Elucidating water’s place in catalytic C3H6 combustion over Pt@TiOx/TiO2 with super-hydrophilic silica-modified surface

In order to find out the reasons behind the steam-accelerated C3H6 combustion over supported platinum, a Pt@TiOx/TiO2 catalyst modified by silica (Pt@TiSi) with “super-hydrophilic” surface and metallic platinum sites was synthesized in the present study. In situ spectroscopy analyses excluded the structural change of platinum during reactions, suggesting water has to be involved chemically to accelerate the reactions. By comparing the water response and kinetics of the silica-modified and unmodified samples, a water-mediated O2 adsorption and activation pathway (HOH···OO* → OOH*) was identified as the origin of the activity bonus induced by steam. Since OOH* formed readily at the interface between platinum and the hydrophilic supports (e.g., TiOx-SiO2), Pt@TiSi exhibited drastically enhanced C3H6 oxidation activity in the presence of moisture. Collectively, this work provides an extensible example about how to fabricate efficient catalysts for reactions with positive H2O rate orders, and how to unveil the water effects behind them.