Controllable synthesis of mussel-inspired catechol-formaldehyde resin microspheres and their silver-based nanohybrids for catalytic and antibacterial applications

In this work, catechol-formaldehyde resin (CFR) microspheres were successfully prepared by a solvothermal method under alkaline conditions. Furthermore, the impacts of the concentration, solvent ratio and temperature on the size and morphology of the as-synthesized CFR microspheres were studied in detail. The results showed that the size of the CFR microspheres could be controlled between 50 and 800 nm by changing the reaction conditions, and the morphology of the CFR microspheres was significantly different under different conditions. The as-prepared CFR microsphere as a support was also used to construct a CFR-stabilized Ag nanoparticle (CFR@Ag) nanohybrid via an in situ reduction and growth process on mussel-inspired CFR layers. Upon alkaline solution treatment on the CFR microspheres, silver nanoparticles could be deposited onto the surface or inside of the CFR microspheres. Additionally, the abundant hydroxyl groups on the CFR spheres could act as reducing agents for both the Ag+ precursor and ligands to stabilize Ag NPs without additional reducing agents. The as-prepared CFR@Ag and alkali-treated CFR microsphere stabilized Ag NP (TCFR@Ag) nanohybrids could serve as highly efficient nanocatalysts for the reduction of 4-nitrophenol and methylene blue (MB) dye with good cycling stability. In addition, the nanohybrids as outstanding antibacterial agents also showed long-term inhibition of microbial growth against bacteria Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus).