The Interplay between Structure and Product Selectivity of CO2 Hydrogenation

Identification of the active structure under reaction conditions is of great importance for the rational design of heterogeneous catalysts. However, this is often hampered by their structural complexity. The interplay between the surface structure of Co3O4 and the CO2 hydrogenation is described. Co3O4 with morphology-dependent crystallographic surfaces presents different reducibility and formation energy of oxygen vacancies, thus resulting in distinct steady-state composition and product selectivity. Co3O4-0 h rhombic dodecahedra were completely reduced to Co-0 and CoO, which presents circa 85 % CH4 selectivity. In contrast, Co3O4-2 h nanorods were partially reduced to CoO, which exhibits a circa 95 % CO selectivity. The crucial role of the Co3O4 structure in determining the catalytic performance for higher alcohol synthesis over CuCo-based catalysts is demonstrated. As expected, Cu/Co3O4-2 h shows nine-fold higher ethanol yield than Cu/Co3O4-0 h owing to the inhibition for methanation.