Hydrogen-related defects in titanium dioxide at the interface to palladium

A metal oxide support and a catalytically active are the two main ingredients for complex catalysts used in heterogeneous catalysis. The gas environment can change catalyst during reaction, modifying its structural electronic properties. Here, we use monochromated electron energy loss spectroscopy (EELS) to reveal hydrogen-pressure-dependent changes of structure at Pd/rutile-TiO$_2$ interface an environmental transmission microscope (ETEM). Hydrogen-induced observed rutile-TiO$_2$ within $2$~nm from $10$~Pa hydrogen pressure, Ti $L_{3,2}$ EEL spectra. Lower pressures such as $1$~Pa show no We attribute spectra hydrogen-induced defects accumulating vicinity interface. Based on DFT calculations, developed thermodynamic multistate defect (TMD) model bulk rutile-TiO$_2$. This TMD predicts high concentrations positively charged presence Schottky barrier stabilizes these by significantly lowering their formation energy. Our findings provide important new insights into catalytic processes taking place metal/metal interfaces environments.