Phthalocyanine Dye-sensitized Tio <sub> 2 </ Sub> Photolysis Of Water Into Hydrogen Research

Hydrogen is considered as an ideal fuel for the future.The photocatalytic splitting of water to hydrogen using semiconductor as photocatalyst is an advanced method which has many advantages such as low-cost, environmentally friendly solar-hydrogen production to support the future hydrogen industry. Compared with other semiconductors, TiO₂ is much more promising as it is stable, non-corrosive, environmentally friendly and abundant. But its solar-to-hydrogen energy conversion efficiency is too low. But when TiO₂ is used as semiconductor for water-splitting to produce hydrogen, its solar-to-hydrogen energy conversion efficiency is too low because TiO₂ can not absord visble light which is the main part of sunlight, and it can only absord ultraviolet light which occupy merely 4% of sunlight that reach the earth's surface. In this paper, Pt/TiO₂ was prepared using homemade anatase TiO₂ and the photocataytic was prepared using phthalocyanine sensitization, then we succeed in using the photocataytic to produce hydrogen by water-splitting in visble light.This paper introduced the preparation of nano-TiO₂ with Sol-Gel method, which using ethanol as solvent, nitric acid as depressor, Ti(OBu)4 as raw material. The effective factors of Ti(OBu)4 concentration and gelatinization time were studied. The results showed that the best technologcial conditions were the mass ratio of Ti(OBu)4, H2O, nitric acid and ethanol was 8: 25: 3: 44, the churning time was 5h and the gelatinization time was 3d, with this understanding the average granularity of TiO₂ was below 10nm and particle size distribution was 5～40nm. Then prepared TiO₂ powder was characterized with X-ray diffraction (XRD) and Scanning Electron Microscope(SEM).The result showed that TiO₂ powder was Nano-sized and anatase crystal and the unit cell size was 9.9 nm.Pt/TiO₂ was prepared using homemade anatase TiO₂, and CuPc(SO₃Na)₄ was utilized as photosensitizer to prepare CuPc(SO₃Na)₄/Pt/TiO₂. Pt/TiO₂ and CuPc(SO₃Na)₄/Pt/TiO₂ were characterized with XPS, the result showed that Pt crystalline grain dispersed on TiO₂ surface exists as Pt0. Then Pt/TiO₂ and CuPc(SO₃Na)₄/Pt/TiO₂ were characterized with XRD and SEM.The result showed that Pt doping and dye sensitization had no effect on crystal structure of TiO₂.But the unit cell size of TiO₂ was enlarged to 17.3 nm after Pt doping and roasting,while the unit cell size of Pt/TiO₂ was nearly not changed after dye sensitization.TiO₂ and CuPc(SO₃Na)₄/Pt/TiO₂ were characterized with DRS, the result showed TiO₂ could absord light in range of 300～400nm in ultraviolet region but not in visible region, while CuPc(SO₃Na)₄/Pt/TiO₂ had an obvious absord in range of 600～700nm which showed that CuPc(SO₃Na)₄ could expand the absorption spectrum of TiO₂ to visible region. CuPc(SO₃Na)₄/Pt/TiO₂ was studied as photocatalyst for water-splitting to produce hydrogen under visible light irradiation. This paper also discussed the parameters of reaction that affect the production of hydrogen such as the amount of photocatalyst ,Pt doping,dye sensitization and the electron agent KI. The result showed that when the content of Pt doping, dye, KI and photocatalyst were 0.4%, 0.2%, 0.2 mol/L and 0.8 g/L, hydrogen evolution rate can reach the highest-level which was 1.4μmol/h.