چكيده به لاتين
Nowadays, with increasing population and environmental issues caused by fossil fuel, hydrogen as a green fuel has attracted the researchers’ attention. One of the green methods of hydrogen production is the photocatalytic water splitting using titanium dioxide nanotubes array. Titanium dioxide as a photocatalyst has two deficiencies, one is the rapid recombination of electrons and holes, excited by light irradiation, and the second is a wide band gap. These problems reduce the rate of hydrogen evolution. In this study, titanium dioxide nanotubes array was synthesized by electrochemical anodic oxidation technique. Destabilization of the nanotubes array on the substrate due to its partial spalling both during anodizing and calcination was considered and attempts were made to increase its stability by controlling the amount of ammonium fluoride in the electrolyte, the potential difference applied, and the synthesis time. In order to obtain a regular nanotubes array, two-step synthesis method was used and nanotubes with the regular structure were prepared. In order to increase the hydrogen production rate, silver nitrate was doped on titanium dioxide nanotubes by two different methods including; doping during anodizing and doping in a chemical bath after anodizing. Due to the reduction of the titanium dioxide band gap and the reduced recombination of the electrons and holes by silver, the photocatalytic activity of the array was increased. The hydrogen production rate increased by 40% when doping was done during anodizing and by 23% when doping was performed in chemical bath after anodizing compared to the reference sample.
