Effect of atomic layer deposited zinc promoter on the activity of copper-on-zirconia catalysts in the hydrogenation of carbon dioxide to methanol

The development of active catalysts for carbon dioxide (CO₂) hydrogenation to methanol is intimately related to the creation of effective metal-oxide interfaces. In this work, we investigated how the order of addition of copper and zinc on zirconia influences the catalytic properties, the catalytic activity and selectivity toward methanol. Regarding the carbon dioxide conversion and methanol production, the catalysts on which the promoter (zinc) was atomically deposited after copper impregnation (i.e., ZnO/Cu/ZrO₂ and ZnO/Cu/ZnO/ZrO₂) were superior catalysts compared to the reverse copper-after-zinc catalyst (Cu/ZnO/ZrO₂). Temperature-programmed experiments and in situ diffuse reflectance infrared Fourier transform-spectroscopy (DRIFTS) experiments allowed us to elucidate the benefits of the zinc-after-copper pair to store CO₂ as carbonate species and further convert them into formate species, key intermediates in the formation of methanol. This research provides insights into the potential of atomic layer deposition in the development of tailored heterogeneous catalysts for efficient CO₂ valorization to methanol.