Facile fabrication of a biomass-based film with interwoven fibrous network structure as heterogeneous catalysis platform.

The stable and efficient immobilization of silver nanoparticles (AgNPs) on/into processable biomass-based macro-support with porous networks is a promising and sustainable strategy to achieve both high catalytic activity and excellent reusability for heterogeneous catalysis. In this work, a collagenic composite film was facilely fabricated at room temperature, via the self-assembly of natural collagen fibers (CFs) and gallic acid modified silver nanoparticles (GA@AgNPs) induced by chromium (III) cross-linking in water. The morphology and microstructure of such GA@AgNPs-Cr-CFs composite film was investigated by Scanning Electron Microscope (SEM) and X-ray Photoelectron Spectroscopy (XPS), respectively. The results revealed that the cross-linking based on the coordinated complexation between chromium ions (Cr3+) and carboxyl groups on CFs and GA@AgNPs played the critical role in the interwoven of collagen fibers, leading to a three dimensional (3D) interconnected porous network of the composite film with simultaneously incorporation and high payload of silver nanoparticles. Furthermore, this GA@AgNPs-Cr-CFs composite film exhibited excellent catalytic activity toward the reduction of 4-nitrophenol (4-NP), taking the advantage of its high specific surface area given by the interwoven fibrous network structure. More than that, such sustainable composite catalyst could be easily recovered and reused for ten cycles because of its high stability based on cross-linking. This catalytic platform constructed by natural fibers, noble metal nanoparticles and trivalent metal ions showed a sustainable avenue for heterogeneous catalytic system.