Fig. 2: DFT prediction of facet and concentration-dependent stencilling.
a, Geometry-optimized structures in DFT calculations of 2-NAT adsorption without (top) and in the presence of (bottom) iodide on three low-index gold facets of (111), (100) and (110) at surface coverages of 1/2 ML for iodide and 1/3 ML for 2-NAT. Aromatic rings of 2-NAT are omitted for clarity in the top panel. 2-NAT molecules chemisorbed and physisorbed on gold are coloured orange and yellow, respectively. b, DFT calculation of dAu–S with increasing iodide coverage on each facet, at a fixed 2-NAT coverage of 1/3 ML. c, Contributions to 2-NAT binding energy (Eb) to each gold facet from chemisorption (grey bars) and physisorption (white bars) at a fixed 2-NAT coverage of 1/3 ML and increasing iodide coverages from left to right. d, The atomic ratio of Au and I in averaged line profiles across the iodide-incubated gold octahedron obtained from EDX (left). The gold octahedron is extensively washed after incubation to remove excess iodide from the solution. High-angle annular dark-field (HAADF) imaging and EDX mapping of the same gold octahedron (right). Scale bars, 20 nm. e, Phase diagram delineating equilibrium adsorption configurations on gold as a function of iodide and 2-NAT chemical potentials. The surface coverages of iodide (purple) and 2-NAT (orange) on three different facets are represented by relative line lengths (coverage values in Supplementary Table 13), corresponding to the numbered phase regions in the phase diagram. Regions in which stencil effect is predicted by DFT are shaded in cyan.
