Facile one-pot synthesis of sodium alginate-silica anchored MOF-199 sponge-like porous composites: sustainable catalysts for efficient reduction of 4-nitrophenol

A sustainable one-pot co-condensation strategy was developed for the fabrication of sodium alginate (SA)-silica hybrid carriers (SA-SiO 2 ), via the covalent cross-linking via carboxyl and hydroxyl groups. The SA-SiO 2 matrix was used as a bio-based platform to immobilize Cu 2+ ions via carboxyl coordination, enabling in situ growth of MOF-199 crystals (denoted as MOF-199@xSA-SiO 2 ). FT-IR, XPS, and UV–vis demonstrated the successful cross-linking of SA with SiO 2 , the effective loading of MOF-199 through −COOH in the SA matrix, and the strong interaction between the carrier SA-SiO 2 and MOF-199. Additionally, SEM and N 2 adsorption-desorption analyses showed that the MOF-199@xSA-SiO 2 composites exhibited a spongy pore structure and possessed a typical mesoporous structure. The [email protected] 2 composite exhibited good catalytic activity in the reduction of 4-NP to 4-AP. Under optimal reaction conditions, the K app of the 4-NP reduction reaction was 0.45 min −1 . In contrast, the MOF-199/0.15SA-SiO 2 composite that was prepared using a post-synthesis method achieved a K app of only 0.11 min −1 . The catalyst maintained 98.23 % conversion of 4-NP five cycles, demonstrating good catalytic activity and stability. This study highlights the dual roles of SA as a porous guide and a metal ligand site, providing a green pathway for designing polysaccharide-MOF complexes for efficient environmental catalysis.