Fig. 1. Mechanism diagram of amidoxime preparation by cyano-hydroxylamine method

Fig. 2. Amide (thioamide) -hydroxylamine method preparation-AO typical material^[21]

Fig. 3. Preparation of amidoxime functionalized ZIF-90-AO^[31]

Fig. 4. Reaction mechanism of PAO alkali treatment^[45]

Fig. 5. Schematic illustration of the synthesis of In-N_x-C-R^[70]

Fig. 6. (a) Structure of amidoxime-functionalized layered porous polymer^[56]; (b) diagram of U(VI) adsorption on PAN-NH₂-AO^[17]

Fig. 7. Adsorption mechanism of MIL-101-SMA-AO^[83]

Fig. 8. Three nucleophilic centers of amidoxime group^[88]

Fig. 9. Coordination modes of amidoxime ligands with metal ions^[89]