Heterostructured TiO2/MgO nanowire arrays for self-powered UV photodetectors

Heterostructured TiO2/MgO nanowire arrays (NWAs) were grown vertically on fluorine-doped tin oxide (FTO) glass by a simple solvothermal method. A photoelectrochemical self-powered UV photodetector (UVPD) was fabricated using the heterostructured TiO2/MgO nanowire arrays (NWAs) as the photoanode. The TiO2/MgO NWAs based UVPDs shows a higher photocurrent density (J) and open-circuit voltage (Voc) with respect to the UVPD with bare TiO2 NWAs under UV light irradiance. The intrinsic role of the MgO shell layer on the J and Voc varitions of UVPDs is investigated in detail. An impressive responsivity of 0.233 A W−1 was achieved for the UVPD with TiO2/MgO NWAs, which is the highest responsivity for photoelectrochemical self-powered UVPDs based on various TiO2 nanostructured photoanodes so far. Moreover, this UVPD also exhibits a high on/off ratio, fast response time, excellent visible-blind characteristic and linear optical signal response.