Bismuth-Supported Mesostructured Silica: Ligand-Directed Growth of Nanosheets for Sustainable Catalysis and Iodine Scavenging

Bismuth is widely recognized for its natural abundance, moderate cost, and low toxicity, making it an attractive alternative to the expensive and toxic transition metals commonly employed in heterogeneous catalysis. In this work, we report the immobilization of bismuth onto a series of SBA-15 materials and their application for nitrophenol reduction and iodine uptake. Particular attention was given to anchoring bismuth on three nitrogen-containing mesostructured silicas in comparison with its deposition on the unmodified silica support. Remarkably, nitrogen-containing ligands directed the nucleation and growth of crystalline bismuth nanosheets, whereas the pristine SBA-15 afforded atomically dispersed and amorphous metal particulates. Bismuth loaded on SBA-NNH2 represents an optimal balance between porosity, accessibility, and metal–ligand interaction. Crystalline nanosheets displayed interesting catalytic activity for the reduction of nitrophenol to the corresponding aromatic amine, even at low bismuth loading (kapp = 3.8 × 10−3 s−1), and exhibited recyclability. Upon reduction, bismuth loaded on SBA-NNH2 stands as the best scavenger for iodine adsorption, reaching 442 mg.g−1. On the whole, these findings highlight the role of the N-ligands in directing the growth of bismuth particles and the capability of the resulting bismuth-supported materials for iodine scavenging and for sustainable catalysis in fine and pharmaceutical chemistry.