Facile immobilization of Ag nanoparticles on microchannel walls in microreactors for catalytic applications

The microreactor technologies have shown great potential in heterogeneous catalysis reactions. Nevertheless, the integration of catalysts inside microreactors often suffer from several challenges such as troublesome procedure, instable immobilization and low catalytic activity thus limiting the wide utilization of microreactors in catalysis. Herein, a facile and efficient strategy, which is assisted with the versatile adhesion and reduction properties of polydopamine coating, has been proposed for simply and stably immobilizing catalysts of silver nanoparticles (Ag NPs) on the walls of microchannels in glass microreactors. The proposed approach is featured with the advantages of both chemical stability and physical simplicity. The whole fabrication procedure could be easily and quickly conducted under a mild environment. The formation of Ag NPs on the walls of microchannels could be simply tuned by varying the reduction temperature. In a demonstration reaction of 4-nitrophenol to 4-aminophenol, the microreactors immobilized with Ag NPs on the walls of microchannels show high catalytic activity and satisfactory stability during the continuous reaction for 24 h, which confirms the outstanding stability of the immobilized Ag NPs. The proposed strategy in this study provides a facile route for fabricating metallic nanocatalysts equipped microreactors. (C) 2016 Elsevier B.V. All rights reserved.