Deposition of CdS nanoparticles within free-standing both-side-open stretched TiO2 nanotube-array films for the enhancement of photoelectrochemical performance

A heterojunction CdS/TiO2 photoelectrode was prepared using pre-crystallized annealing, followed by solution-based methods, to deposit CdS within the tubes of a free-standing both-side-open TiO2 nanotube-array (TiNT) film. Such open-ended structures make the nanochannels more amenable to CdS deposition compared with close-ended structures, thus preventing entry clogging. In the experiment on photoelectrochemical (PEC) cells, the use of CdS/both-side-open TiNT film allows easy access of the outer light and the electrolyte to the nanochannels because of the uniform CdS deposition within the tubes. As compared to the one-side-close TiNT-based PEC cell, the maximum incident-photon-to-current conversion efficiency at 455 nm is increased from 41% to 68% in the both-side-open TiNT-based device measured at a potential of − 0.4 V versus Ag/AgCl under front-side illumination.

A free-standing both-side-open TiO2 nanotube-array (TiNT) film makes the nanochannels more amenable to CdS deposition compared with the close-ended structures, thus preventing entry clogging. The high-dispersive and uniform CdS deposition within the tubes allows easy access of the outer light and the electrolyte to the nanochannels, as well as provides superior electron-collection efficiency. This results in significant enhanced incident-photon-to-current conversion efficiency in the CdS/both-side-open TiNT compared with the CdS/one-side-close TiNT.Figure optionsDownload as PowerPoint slideHighlights
► A facile route to obtain a free-standing both-side-open stretched TiO2 nanotube-array film.
► Uniform CdS deposition within such both-side-open TiO2 nanotubes.
► The maximum incident-photon-to-current conversion efficiency is increased from 41% to 68%.