Au₉ clusters deposited as co-catalysts on S-modified mesoporous TiO₂ for photocatalytic degradation of methyl orange

Au₉ nanoclusters (Au₉ NCs) were deposited onto S-functionalized mesoporous TiO₂ (SMTiO₂) to produce efficient photocatalysts for Methyl Orange (MO) dye degradation with UV light. The morphology, the surface composition and the size of the deposited Au₉ NCs of the catalyst was analysed. SMTiO₂ could adsorb more clusters with lesser Au₉ cluster agglomeration than unmodified MTiO₂. This finding is attributed to the capability of the thiol groups to form strong bonds with the Au₉ clusters. To study Au₉ NCs effect on dye degradation activity, the MO degradation reaction constants under UV-light irradiation for SMTiO₂ nanoparticles (NPs) and Au₉ NCs decorated SMTiO₂ photocatalysts were studied, which were 0.07 min⁻¹ and 0.149 min⁻¹, respectively. Hence, it takes almost half the time to completely degrade MO using Au₉ NCs decorated SMTiO₂ photocatalysts compared to SMTiO₂ substrate. Results were analysed using the response surface methodology (RSM) to study the interaction between the reaction parameters.