Green synthesis of Janus hydrogel beads including Ag nanodendrites and their application

Abstract

Janus hydrogel beads including silver (Ag) nanodendrites were synthesized by injecting the aqueous sodium-alginate (Na-alginate) droplets in the aqueous silver nitrate (AgNO₃) solution. Then, Na-alginate could be ionically crosslinked by Ag⁺ ions, and Ag⁺ ions could be reduced by alginate under sunlight irradiation to form hydrogel beads containing Ag nanodendrites. Specifically, Ag nanodendrites were selectively formed on one side of the beads exposed to light, and only one side of the beads turned brown to form a Janus shape. When the Janus hydrogel beads were used as catalytic microreactors for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by sodium borohydride (NaBH₄), they exhibited outstanding catalytic activity and excellent reusability.

Keywords:

• Alginate
• heterogeneous catalyst
• hydrogel
• Janus bead
• silver dendrite

Additional information

Funding

This work was supported by the Pukyong National University Research Fund in 2019 (CD20191250).