Efficient non-volatile organogold complex for TiO₂-supported gold cluster catalysts: Preparation and catalytic activity for CO oxidation

Gold nanoparticles supported on titania (Au/TiO₂) catalysts were prepared by solid grinding (SG) method using a halide-free nonvolatile organogold complex, bis(phenyl)boroxinato(4-tolylpyridyl)gold(III), abbreviated as AuBO, followed by calcination. Density functional theory (DFT) calculation revealed that AuBO was adsorbed on TiO₂ by hydrogen bonding with the surface hydroxy group of TiO₂ and that the adsorption energy was lower than those of other gold precursors. The obtained catalyst (AuBO/TiO₂) showed higher catalytic activity for CO oxidation than did Au/TiO₂ prepared by conventional deposition–precipitation method and by SG using other organogold complexes. Furthermore, grinding of the gold precursor with potassium tert-butoxide followed by calcination (AuBO/K-TiO₂) improved the catalytic activity and 100% CO conversion reached at − 23 °C (temperature at which 50% CO conversion occurs, T_1/2 = − 39 °C) as compared to AuBO/TiO₂ (T_1/2 = − 28 °C). Potassium tert-butoxide facilitated the decomposition of AuBO adsorbed on TiO₂, and increased surface basicity contributed to the improved catalytic activity. AuBO/K-TiO₂ also exhibited high catalyst stability for CO oxidation at room temperature.