Nanoscale Magnetic Stirring Bars for Heterogeneous Catalysis in Microscopic Systems

Nanometer‐sized magnetic stirring bars containing Pd nanoparticles (denoted as Fe 3 O 4 ‐NC‐PZS‐Pd) for heterogeneous catalysis in microscopic system were prepared through a facile two‐step process. In the hydrogenation of styrene, Fe 3 O 4 ‐NC‐PZS‐Pd showed an activity similar to that of the commercial Pd/C catalyst, but much better stability. In microscopic catalytic systems, Fe 3 O 4 ‐NC‐PZS‐Pd can effectively stir the reaction solution within microdrops to accelerate mass transfer, and displays far better catalytic activity than the commercial Pd/C for the hydrogenation of methylene blue in an array of microdroplets. These results suggested that the Fe 3 O 4 ‐NC‐PZS‐Pd could be used as nanoscale stirring bars in nanoreactors.