Abstract
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•A gas-dependent sintering behavior of Au-TiO2 catalyst was visualized by in situ TEM.•Distinct sintering behaviors were observed under CO, O2 and CO/O2 mixed atmospheres.•The mechanisms were revealed through Cs-corrected STEM study.
Gas-involved sintering of supported nanoparticles is a common process of catalysts deactivation, but the mechanism is still ambiguous. Herein, we investigated the sintering behaviors of a Au-TiO2-(1 0 1) model catalyst in different gas environments via in situ environmental transmission electron microscopy (ETEM), spherical aberration (Cs-) corrected scanning transmission electron microscopy (STEM) and ex situ annealing experiments. Distinct sintering behaviors of Au-TiO2 catalysts were observed in ETEM that O2 or O2/CO mixed atmospheres facilitated but CO inhibited the sintering process. Ex situ annealing experiments were in accordance with in situ results. Further study with Cs-corrected STEM showed that TiO2 support annealed in CO got rougher and more defective than that annealed in O2, which suppressed the free movement of Au particles on TiO2 surface.