Zeta potential dependent Self-electrophoresis of Pt-coated Janus particles in hydrogen peroxide solutions

We provide experimental results to show that self-propulsion of Janus particles made by coating platinum on the hemisphere of dielectric particles in hydrogen peroxide solution is similar to selfelectrophoresis. By different surface treatments and measuring the motion of particles and their {\zeta}-potentials, we find that the speed and direction of motion are determined by the {\zeta}-potential in a given concentration of hydrogen peroxide solution. When sign of {\zeta}-potential is changed from negative to positive, the direction of motion reverses from toward non-catalytic side to catalytic side. We also find that the angular distribution of Janus particle is more polarized with increasing of the concentration of hydrogen peroxide, which support the self-electrophoresis mechanism.