Finally, the FT-IR spectrum results of CSGO-metal ions are shown in Fig. 1B indicated that the intensity of the peaks at about 3430 cm−1, 1659 cm−1 and 1591 cm−1 changed and even some peaks disappeared compared to the peaks of CSGO, which might suggest the chemical reaction between previous metals and the functional groups, such as NH2, OH, COOH, and C=C groups.