Polydopamine assisted synthesis of ultrafine silver nanoparticles for heterogeneous catalysis and water remediation

Abstract

Highly dispersed and ultrafine silver nanoparticles were synthesized on sepiolite nanofibres with polydopamine (Spl-PDA-Ag) and polyethyleneimine grafted polydopamine layers (Spl-PDA–PEI-Ag). The synthesized catalysts were thoroughly characterized to establish their chemical, structural, surface area, and morphology. The prepared catalysts were used for nitrophenol reduction and dye degradation in presence of sodium borohydride. Both catalysts showed exceptionally high catalytic efficiency for nitrophenol reduction with rate constants as high as 28.9 ×10−3 s−1 with turn over frequency 330 h−1. The Crystal violet and Methyl orange degradation performance was also considerably high with rate constant 6.6/7.3×10−3 s−1 and 6.5/7.1 ×10−3 s−1 for Spl-PDA-Ag and Spl-PDA–PEI-Ag, respectively. The high catalytic performance were obtained due to the synergistic effect of PDA/PEI layer with Ag nanoparticles. Apart from high catalytic activities, both catalysts show a very mild decrease in activity for over ten cycles of continuous reusability study, indicating their robustness and nonleaching from the substrates.