Size‐Tailored ZnO Submicrometer Spheres: Bottom‐Up Construction, Size‐Related Optical Extinction, and Selective Aniline Trapping

Fabrication of size-tailored semiconductor/metal submicrometer spherical particles has recently attracted signifi cant interest due to their unique physicochemical properties and emerging applications in many strategically important fi elds such as photonic crystals, pharmaceuticals, electronics, catalysis, energy, and environmental protection. [ 1 ] ZnO, with a wide bandgap of 3.37 eV and a large exciton binding energy of 60 meV, is one of the key semiconductors, widely utilized in piezoelectric transducers, varistors, phosphors, sensors, solar cells, and transparent conducting fi lms. [ 2 ] Due to the intrinsic nature of polar hexagonal-phase ZnO with an a : c axial ratio of 1:1.6, diverse well-defi ned 1D nanostructures have been synthesized [ 3 ] and utilized in a variety of functional device applications, such as light-emitting diodes, nanolasers, photodetectors, fi eld-effect transistors, photovoltaic devices, nanogenerators, and chemical sensors. [ 4 ] Comparatively, the creation of spherical crystals of ZnO, which are thought to be an attractive material for photonic crystals, sensors, solar cells, and photocatalysts, has seldom been reported. [ 5 ] Furthermore, even within those few existing reports, the resultant submicrometer ZnO spherical particles have usually been built up by secondary structures, such as nanoparticles and nanoplates, [ 5 ] where the lack of close contact between nanostructures will inevitably infl uence and possibly reduce the performance of ZnO submicrometer spheres in electric, magnetic, optoelectric, and thermoelectric applications. Consequently, it remains a challenge to acquire ZnO submicrometer spheres constructed without subunits. However, the synthesis of such spherical semiconductor/metal particles has been rarely reported. One effective approach has