Unraveling the Methanol Oxidation Mechanism over a Titania-Supported Platinum Catalyst

The development of noble metal catalysts with sustained high activity for methanol oxidation is essential for chemical production and for energy transformation with methanol fuel cells. Here, we report Pt oxide clusters supported on anatase TiO2, exhibiting enhanced methanol oxidation performance. Interfacial interactions between oxidized Pt clusters and TiO2 strongly influence electronic states and adsorption of intermediates, thereby shaping catalytic performance. Density functional theory (DFT) combined with Fourier-transform infrared spectroscopy (FTIR) revealed methanol adsorption and oxidation mechanisms. Using grand canonical basin hopping (GCBH), we identified stable and metastable model Pt6Ox clusters on TiO2(101), with Pt6 partially oxidized to Pt6O10 under ambient conditions. Three methanol oxidation pathways were examined: partial oxidation to CO, formation of methyl formate (HCOOCH3) by C–O coupling, and complete oxidation to CO2, proceeding via the *OCH2O (dioxymethylene DOM) intermediate. The formation of DOM enables an alternative pathway in which the C–O bond forms at an early stage, thus offering a CO-free mechanism that prevents CO poisoning. The Pt oxide cluster exhibits dynamic redox behavior, undergoing initial partial reduction followed by reoxidation, highlighting the adaptive nature of the catalytic system. Notably, the catalytic activity is further enhanced when water formation accompanies the reaction pathway. Overall, this work provides insight into how the Pt/TiO2 interface is the origin of a high methanol oxidation activity, consistent with experimental observations. These insights bring a rational framework for designing efficient and durable catalysts for selective oxidation reactions.