Electrodeposition Of Semiconductor Materials And Their Photoelectric Properties

Recently, due to the special physical and chemical properties and good performance in light absorption, semiconductor materials are more and more used in solar energy, especially in solar cells, splitting water, degrading organic pollutants and so on. Cul and Agl are both wide band gap semiconductors, and are widely applied in energy and solid ionic devices as superionic conductor. The excellent photocatalysis performance of Ag3PO4 has just been found. As a wide band gap semiconductor, TiO2, especially TiO2 nanotube arrays, are usually used as good photocatalyst. And now, more and more TiO2 nanotube arrays are doped and modified to improve their performance.Comparing with other preparation methods, electrodeposition has many advantages such as low temperature, low cost, controlling process and so on. Electrodeposition has been increasingly used in preparing high quality semiconductors. CuⅠ, AgⅠ, Ag3PO4 and TiO2/Ag3PO4 composite nanotube arrays are synthesized by electrodeposition, and their structures, morphologies and optical properties are studied in this thesis. The content and innovation of this thesis are listed as following:(1) PVP-assisted electrodeposition of Cul crystals:morphology evolution, phase transition, and optical properties. Cul has been prepared by electrodeposition before. It is well known that poly(N-vinylpyrrolidone) (PVP) is usually used as surfactant and stabilizer in preparing metals and their compounds. Different morphologies of Cul crystals are obtained by electrodeposition, and high-temperature metastable phase P-Cul crystals are also prepared. The amount ofβ-CuⅠincreases with the raise of PVP concentration.(2) Oriented AgⅠcrystals are obtained by electrodeposition at room temperature from the Ag(Ⅰ)-EDTA-Kl system. Additionally, the effect of potential is also studied in this thesis. At low applied potential, the obtained Agl crystals show hexagonal columnar shape. At higher potential, the obtained crystals show undefined morphology. The electrodeposited AgⅠcrystals were mixed withβ/γAgl phases and the composition of the mixture was determined by Rietveld method and the ratio of theβ/γphase was approximated 44/56. (3) Ag3PO4 crystals with well defined morphology are prepared by one step electrodeposition at room temperature. Ag+ are released from [Ag(NH3)2]+due to the acid produced through electrochemical method, and then Ag+ combines with PO43- to grow Ag3PO4 precipitate. In the experiments, the influence of applied potential and temperature of electrodeposition are discussed. The characterizations for the samples also prove that Ag3PO4 thin films prepared by electrodeposition have good performance in photocatalysis.(4) TiO2/Ag3PO4 composite nanotube arrays are obtained by electrochemical method and their photocatalysis performance are much better than TiO2 nanotube arrays. In the experiment, TiO2 nanotube arrays are synthesized by anodization assisted with ultrasound firstly. Then, Ag3PO4 crystals are electrodeposited into the TiO2 nanotube arrays assisted with ultrasound. The characterizations for the samples also prove that TiO2/Ag3PO4 composite nanotube arrays prepared by this method have excellent performance in photocatalysis.