SEM images of the ramified Cu aggregates and nanocrystals on ionic liquid surfaces, f = 0.005 nm/s. (a) The morphology of the ramified Cu aggregate, and the inset is the high-resolution SEM image of the rectangle region, d = 0.3 nm. (b) The morphologies of the Cu granules and nanocrystals, d = 3.0 nm. (c) The morphologies of the Cu granules and nanocrystals, and the inset shows the side view of a nanocrystal with triangular appearance, d = 4.0 nm.