Enhanced Reducibility of the Ceria–Tin Oxide Solid Solution Modifies the CO Oxidation Mechanism at the Platinum–Oxide Interface

Many important catalytic reactions take place at metal–oxide interfaces. However, their mechanisms are typically difficult to probe due the low concentration of active sites and lack highly sensitive spectroscopic methods. In this work, we analyze impact oxide reducibility on mechanism low-temperature CO oxidation over platinum nanoparticles supported ceria-based solid solutions. We demonstrate that easier Ce4+ Pt/Ce0.5Sn0.5O2 interface (in comparison for Pt/CeO2) increases rate, lowers apparent activation energy, reaction order in oxygen. Operando time-resolved X-ray absorption spectroscopy suggests reduction rate is accelerated, while Ce3+ becomes rate-limiting. Importantly, no Sn4+ ceria–tin solution formation Pt/Sn alloys were detected under relevant conditions using situ spectroscopy, ambient-pressure photoelectron infrared spectroscopy. This work provides a better understanding reactivity It demonstrates close metal strongly influences rates, which ideas design catalysts.