Abstract:

Asemiconductor heterostructure of TiO₂/CdS/cobalt phosphate water oxidation catalyst (Co-Pi WOC) photoanode was fabricated by the successive ionic layer adsorption and reaction (SILAR) procedure and photoassisted electro-deposition. The structure, morphologys and magnetic properties of the resultant particles were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS). CdS and Co-Pi quantum dots loaded on to the TiO₂ nanofilm. The TiO₂/CdS/Co-Pi photoanode had an initial photocurrent of 1.3 mA·cm^-2 and a stable level of 0.5 mA·cm^-2. A relatively stable level was maintained under visible light irradiation in neutral solution, especially at the low bias voltage of 0 V (vs Ag/AgCl). In this system, CdS quantum dots serve as the light absorber and generate electron holes; the Co-Pi WOC acts as a hole transfer layer that can transfer the hole for water oxidation; and the TiO₂ is the electron conductor for efficient charge transfer to the cathode to actualize proton reduction.

Key words: Photocatalysis, Water oxidation, Successive ionic layer adsorption and reaction, Visible light, TiO₂/CdS/Co-Pi photoanode