1 research outputs found
Toward a Comprehensive Understanding of Enhanced Photocatalytic Activity of the Bimetallic PdAu/TiO<sub>2</sub> Catalyst for Selective Oxidation of Methanol to Methyl Formate
Photocatalytic
selective oxidation of alcohols over titania supported with bimetallic
nanoparticles represents an energy efficient and sustainable route
for the synthesis of esters. Specifically, the bimetallic PdAu/TiO<sub>2</sub> system was found to be highly active and selective toward
photocatalytic production of methyl formate (MF) from gas-phase methanol.
In the current paper, we applied the electronic structure density
functional theory method to understand the mechanistic aspects and
corroborate our recent experimental measurements for the photocatalytic
selective oxidation of methanol to MF over the PdAu/TiO<sub>2</sub> catalyst. Our theoretical results revealed the preferential segregation
of Pd atoms from initially mixed PdAu nanoclusters to the interface
of PdAu/TiO<sub>2</sub> and subsequent formation of a unique structure,
resembling a core@shell architecture in close proximity to the interface.
The analysis of the calculated band gap diagram provides an explanation
of the superior electron–hole separation capability of PdAu
nanoparticles deposited onto the anatase surface and hence the remarkably
enhanced photocatalytic activity, in comparison to their monometallic
counterparts. We demonstrated that facile dissociation of molecular
oxygen at the triple-point boundary site gives rise to in situ oxidation
of Pd. The in situ formed PdO/TiO<sub>2</sub> is responsible for total
oxidation of methanol to CO<sub>2</sub> (no MF formation) in the gas
phase. Our investigation provides theoretical guidance for designing
highly selective and active bimetallic nanoparticlesî—¸TiO<sub>2</sub> catalysts for the photocatalytic selective oxidation of methanol
to MF