Fig. 4: Abrupt changes (transitions) of the THF hydrate nucleation activity of Ag/Au nanocubes at specific supercooling temperature ΔT_L which is determined by the size of nanoparticles L.

a–i The AFM images, corresponding height profiles through the cross-section along the marked lines of anchored nanocubes on the substrate, and TEM images of suspended nanocubes. 45 nm Ag nanocubes (a–c), 45 nm Au nanocubes (d–f), and 70 nm Au nanocubes (g–i), respectively. Scale bar of (a), (d) and (g) AFM images, 200 nm. Scale bar of (c), (f) and (i) TEM images, 100 nm. j The scaled delay time of nucleation of THF aqueous solution, τ = nt_D, versus ΔT. The three curves for each nanocube come from different n and collapse into the same curve. Black – 70 nm Au nanocube, red – 45 nm Au nanocube, blue – 45 nm Ag nanocube. The inset shows the L ΔT_L ≈ 450 nm °C for all the Au and Ag nanocubes. Magenta – 70 nm Au nanocube, cyan – 45 nm Au nanocube, orange – 45 nm Ag nanocube. Every average clathrate hydrate nucleation delay time shows mean ± SEM. The mean values were averaged from 36 measurements for the 70 nm Au nanocube with coverage of n = 0.16, 45 nm Au nanocube with coverage of n = 0.26, and Ag nanocube with coverage of n = 0.22. For the every other nanocube coverage, the mean values were averaged from 39 measurements. k The free-energy barrier of THF hydrate nucleation ΔG^* on the Ag/Au nanocubes in the unit of that on sufficient-large substrates ΔG^*_het. The free-energy barrier obtained from the data in Fig. 4j is compared with the theoretical calculation based on the spirit of CNT (orange line and axis, the transition occurs at \({l}_{{{{{{\rm{c}}}}}}}=\frac{L}{2{R}_{{{\mbox{c}}}}}\, \approx \, 0.8\) for the nanocubes with the side length L, see Supplementary Fig. 8). Black – 70 nm Au nanocube, red – 45 nm Au nanocube, blue – 45 nm Ag nanocube, orange – fit line and corresponding XY axis. Inset, schematic illustrations of the shapes of clathrate nucleus with various sizes on a nanocube. Every data point in (k) is processed from (j), and shows mean ± SEM. The mean values were averaged from 36 measurements for the 70 nm Au nanocube with coverage of n = 0.16, 45 nm Au nanocube with coverage of n = 0.26, and Ag nanocube with coverage of n = 0.22. For the every other nanocube coverage, the mean values were averaged from 39 measurements.