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 CO2 to more value-added chemicals stands as a critical goal for addressing environmental concerns and fostering sustainable energy sources with the CO2 reduction reaction (CO2RR) holding promise in converting CO2 into versatile feedstocks and fuels. First-principles methodologies offer a powerful approach to assess catalysts and inform experimental pursuits. We investigate CO2RR on diverse representative models of X-MOF-74 (X = Mg, Mn, Fe, Co, Ni, Cu, Zn) using first-principles methods. Our analysis reveals favorable CO2 adsorption exclusively on the Fe-MOF-74 surface. Intriguingly, the electrochemical energy needed to reduce CO2 to CH4 (0.32 eV) is minimized on the Fe open-metal site. Crucial determinants for selective CO2RR leading to CH4 formation on the Fe-MOF-74 surface emerge, encompassing unfavorable hydrogen reduction to H2, coupled with strong binding of all reduction intermediates to suppress undesired desorption of other reduced CO2 products.