Heterojunction of TiO2 nanotubes arrays/Bi2Se3 quantum dots as an effective and stable photoanode for photoelectrochemical H2 generation

Abstract

The use of semiconductor materials to split water through photoelectrochemical (PEC) processes is a remarkable technique that can transform solar energy into chemical energy, such as H2, in one step. For enhanced H2 generation, efficient separation of electron–hole (e−/h+) pairs and high photogenerated electron conductivity are required for photoanode substrates. In this study, an effective type II heterojunction between Bi2Se3 quantum dots (QDs) and TiO2 nanotube arrays (TNTAs) was constructed by depositing Bi2Se3 QDs on the TNTAs surface. The performance for PEC H2 generation was also investigated. The TNTAs/Bi2Se3 QDs demonstrated the highest photocurrent density of 1.75 mA cm−2, which is 3.8 times greater than bare TNTAs (0.46 mA cm−2) at 1.23 V vs. RHE. They also achieved a high hydrogen generation quantity of 355.8 μmol after 5 h, which is 3.3 times greater than bare TNTAs (105.3 μmol) at 1.23 V vs. RHE. TNTAs and TNTAs/Bi2Se3 QDs photoanodes both exhibited excellent stability for over 7 h. Compared with bare TNTAs, the TNTAs/Bi2Se3 QDs photoanode demonstrated a higher incident photon-to-current conversion efficiency (IPCE) in the UV region and expanded the light response to the visible region due to its lower charge recombination and larger visible light absorption. The exceptional performance of the TNTAs/Bi2Se3 QDs photoanode is due to its proper bandgap energy, which improves the visible light absorption, and its effective charge carrier transfer, which alleviates the recombination of e−/h+ pairs. The modification of TNTAs with Bi2Se3 QDs as a promising metal chalcogenide for improving visible light absorption and PEC water splitting performance has not yet been studied. Therefore, this work paves the way for a facile approach to construct a stable and high-performance photoanode for PEC H2 generation.