Preparation And Properties Of Nano-Ag₂S And Ag₂S/TiO₂ NAs Heterostructure

With the improvement of living standards, human pursue of low-carbon, environmental friendly, green and clean lifestyle However, excessive use of fossil fuels, has led to energy depletion and environmental pollution problems. So, the development and use of new clean energy is not only solve energy and environmental issues fundamental way, and but also achieve "low-carbon, environmental protection, clean and green" the imperative road. Solar energy provides energy for the growth of all things in a unique way. Meanwhile, it is the best clean energy and inexhaustible.Ag2S is a n-type semiconductor material with direct band gap (Eg≈0.93eV), and has a high absorption coefficient and the characteristics of excellent light, heat, electricity and other aspects. It can be more effective absorption and utilization of solar energy. However, TiO2 is currently one of the more mature light anode materials. But the application of TiO2 is seriously limited because of its wide band gap (Eg≈3.2eV) and inefficient. Therefore, using narrow bandgap semiconductor material sensitized TiO2 NAs composite as photoanodes is an effective method for improving the efficiency of TiO2.The thesis is based on preparation and photocatalystic properties study of different morphologies of Ag2S, and AgS2/TiO2 NAs heterostructure.1. Using different experimental methods, we successfully synthesized zero-dimensional, one-dimensional and three-dimensional Ag2S nanostructures by controlling the sulfur source, concentration, order and other parameters. The worm-like Nano (three-dimensional) Ag2S show the best photocatalytic performance. The ω and ρ were 4.07M/gh and 6.89×1017cm-3, and the size d of 60～80nm and l is 0.4～0.8μm. However, simple Ag2S photoelectric conversion efficiency is only 0.22%2. AgNO3 and Na2S·9H2O aqueous solutions were used as precursors. Ag2S-sensitized TiO2 NAs heteroj unction were synthesized by the ultrasound-assisted SILAR method. The size and coverage of Ag2S nanoparticles on TiO2 NAs can be tuned by changing the repeated cycles (n) of SILAR process. When n=6, the best performance of the Ag2S/TiO2 NAs, which the Jsc is up to 2.30mA/cm2, and the η and ω are as high as 1.51%, and 25.40 g/m2·h, respectively. The size and coverage of Ag2S are 8～2nm and 8.27%, respectively. Overall, properties of Ag2S/TiO2 NAs composite structure depend on the size and coverage of Ag2S nanoparticles. Only suitable size and load, the composite structure achieves the better performance.