Nucleation−Dissolution−Recrystallization: A New Growth Mechanism for t-Selenium Nanotubes

We report a hydrothermal reaction to make t -selenium nanotubes, in the absence of a surfactant or polymer to direct nanoparticle growth, and without externally added forces (such as ultrasonic). A series of electron microscopy characterization results suggest that the growth of t -selenium nanotubes is governed by a nucleation−dissolution−recrystallization growth mechanism. In this mechanism, t -selenium nanoparticles were initially formed in the hydrothermal system, then the t -selenium nanoparticles started to dissolve into the solution and grow onto large nanoparticles of selenium, and spherelike microparticles were obtained. The spherelike microparticles then gradually dissolved to generate selenium atoms in the solution; these selenium atoms were renewedly transferred onto the surfaces of the spherelike microparticles and were recrystallized. Along with the dissolution−recrystallization process, the spherelike microparticles gradually evolved into novel groovelike nanostructures. The nanogrooves could grow along the circumferential direction and the tuber axis direction until all spherelike microparticles had been completely consumed, eventually growing into t -selenium nanotubes. Studies found that this growth mechanism is strongly affected by temperature and concentrations of NaOH. By adjusting temperature and concentrations of NaOH, t -selenium nanotubes, nanowires, microrods, porous microtubes, and polyhedrons can be synthesized, respectively.