Theoretical Prediction of Electrocatalytic Reduction of CO Using a 2D Catalyst Composed of 3 d Transition Metal and Hexaamine Dipyrazino Quinoxaline.

Transition metals and organic ligands combine to form metal-organic frameworks (MOFs), which possess distinct active sites, large specific surface areas and stable porous structures, giving them considerable promise for CO reduction electrocatalysis. In the present study, using spin polarisation density-functional theory, a series of 2D MOFs constructed from 3d transition metal and hexamethylene dipyrazoline quinoxaline(HADQ) were investigated. The calculated binding energies between HADQ and metal atoms for the ten TM-HADQ monolayers were strong sufficient to stably disperse the metal atoms in the HADQ monolayers. Of the ten catalysts tested, seven (Sc, Ni, Cu, Zn, Ti, V and Cr) exhibited high CO reduction selectivity, while Mn, Fe and Co required pH values above 2.350, 6.461 and 6.363, respectively, to exhibit CO reduction selectivity. HCOOH was the most important producer for Sc, Zn, Ni and Mn, while CH was the main producer for Ti, Cr, Fe and V. Cu and Co were less selective, producing HCHO, CH OH, and CH simultaneously at the same rate-determining step and limiting potential. The Cu-HADQ catalyst had a high overpotential for the HCHO product (1.022 V), while the other catalysts had lower overpotentials between 0.016 V and 0.792 V. Thus, these results predict TM-HADQ to show excellent activity in CO electrocatalytic reduction and to become a promising electrocatalyst for CO reduction.