TiO2 spatially confined growth of Sb2(S,Se)3@TiO2 NT heterojunction photoanodes and their photoelectrochemical properties

Abstract

Titanium dioxide (TiO₂), a conventional n-type semiconductor, was widely used in photocatalysis, electrocatalysis and photoelectrocatalysis due to its good UV absorption and stable physical and chemical properties. However, its wide band gap and low oxygen reaction (OER) activity limited its application in photoelectrochemical (PEC) water splitting. In this work, we successfully constructed type-II Sb₂(S,Se)₃@TiO₂ core–shell heterojunctions. Antimony sulfide selenide (Sb₂(S,Se)₃) was a quasi-one-dimensional light-absorbing material with an adjustable band gap (1.1–1.8 eV), which broadened the TiO₂ light absorption range and effectively promoted the photogenerated carrier separation, transportation and utilization. Of particular note, novel Sb₂(S,Se)₃ nanospheres (NSPs) (ca. 69 nm) were in situ grown inside the tubes attributed to the unique space-confinement effect of TiO₂ nanotubes (NTs). The IPCE value for Sb₂(S,Se)₃@TiO₂ at 734 nm was 10.808% compared to 0.030% for TiO₂. The separation efficiency and injection efficiency increased from 2.48% and 31.62% to 4.90% and 36.48%, respectively. The onset potential was moved negatively by 60 mV, and the maximum photocurrent density of 1.53 mA cm⁻² at 1.23 V vs. RHE was 13.9 times higher than that of TiO₂ (0.11 mA cm⁻²). This work provided a new idea for the application of TiO₂ in the field of PEC water splitting.