Bimetallic coatings synergistically enhance the speeds of photocatalytic TiO₂ micromotors

The design of powerful, more biocompatible microrobots calls for faster catalytic reactions. Here we demonstrate a two-fold increase in the speed of photocatalytic TiO₂-metal Janus micromotors via a Au/Ag bi-layered coating. Electrochemical measurements show that such a bimetallic coating is a better photocatalyst than either metal alone. Similarly, an additional sputtered Ag layer could also significantly increase the speed of Pt-PS or TiO₂-Pt micromotors, suggesting that applying bimetallic coatings is a generalizable strategy in the design of faster catalytic micromotors.