In situ copper nanoparticle immobilization on the indigo carmine-functionalized chitosan: a versatile biocatalyst towards CO2 fixation and click reactions in water

For catalyst construction, biopolymeric chitosan has attracted the interest of many researchers due to its biodegradability and economic viability. Accordingly, this study utilized chitosan as a green support to produce a versatile heterogeneous catalytic system. Chitosan was first functionalized with indigo carmine (IC) and then metal nanoparticles (i.e., Cu2O and CuO) were immobilized on the IC-functionalized chitosan (IC-CS). The successful synthesis process was fully confirmed using different techniques such as SEM, FT-IR, EDX, XRD, TGA, and DTG. After ensuring catalyst fabrication, the catalytic activities of Cu2O/IC-CS and CuO/IC-CS were investigated for the oxidation state of copper in the click reaction and CO2 fixation, respectively. The obtained results revealed the application of these biocatalysts in the above-mentioned reactions with water as a green solvent in the shortest time with high efficiency and selectivity for the desired products. © 2023 The Royal Society of Chemistry.