Enhanced photoelectrochemical performance of carbon nanotubes-modified black TiO2 nanotube arrays for self-driven photodetectors

Abstract

Self-driven ultraviolet photodetectors based on wide-bandgap semiconductors have been well investigated but are still being explored for further performance enhancement. Here we report a self-driven electrochemical ultraviolet photodetector (EUVPD) using a three-dimensional nanostructured photoanode based on defect-engineered TiO 2 nanotube arrays (TNAs) modified with single-walled carbon nanotubes (SWCNTs) to enhance photoelectric performance. The EUVPDs based on Ar-annealed TNAs modified with 0.1 mg/mL of SWCNTs were found to have higher responsivity (∼60 mA/W), higher on/off current ratio (∼4.3 × 10 3 ), the faster response time (4 ms of rise-time and 27 ms of decay-time) when compared with unmodified and air-annealed ones. This performance enhancement is attributed to the highly efficient separation and transport of photoexcited carriers through the electrochemical redox reaction in the SWCNTs network anchored on the defect-engineered TNAs/electrolyte heterojunction nanostructure. • SWCNTs-modified TNAs were used to prepare the self-driven EUVPDs. • 3-D TNAs enabled an enhanced light-trapping effect inside the nanotubes. • TiO 2 /electrolyte heterojunction made a high-efficient separation of the electron-hole pairs. • SWCNTs anchored on 3-D TNAs enhanced the photoelectrochemical redox reaction.