CO₂ hydrogenation to methanol has attracted increasing attention with the development of renewable hydrogen. Here we report an In₂O₃ supported Au catalyst that exhibits excellent performance for hydrogenation of CO₂ selectively to methanol. In-situ characterizations using time-resolved X-ray diffraction (TR-XRD), ambient-pressure X-ray photoelectron spectroscopy (AP-XPS), and X-ray absorption spectroscopy (XAS) confirm that a strong metal-support interaction leads to a reactive Au^δ+-In₂O_3-x interface for activation and hydrogenation of CO₂ to methanol. An effective gold-indium oxide bonding favors the dispersion of the noble metal and prevents its sintering under reaction conditions. The methanol selectivity reaches 67.8% at 300 °C with a space time yield (STY) of methanol of 0.47 g_MeOH/(h g_cat). The strong metal-support interaction was also confirmed theoretically by performing density functional theoretical (DFT) calculation on a Au₄/In₂O₃ model catalyst. This interaction causes the electron redistribution at the interfacial sites and leads to a positively charged Au^δ+ cluster instead of metallic Au⁰, consisting with the in-situ characterization results. This electron redistribution facilitates the methanol synthesis by several ways: leading to an active and positively charged Au₄ cluster for H₂ dissociation; providing Au-In₂O₃ interfacial sites for CO₂ activation and intermediates to be hydrogenated to methanol; and benefiting the removal of hydroxyl to prohibit the catalyst deactivation. All these effects account for the fact that Au/In₂O₃ catalyst is a promising candidate for the methanol synthesis from CO₂ selective hydrogenation. Our study shows that the strong Au-In₂O₃ interaction and the intrinsic chemical activity of In₂O₃ can be used to significantly improve the catalytic performance of Au catalysts, providing promising routes for the rational design and application of Au catalyst beyond CO₂ hydrogenation.

Changjun Liu

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