Fig. 7
From: Effect of Mn2+ concentration on the growth of δ-MnO2 crystals under acidic conditions
TEM images of δ-MnO2 react with 25 mM Mn2+ at pH 4 about 12 h (a and b), and 4 d (c and d). The yellow lines show the assembly of δ-MnO2 nanoflakes on the end of nanoribbons in image d