Self-Propelled Catalytic Particles with a Chemical Reaction

Abstract

Most catalytic micro/nanomotors that have been developed until now use hydrogen peroxide as fuel. The fuel is difficult to apply because they can cause skin irritation and often form disruptive bubbles. In this paper, we demonstrate a novel catalytic Pt micromotor that does not produce bubbles and is driven by the oxidation of stable and safe primary alcohols and aldehydes. We confirmed that primary alcohols and aldehydes are oxidized to aldehydes and carboxylic acids, respectively, using dissolved oxygen on the Pt surface. This use of organic oxidation mirrors living systems, and lends this new motor essentially the same characteristics, including decreased motility in low oxygen environments and the direct isothermal conversion of chemical energy into mechanical energy. In addition, the exerting power of the produced micromotor is roughly the same as that of a bacterium. These motors work even at fuel concentrations as low as 0.2 vol%, which is roughly equivalent to blood alcohol concentrations resulting from moderate drinking. Interestingly, motile direction is reversed by replacing the reducing fuels with oxidizers like hydrogen peroxide. Therefore, these micromotors not only provide a novel system in nanotechnology, but also help to further reveal the underlining mechanisms of the motion of smaller organisms.