Synthesis And Characterization Of Co-doped SnO₂ One-dimensional Nanostructures With Graded Diameters

Tin dioxide is typical semiconductor material with a wide bandgap of 3.6eV. The existence of surface oxygen defects or tin interstitial atoms and quantum size effects make its nanostructures very attractive in solar cells, gas sensors, and nano-optoelectronics. However, controllable growth of SnO2 1D nanostructures is still the most important problem that the researchers have to overcome. At the same time, tin dioxide as a substrate for gas sensor is highly welcome. Through metal-doping, we can improve sensor's performance. Therefore, the doped tin dioxide 1D nanomaterials are currently the research field of nanotechnology and an important research direction. In this paper, we mainly carry out experiments around tin dioxide 1D nanostructures'controlled growth and Co-doping.Currently, CVD method is a widely used method of fabrication, due to its low demand in equipment, simple operation and low cost. In this paper, firstly, through the control of materials'growth conditions (pressure, temperature of the source zone, flux of carrier gases, oxygen content, etc.), using tin and oxygen as source materials, and under the protection of argon gas, we have achieved controllable growth in diameters of tin dioxide ID nanostructures. Specifically, by controlling the oxygen content basically unchanged during the growth process, we find that the diameters of tin dioxide nanostructures are uniform distributed, but increase with increasing oxygen content; by periodic adjustment of oxygen content during the growth process, we have achieved controllable diameters in a single SnO2 ID nanostructure; keeping other conditions unchanged, and through the regulation of the temperature of the source area, we find materials along different radial tracks to grow, and this change may be attributed to the surface energy tending to the lowest. The growth mechanism of SnO2 1D nanostructures has also been discussed and analyzed.Secondly, based on the controlled growth of nanostructures, their potential applications are also been discussed. In order to provide a new insight into gas sensing, or a driving force to explore the future gas sensor, it's necessary to prepare some novel nanostructures by way of designing experiments, and then study their optical transmission or electric transport, and so on. Furthermore, we can broaden the application of nanomaterials. Finally, by means of mixing the raw materials, tin and cobalt powder, we successfully synthesized Co-doped tin dioxide 1D nanowires using chemical vapor deposition method. From the XRD spectra of tin dioxide nanowires, we can find that characteristic diffraction angles of the Co-doped ones are relatively right-shifting compared with the undoped one, meanwhile, the lattice constants of these nanomaterials have taken some changes with the Co concentration increasing, which may be attributed to that Co element truly enters into the crystal lattice of tin dioxide nanowires, resulting in subtle changes of the lattice constants.