Fig. 2
From: Free-standing millimetre-long Bi2Te3 sub-micron belts catalyzed by TiO2 nanoparticles
TiO2-catalyzed versus catalyst-free growth. SEM images of Bi2Te3 nanostructures from sample pairs from zones (I) and (II) with TiO2 catalyst nanoparticles (blue frame) and without catalyst (green frame). a Zone (I), TiO2: Platelets and belts grown with relatively high yield. Most platelets grow at an angle to the substrate normal. b Zone (I), catalyst-free: Only very few belts and almost no small platelets are grown. The most abundant structures are 10- μm-diameter platelets. c Zone (II), TiO2: Dense growth with significantly increased density of belts. d Zone (II), catalyst-free: The density of platelets increases compared to c. Some thin nanowires are observed