Spatially Resolved Understanding of Electronic Metal–Support Interactions on Cu/TiO 2 (110)

Electronic metal support interactions (EMSIs) play a significant role in heterogeneously catalyzed chemical transformations and result in charge transfer across the metal/support interface. In this work, the spatially resolved variations in the local density of states (LDOS) across Cu/TiO 2 (110) were determined using a combination of scanning tunneling microscopy (STM) and spectroscopy (STS). We found that, depending on the exact surface reconstruction of rutile TiO 2 (110) formed, there are subtle differences in the initial oxide LDOS in the valence region. STM analysis following submonolayer Cu deposition revealed the formation of morphologically distinct Cu nanoparticles. STS taken atop, adjacent to, and far from Cu nanoparticles confirmed that perturbations to the LDOS not only occur at the immediate metal/support interface but also radiate into the near-interfacial region surrounding the Cu particle. Notably, larger Cu nanoparticles had a wider perturbed near-interfacial region, illustrating how the degree of EMSI is correlated to nanoparticle size. These findings provide direct insight into how the presence and morphology of metal nanoparticles directly influence the electronic landscape of the oxide support. This electronic heterogeneity may indicate that near-interfacial surface sites, in addition to the interface itself, play a unique role in heterogeneously catalyzed chemical transformations due to the modified electronic properties of this near-interfacial region.