Precursor concentration effects on crystallite size and enzyme immobilization efficiency of Enzyme@ZIF-8 composite

•ZIF-8 forms via an amorphous phase composed of precursors and enzyme.•ZIF-8 cannot form without enzymes at low molar ratio of precursors (Hmim/Zn).•Enzymes reversed correlation between the ZIF-8 size and the precursor molar ratio.•pH-dependent coordination state of Zn ion affects ZIF-8 formation via an amorphous phase.•Low molar ratio precursors efficiently immobilize enzymes in ZIF-8.