Synthesis Of Selenium?Tellurium One-Dimensional Nanomaterials And Photoelectric Properties

One-dimensional selenium and tellurium nanomaterials are widely used in the fields of communications,chemical engineering,life sciences,etc.due to their unique and excellent photoelectric properties,but there is still a long way to go before the actual large-scale applications.First of all,in terms of the research on the growth mechanism of one-dimensional nanostructures,previous literatures have reported on the optimization on the synthesis methods of selenium nanowires,but there are relatively few studies on the growth mechanism of selenium nanowires from the perspective of thermodynamics.Secondly,the probability of success of these methods is relatively low,which will not be conducive to the application of selenium and tellurium semiconductor nanomaterials in photodetectors.In order to solve the aboved dilemma,we performed the following researchs:1.Study on the synthesis and growth mechanism of Se nanowires.In this work,selenourea(CH₄N₂Se)is used as the reducing agent and oxygen is used as the oxidant.The triangular selenium(t-Se)nanowires are successfully prepared by the liquid phase method at room temperature.The diameter of the as-prepared selenium nanowires is about 70-80 nm with growth direction along[001].We studied the thermodynamic growth mechanism of t-Se nanowires by controlling the aging time of amorphous Se colloids(2 min,5 min,20 min and 3 h).The results of aging time experiment indicated that the growth of t-Se nanowireswent through the process of amorphous selenium,spherical selenium colliods,and selenium nanowires,indicating that the growth mode of the selenium nanowires in the liquid conform to the"solid-liquid-solid".In addition,by agingthe amorphous selenium in a vacuum oven,we have studied the solid phase transformation process of amorphous selenium colloids.It is found that the formation of Se nanowires form Se colloids in the solid phase are as followed:firstly,seed crystals are formed on the surface of the selenium ball,and then the seed crystal would continuously consume the amorphous selenium to form t-Se nanowires.Interestingly,the growth process of the selenium nanowire also conforms to the"solid-liquid-solid"growth mechanism.2.The systhesis optimization of Te nanorods and research on the photoelectric properties of single Te nanorod.In this part,hexagonal phase tellurium nanowires and tellurium nanorods with diameters of 40 nm and 2.5?m are prepared by by solvothermal method using tellurium powder as raw material.The as-prepared one dimensional Te nanomaterials all growed along the[001]direction.To investigate the photoelectronic properties of single Te nanorod,we have successfully built single tellurium nanowire/rod photoelectric nanodevice by FIB-assisted method.We have further studied the photoelectric properties of single tellurium nanowire/rod photoelectric nanodevice.The results showed that the responsivity and gain of the single nanowire photodetector are 1.65x10⁴AW^-1and 5.0x10⁶%,respectively.The responsivity and gain of the single nanowire photodetector are 17 AW^-1and 5.4x10³%,respectively,and the?value is as high as 0.76,indicating that the single tellurium nanorod photodetector possesses better photoelectric conversion efficiency which cangreatly improve the light utilization rate.The aboved research lay a solid theoretical foundation for the practical applications of tellurium materials.3.Microwave-assisted synthesis of Cd Se nanomaterials.Cadmium selenide nanocrystals(Cd Se NCs)were successfully prepared using the microwave(MW)assisted method.The influence of different synthesis temperatures on the morphology and structure of Cd Se NCs were studied.The results show that no matter the reaction temperature is 150?or 180?,there are a small amount of nanowires with hexagonal phase structure in the as-prepared samples.In addition,the liquid phase method is used to load noble metals on the cadmium selenide nanosheets.The results show that obviousgold nanoparticles can be loaded on the cadmium selenide nanosheets without affecting the layered structure of the cadmium selenide nanosheets.