Oxygen-rich Ti1−xO2 pillar growth at a gold nanoparticle-TiO2 contact by O2 exposure

In-situ gas-injection transmission electron microscopy revealed that a pillar grew at the edge of the interface of a gold nanoparticle and a TiO2 substrate during exposure to O2 gas at 100 Pa. The pillar was found to have a titanium-deficient chemical composition of Ti1 − xO2 (x > 0) by electron energy loss spectroscopy (EELS). The spectra showed a chemical shift of oxygen and titanium ions to have ionic states of Ti3+ and Oy− (y < 3/2). The formation of the Ti1 − xO2 at the contact edge of gold-Ti1 − xO2 interface is discussed from the perspective of an O2 affinity, which plays an important role in CO oxidation process of supported gold particle.