Photoelectrochemical performance of BiOI/TiO2 Nanotube Arrays (TNAs) p-n heterojunction synthesized by SILAR-ultrasonication-assisted methods

<p class="MsoNormal"><span>In order to extend the visible region activity of titania nanotube array (TNAs) films, the Successive Ionic Layer Adsorption and Reaction (SILAR)-ultrasonication-assisted method has been used to prepare BiOI-modified TiO₂ nanotube arrays (BiOI/TNAs). The band gap of BiOI/TNAs for all the variations reveals absorption in the visible absorption. The surface morphology of BiOI/TNAs is shown in the nanoplate, nanoflake, and nanosheet forms with a vertical orientation perpendicular to TiO₂. The crystalline structure of BiOI did not change the structure of the anatase TNAs, with the band gap energy of the BiOI/TNAs semiconductor in the visible region. The photocurrent density of the BiOI/TNAs extends to the visible-light range. BiOI/TNAs with 1 mM Bi and 1 mM KI on TNAs 40 V 1 h 50 V 30 min shows the optimum photocurrent density. A tandem dye-sensitized solar cell (DSSC)-photoelectrochemical (PEC) was used for hydrogen production in salty water. BiOI/TNAs optimum was used as the photoanode of the PEC cell. Solar to hydrogen conversion efficiency (STH) of tandem DSSC-PEC reaches 1.34% in salty water.</span></p>