Strong electrostatic adsorption of Pt over CoOx/TiO2 dual-support: Effect of synthesis pH on the catalytic activity for the CO oxidation in presence of hydrogen

Highly dispersed Pt-based catalysts were prepared by Strong Electrostatic Adsorption (SEA) for the PROX reaction. The effect of the catalyst synthesis pH was investigated to control the metal-support interactions for the system: Pt supported onto cobalt oxide, previously supported on TiO2. The Pt/CoOx/TiO2 catalysts were prepared in a pH range of 3.0–9.0, obtaining Pt dispersion values above 90% with Pt crystallite sizes of 1–2 nm. The effect of the synthesis pH was correlated with the concentration of (Pt-CoOx)i interfacial sites, and this, in turn, with the catalytic activity. The concentration of (Pt-CoOx)i interfacial sites was higher for the most active catalyst, which was prepared at a condition that ensures a higher selective-SEA of Pt over the co-support (pH = 6.0). This study shows that the synthesis pH can determine the concentration and type of active sites and paves the way to use SEA to control the activity of dual-supported catalysts.