Janus colloid surfactant catalysts for in situ organic reactions in Pickering emulsion microreactors

This study introduces a Janus colloid surfactant catalyst platform exhibiting remarkable catalytic activity and magnetic responsiveness in Pickering emulsion microreactors. The patching of catalytic nanoparticles (NPs) such as Pd NPs and Ag NPs on amphiphilic Janus microparticles (JMPs) permits the control of catalytic activity for the organic reactions occurring in emulsion droplets. Through model organic reactions including oxidation, amination, and reduction, we show that the JMP catalysts assemble at the reactantwater interface of Pickering emulsions and play an essential role in enhancing the reaction kinetics and product yields. Moreover, when Fe2O3 NPs were co-patched site specifically, the Pickering emulsion droplets showed magnetic responsiveness, thus leading to facile recovery of products and effective recycling of JMP catalysts. The colloid surfactant catalysts developed in our study are expected to advance the environment-friendly catalyst system for green chemistry.