New insights on the electronic factor of the SMSI effect in Pd/TiO2 nanoparticles

[Display omitted] •The electronic factor dominates the low temperature regime of SMSI effect.•The electronic factor is mediated by O p states of Pd-O-Ti entities.•The electronic interaction occurs through charge transfer from Pd nanoparticles to TiO2.•The electronic interaction is enhanced with an oxidizing treatment. Whereas observed and explored for over 40 years, there are still open questions regarding the nature of the Strong Metal-Support Interaction (SMSI) effect. The lack of a precise determination of the atomic mechanisms of electronic and geometrical factors of the SMSI effect hinders the application of metal-support systems towards several catalytic reactions. The present study sheds light on the electronic factor of the SMSI effect in Pd/TiO2 nanoparticles by using Near Ambient Pressure Photoelectron Spectroscopy (NAP-XPS), Ultraviolet Photoelectron Spectroscopy (UPS), and Density Functional Theory (DFT) calculations. The electronic and geometrical factor of the SMSI effect were observed during reduction treatment at 300 °C and 500 °C, respectively. The results enable mapping the electronic factor during reduction treatment at 300 °C, where a charge transfer from Pd nanoparticles to TiO2 support through Pd-O-Ti entities existing at the Pd-TiO2 interface is observed. Furthermore, the charge transfer is mediated by O p states present at the Pd-TiO2 interface.