Refillable Fuel-Loading Microshell Motors for Persistent Motion in a Fuel-Free Environment

Artificial micro-/nanomotors that harvest environmental energy to move require energy surroundings; thus, their motion generally occurs in fuel solutions or under the real-time stimuli of external energy sources. Herein, inspired by vehicles, a refillable fuel-loading micromotor is proposed based on a 2 μm hemispherical multimetallic shell using catalase or platinum on its concave surface as the engine and the bowl structure as the fuel tank. H₂O₂ fuel is drawn into the microbowl by capillary action and restricted inside the bowl space through a self-generated O₂ bubble cap on the microshell mouth. The periodic growth and burst of the O₂ cap cause the enhanced diffusion motion of micromotors. This motion behavior can last for at least 30 min in a fuel-free environment with one H₂O₂ fueling. Additionally, the micromotor can be refilled repeatedly to achieve permanent motion. This demonstration of a refillable fuel-loading micromotor provides a model design of an energy built-in micromotor.