Beyond platinum: bubble-propelled micromotors based on Ag and MnO2 catalysts.

Autonomous bubble-propelled catalytic micro- and nanomachines show great promise in the fields of biomedicine, environmental science, and natural resources. It is envisioned that thousands and millions of such micromachines will swarm and communicate with each other, performing desired actions. To date, mainly platinum catalyst surfaces have been used for the decomposition of a fuel, hydrogen peroxide, to oxygen bubbles. Here we propose Pt-free, low-cost inorganic catalysts for powering micromotors based on silver and manganese dioxide surfaces. Such Ag- and MnO2-based bubble-powered micromotors show fast motion even at very low concentrations of fuel, down to 0.1% of H2O2. These catalysts should enable unparalleled widespread use of such motors in real applications, as it will be possible to make them in large quantities at low cost.