Random alloy nanoparticles of Pd and Au immobilized on reducible metal oxides and their catalytic investigation

Well-dispersed, random alloy, palladium-gold nanoparticles (2.66 ± 0.51 nm) were immobilized onto several reducible mesoporous transition metal oxide materials. The composites (palladium-gold nanoparticles immobilized onto mesoporous transition metal oxide (PdAu–MTMO)) were characterized through several analytical methods such as UV–vis spectroscopy, BET, XRD, FT-IR, ICP-OES, TEM and TPR analyses. Catalytic oxidation of morin (quercetin) was performed as a model reaction in the presence of hydrogen peroxide to investigate the synergic catalytic activity of the composite. Silica was used as inert support to isolate the catalytic activity of the metal nanoparticles (32.69 ± 9.93 kJ mol⁻²). Synergistic interaction of PdAu–MTMO was mechanically described according to Langmuir-Hinshelwood and Mars-van Krevelen approaches. The TOF of PdAu–Co₃O₄ (6073.23 ± 85.01 s⁻¹ mol⁻¹) was considerably larger than that of random alloy nanoparticles (PdAu–SiO₂ (25.71 ± 2.35 s⁻¹ mol⁻¹)). The Arrhenius-type plot was constructed to determine the synergistic activity of the composite, where PdAu–Co₃O₄ described the best synergistic interaction.