The bio-inspired heterogeneous single-cluster catalyst Ni100-Fe4S4 for enhanced electrochemical CO2 reduction to CH4.

Abstract

Electrochemical conversion of CO2-to-CH4 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 CH4 activity and selectivity remains a major challenge because the electrochemical reduction of CO2-to-CH4 is accompanied by various C1 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-Fe4S4 at the atomic level, which may show high CO2 electroreduction performance. Combined with the crystallographic data and theoretical calculations, Ni100-Fe4S4 and CO dehydrogenase exhibit highly similar catalytic geometric active centers and CO2 binding modes. By exploring the origin of the catalytic activity of this biomimetic structure, we found that the activation of CO2 on Ni100-Fe4S4 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 CO2 molecules efficiently and stabilize various intermediates in multistep elementary reactions to selectively produce CH4 at a low overpotential (0.13 eV). The calculated CO2 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.