Polydopamine microcapsules loaded Ag nanoparticles for catalytic reduction of organic pollutants

We demonstrate a simple approach for fabricating polydopamine microcapsules decorated with silver nanoparticles (Ag@PDA MCs) as highly efficient catalysts for water purification. Polydopamine microcapsules (PDA MCs) were formed on the MnCO3 template from self-polymerization and the removal of template under mild EDTA solution, followed by in situ reduction of Ag+ by PDA and growth of monodispersed Ag nanoparticles. Under optimized conditions, the Ag@PDA MCs exhibits 41.56 wt% of Ag loading contents and superior catalytic performance for the degradation of organic pollutants with rate constant of 2.93 min-1 for methylene blue and 1.03 min-1 for 4-nitrophenol. The excellent catalytic activity can mainly be ascribed to high surface roughness of microcapsules, high Ag loading ratio, and uniform distribution of Ag nanoparticles. In addition, this catalyst can be recycled for five times with degradation efficiency higher than 98%. The Ag@PDA MCs possessed fast reduction rate, high catalytic activity, and good recyclability as well as facile preparation and easy separation, showing great potential for the application in wastewater treatment.