Fig. 2
From: Self-activated surface dynamics in gold catalysts under reaction environments
Dynamic nature of a self-activating nanofacet on {110}. A nanofacet being a dynamic in CO/air (1 vol.% CO/air, 100 Pa) and b stable in O2 (100% O2, 100 Pa). Images are taken from in situ environmental transmission electron microscopy (ETEM) movies (frame rate: 40 fps) (Supplementary Movies 1 and 2). In a, white arrows indicate the top atomic column of the nanofacet, and gray arrows at 100, 200, and 900 ms indicate the absence of atoms at the top atomic column, or displaced to an adjacent site (out of view) (Supplementary Movie 1). Note that the image contrast of the top atomic column varied with time (from 400 to 800 ms) (see also Supplementary Note 4). Time-dependent distances between the top atomic column and the atomic column immediately below, D in c CO/air and d O2. D was evaluated by Gauss fitting for intensity profiles of ETEM images (Supplementary Note 2). The fitting errors are shown as error bars. In c, d, dotted bars represent the range of D in pure gold and Au–Ag nanofacet models without oxygen, while shaded areas represent those Au–Ag nanofacet models with oxygen (or Au–AgO models). e Distribution of D for time intervals of 100 ms in CO/air and O2. Arrows in e indicate the corresponding distance between Au and Au atomic columns in pure crystalline gold surfaces (DAu = 0.288 nm) and that between Au and Ag atomic columns in the nanofacet models (D = 0.2842–0.2849 nm) (Supplementary Note 5). In a, b, ETEM images at 0 and 900 ms are shown in full size, and those from 100–800 ms are shown partially in the area between the dotted lines at 0 ms. The image contrast and frame rate in Supplementary Movies 1 and 2 were adjusted with 4 × 4 × 4 binning. Scale bars: 0.5 nm
