Effect of MgO Surface Modification on the TiO2 Nanowires Electrode for Self-Powered UV Photodetectors

TiO2-based core shell structure has gained enormous significance and has developed as a promising candidate in photoelectrochemical (PEC) devices due to its excellent properties. Despite studies, the surface/interface chemistry in these nanostructures has not been fully understood and there is still much room to further improve the performance of related PEC devices. Here, using a closely integrated experimental investigation and mechanism analysis, we scrutinized the intrinsic role of the MgO coating in the photocurrent enhancement of TiO2@MgO core-shell structured UVPDs. We evidenced that after coating with MgO, the photocurrent of UVPDs has been significantly enhanced and the optimal coating time was found to be 45 min. A large responsivity of 365 mA W-1 at 360 nm and a simultaneously excellent on/off ratio of 16 739 are achieved, which have rarely reported previously. In addition, the structure-property relationships are well established in all studied UVPDs through comparing investigations. The superior performance is postulated to be strongly correlated to the suppression of the recombination of photogenerated electron with I-3(-) in electrolyte. This work sheds some light on searching for new structures for next-generation low cost, large area, and energy-efficient optoelectronic devices.