New Insights into CO Adsorption on TiO₂(110): Enhanced IRAS characterization

Abstract

TiO2(110) serves as a model system for investigating surface reactivity and catalytic behavior, with CO adsorption commonly employed as a probe molecule. While previous IR spectroscopy studies identified two distinct adsorption sites for low coverages (≤ 0.3 ML), regular Ti sites, and Ti sites near oxygen vacancies12, recent work based on DFT and microscopy suggests the existence of additional adsorption configurations influenced by the polaronic nature of the substrate3. In this contribution, we present experimental results obtained using our custom-built reactivity and infrared reflection absorption spectroscopy (IRAS) setup4. This design, optimized for detecting small concentrations of adsorbates on metal oxide surfaces, delivers high-resolution spectra with a high signal-to-noise ratio, allowing us to observe new features. Our data reveal multiple CO adsorption configurations on TiO2(110), which agrees with STM observations from a recent study3. Additionally, these results demonstrate the potential of IRAS to guide and validate theoretical approaches.