Fig. 2From: Atomic Layer Deposition of Pt Nanoparticles for Microengine with Promoted Catalytic MotionOptical images of microtube arrays made from different bilayers: a SiO/SiO2 (5/20 nm), b Ti/SiO2 (20/10 nm), c Ti/Co (10/10 nm), and d SiO2/Ti (10/20 nm). e–h Corresponding SEM images demonstrate the distribution of Pt nanoparticles on the inner tube wallsBack to article page