The direct conversion of carbon dioxide (CO2) into methanol via hydrogenation is essential for industrial applications. Recent studies on catalysts that contain an inverse oxide/metal configuration have shown very good catalytic performance for the CO2 hydrogenation to methanol process. In this study, we investigated the behavior of indium oxide-Cu(111) interfaces under pure CO2 and CO2/H2 mixtures by using synchrotron-based ambient-pressure X-ray photoelectron spectroscopy (AP-XPS). Initially, a single layer of copper oxide (CuxO) was grown on the Cu(111) surface by controlled oxidation. On this surface, indium was deposited at room temperature. Oxygen atoms are transferred from CuxO/Cu(111) to the indium metal upon deposition, forming In-O-Cu bonds and active interfaces. Although Cu(111) is not very active for the binding and activation of CO2, the formed InOx-Cu(111) interfaces had no problem adsorbing and dissociating the molecules at room temperature. The reaction of CO2 with H2 on InOx-Cu(111) yielded surface-bound H3CO, CO2δ-, CO3, and CHx species, which are typical intermediates in the production of methanol and other oxygenates. The InOx-Cu(111) interface underwent dynamic chemical changes under reaction conditions, forming In-Cu alloys at low indium coverages (<0.05 monolayer), while at higher indium coverages, a mixture of In-Cu and InOx was detected in XPS. These findings indicate that InOx/In-Cu interfaces can play a key role in processes aimed at the trapping and valorization of CO2.
Keywords: CO2 activation; copper; indium oxide; indium oxide−copper interfaces; methanol production.