrogenase exhibit highly similar catalytic geometric active centers and CO 2 binding modes. By exploring the origin of the catalytic activity of this biomimetic structure, we found that the activation of CO 2 on Ni100-Fe 4 S 4 theoretically exceeds that on natural CO dehydrogenase. Density functional theory calculations reveal that the dehydrogenase enzyme-liked Fe-Ni active site serves as an electron enrichment 'electro-bridge' (an electron-rich highly active catalytic site), which can activate CO 2 molecules efficiently and stabilize various intermediates in multistep elementary reactions to selectively produce CH 4 at a low overpotential (0.13 eV). The calculated CO 2 electroreduction pathways are well consistent with the nickel-based catalytic materials reported in experimental studies. Our work showcases and highlights the rational design of high-performance catalytic materials via the biomimetic methodology at the atomic level.