Phương pháp solgel TiO2-CdS

PHƯƠNG PHÁP SOLGEL TiO2-CdS Nguyễn ĐằngTrai I. TẠO SOL TiO2/CdS  CdS: II-VI  TiO2: 3.21 eV to 3.4 eV  CdS : 2.42 eV  Các hóa chất cần thiết: ◦ Titanium (IV) isopropoxide. ◦ Cadmium acetate hydrate. ◦ Ethanol. ◦ H2S. ◦ HCl. Titanium (IV) isopropoxide  Ti[OCH(CH3)2]4  Colorless liquid  M = 284 g/mol  d = 0.937 g/cm3  Melting, boiling: 18–20 C, 232 C Cadmium acetate hydrate  (CH3CO2)2Cd . xH2O  (CH3CO2)2Cd . 2H2O ◦ White crystals ◦ M = 266.529 g/mol ◦ d = 2.01 g/cm3 ◦ Melting point: 130 C ◦ Soluble in water, ethanol. Ethanol  C2H5OH  Colourless liquid  M = 46.07 g/mol  d = 0.789 g/cm3  Melting, boiling: −114 C, 78 C Hydro sulfua  H2S (ít tan trong nước)  Colorless gas.  M = 34.082 g/mol  d = 1.363 g/l  Melting, boiling: -82.30 C, -60.28 C  Solubility in water: ◦ 0.4 g/100 ml (20 C) ◦ 0.25 g/100 ml (40 C)  Điều chế H2S: ◦ Không điều chế trong công nghiệp. ◦ HI+SO2H2O+H2S+I2 ◦ Trong phòng thí nghiệm: FeS + 2HCl  FeCl2 + H2S Titanium (IV) isopropoxide Ethanol (5ml : 25ml) Ethanol  Cadmium acetate (25ml : 0.5g) one drop of 0.5M HCl SOL TiO2/CdS Stir in an ice bath Mix in ice bathColorless Transparent saturated H2S water solution Add slowly Until: Yellow white Semi-transparent II.TẠO SOL CdS Colour: yellow to orange d = 4830 kg m-3 1. Cách 1:  Các hóa chất cần thiết: ◦ Polyethylene glycol (PEG) ◦ Cadmium nitrate (cung cấp Cd) ◦ Thiourea (cung cấp S) ◦ Ethanol ◦ Acetic Acid Polyethylene glycol  H(OCH2CH2)nOH Cadmium nitrate  Cd(NO3)2  White crystals  M = 236 g/mol  d = 3.60 g/cm3  Mp: 350 C Thiourea  SC(NH2)2  White solid  M = 76 g/mol  d = 1.405 g/ml  Mp: 182 C Ethanol  C2H5OH  Colourless liquid  M = 46.07 g/mol  d = 0.789 g/cm3  Melting, boiling: −114 C, 78 C Acetic acid  CH3COOH  Colourless liquid  M = 60 g/mol  d = 1.049 g/cm3  Mp, Bp: 16.5 C, 118.1 C Polyethylene glycol  Ethanol (0.6 ml  8.9 ml) Acetic Acid (0.5 ml) Stir Continue stir (1-hour) Cadmium nitrate (0.3 mol/l) Thiourea (0.3, 0.4 , 0.6 mol/l)  Ethanol Stir (1-hour) Add slowly SOL Stir (5-6 hours) 2. Cách 2:  Các hóa chất cần thiết: ◦ Cadmium acetate dihydrate (CAD) ◦ Thiourea (Tu) ◦ 1-Thioglycerol (TG) ◦ N,N-dimethylformamide (DMF) Cadmium acetate hydrate  (CH3CO2)2Cd . 2H2O ◦ White crystals ◦ M = 266.529 g/mol ◦ d = 2.01 g/cm3 ◦ Melting point: 130 C ◦ Soluble in water, ethanol. 1-thioglycerol  HSCH2CH(OH)CH2OH  M = 108 g/mol  d = 1.25 g/mL at 25 C Thiourea  SC(NH2)2  White solid  M = 76 g/mol  d = 1.405 g/ml  Mp: 182 C N,N-dimethylformamide  (CH3)2NC(O)H  Clear liquid  M = 73 g/mol  d = 0.944 g/cm3  Mp, Bp: -61 C, 153 C TG CAD Tu DMF Water (3:1 vol) CdS sol 20 mL 3. Cách 3:  Các hóa chất cần thiết: ◦ Cadmium nitride ◦ Ammonium thiocyanate ◦ n-Buthanol Cadmium nitride  Cd3N2  Black powder  M = 365 g/mol  3Cd(NH2)2(s) (180 C) → Cd3N2(s) + 4NH3(g) Ammonium thiocyanate  NH4SCN  Crystalline solid  M = 76 g/mol  d = 1.305 g/cm3  Mp, Bp: 149.5 C, 170 C n-Buthanol  C4H10O  Colourless liquid  M = 74 g/mol  d = 0.8098 g/cm3  Mp, Bp: −89.5 C, 117.7 C Khối lượng phân tử các chất  Cd: 112  S: 32  Ti: 48  O: 16  N: 14  H: 1  C: 12  CdS: 2.42 eV  TiO2: 3.21 eV to 3.4 eV Cadmium nitride 0.35 M n-Buthanol 50 ml  cadmium acetate dihydrate (CAD), thiourea (Tu), and 1-thioglycerol (TG) in 20 mL of N,N-dimethylformamide (DMF)/water (3:1, in volume) solvent.  The growth solution for the CdS film was composed by a mixture of cadmium nitride 0.35 M (98 %, Aldrich), ammonium thiocyanate 1.5 M (J.T. Baker) in 50 ml of n-buthanol. The growth solutions of the composite were prepared by amixture of the solutions used to grow CdS and TiO2, independently. The films were deposited on Corning glass using the Sol-Gel (Dip-Coating) method. The substrates were immersed in the growth solution with a velocity of 1.1 cm/min and taken away with the same velocity after 5 min. After the deposition, the films were dried at room temperature and were later thermally treated at 300 C during 30 min in argon flux and at atmospheric pressure  SEM, Micro-Raman, UV-Vis