Fig. 4

Average speed of catalytic microengines decorated with Pt nanoparticles. a Average speeds of the four types of Pt nanoparticle-decorated microengines moving in 5 and 10 % H₂O₂ solutions, respectively. b The dependence of the average speed of microengines on the tube geometric parameter (X = 2 L/R) in a 5 % H₂O₂ aqueous solution. The red dashed line is from the theoretical prediction. The results from the experiment are demonstrated by colorized circles, and colorized squares represent the speeds after the surface areas are normalized