TiO2 nanotubes sensitized with CdSe quantum dots for photoelectrochemical solar hydrogen and oxygen generation

ANA MARÍA DALCIN FORNARI; MARIA FERNANDA TORRESAN; RODRIGO A. IGLESIAS; SERGIO RIBEIRO TEIXEIRA; DANIEL WEIBEL

Recife

Workshop; 3rd International Workshop on Fundamentals of Light-Matter Interaction; 2014

The Optical Society

The production of clean and renewable hydrogen from solar energy is the one of the most promising technology. In this work, we report the synthesis and photoelectrochemical (PEC) studies of TiO2 nanotubes (NTs) sensitized with CdSe quantum dots (QDs) for future application as photoanode in hydrogen generation through solar energy by water splitting. TiO2 NTs array were prepared by anodization of 3 cm diameter Ti sheets in a solution electrolyte of ethylene glycol, 10 wt % distilled water and 0,5 wt % NH4F, for 2 h in a voltage of 20V. To measure the PEC properties, the amorphous TiO2 NTs prepared were annealed at 400 °C for 3h to obtain 100% anatase TiO2 NTs. The synthesis CdSe QDs was performed by "Hot Injection method". This reaction was carried out by mixing the precursors at 225 °C under a controlled atmosphere of N2 and constant stirring. The Cd precursor solution was prepared from CdO, 1-octadecene and myristic acid. Once the temperature at 225 °C was controlled, the Se precursor containing elemental Se, 1-octadecene and trioctylphosphine was added to Cd precursor. From this mixture were taken aliquots at time intervals of about 30s. Modification of TiO2 NTs with CdSe QDs was given by "dipping". Modified TiO2 NTs were set in front of a quartz window on Teflon home made PEC reactor. It was used Na2S and Na2SO3 as sacrificial reagents. As-fabricated photoanode exhibited photocurrent significantly higher than TiO2 NTs without modification. Also was observed significant photoresponse in TiO2 NTs sensitized with CdSe QDs. Hydrogen and Oxygen evolution were measured simultaneously with changes in PEC parameters. The results demonstrate the importance to control the energy band gap for charge separation improving, transport and hydrogen generation.