NiO-doped Au/Ti-powder: A catalyst with dramatic improvement in activity for gas-phase oxidation of alcohols

• NiO-doped Au/Ti-powder catalyst is highly active for gas-phase oxidation of alcohols.
• The catalyst shows good stability in longer-term test of alcohol oxidation.
• Formation of the NiO@Au ensembles is essential to the high activity.
• Ni2O3-Au+ was defined as active-site for the selective oxidation of alcohol.

An active and stable NiO@Au/Ti-powder catalyst, which can be obtained by doping Au/Ti-powder (Au: 35–40 nm) with NiO, has been developed for the gas-phase oxidation of alcohols. Gold particles are found to be partially covered with tiny NiO segments to form specific NiO@Au ensembles thereby leading to a dramatic conversion improvement from only ∼5% (without NiO doping) to ∼94% for the benzyl alcohol oxidation at 280 °C. Additionally, the selective oxidation of cyclopropyl carbinol can proceed over this catalyst at 280 °C with a selectivity of 94% and a conversion of 72–80% throughout the entire 300 h test. The hybrid active-sites, Ni2O3-Au+, on the NiO@Au ensemble are identified using X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS).

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