Catalyst Engineering for the Selective Reduction of CO2 to CH4; A First-Principles Study on X-MOF-74 (X = Mg, Mn, Fe, Co, Ni, Cu, Zn)

The conversion of carbon dioxide (CO2) into more valuable chemical compounds represents a critical objective for addressing environmental challenges and advancing sustainable energy sources. The CO2 reduction reaction (CO2RR) holds promise for transforming CO2 into versatile feedstock materials and fuels. Leveraging first-principles methodologies provides a robust approach to evaluate catalysts and steer experimental efforts. In this study, we examine the CO2RR process using a diverse array of representative cluster models derived from X-MOF-74 (where X encompasses Mg, Mn, Fe, Co, Ni, Cu, or Zn) through first-principles methods. Notably, our investigation highlights the Fe-MOF-74 cluster's unique attributes, including favorable CO2 binding and the lowest limiting potential of the studied clusters for converting CO2 to methane (CH4) at 0.32 eV. Our analysis identified critical factors driving the selective CO2RR pathway, enabling the formation CH4 on the Fe-MOF-74 cluster. These factors involve less favorable reduction of hydrogen to H2 and strong binding affinities between the Fe open-metal site and reduction intermediates, effectively curtailing desorption processes of closed-shell intermediates such as formic acid (HCOOH), formaldehyde (CH2O), and methanol (CH3OH), to lead to selective CH4 formation.