Fig. 2. FT-IR spectra of Co-MOF-based ZIF-67, prepared with (a) different Hmim/Co²⁺ molar proportions, Hmim (2-methylimidazolate), HC₁(1.5), HC₂(2), HC₃(6), and HC₄(16) (b) different solvents, SO₁ (methanol), SO₂ (ethanol), SO₃ (water), SO₄ (methanol–water), SO₅ (ethanol–water).