TiO₂ Photoanodes Sensitized with Bi₂Se₃ Nanoflowers for Visible–Near-Infrared Photoelectrochemical Water Splitting

Abstract

Semiconducting photoelectrodes emerge as an efficient platform for converting light energy into hydrogen by photoelectrochemical (PEC) water splitting. The present study reports the improvement in PEC performance using metal oxide photoelectrodes sensitized with a narrow-band-gap semiconductor Bi2Se3, which extends the light response beyond the visible region and generates and transports charge carriers. When Bi2Se3 nanoflowers (NFs) were incorporated into the TiO2 electrode, the extent of hydrogen production was found to be increased by an order of magnitude. The binary electrode TiO2/Bi2Se3 nanocomposite exhibited a decent photocurrent density of 1.76 mA cm–2 at 1.23 V, which is three times superior to that of pure Bi2Se3 NFs. Moreover, the binary TiO2/Bi2Se3 electrode delivers the highest solar-to-hydrogen conversion efficiency of 1.01% at 0.6 V and incident photon-to-current conversion efficiency of 10.5%. Furthermore, both Bi2Se3 and TiO2/Bi2Se3 electrodes show superior photostabilities for over 6 h. The enhanced PEC activity is attributable to the facile transportation of photoelectrons from Bi2Se3 to TiO2 electrodes, thereby minimizing the charge recombination.