Dual-regulation charge separation strategy with the synergistic effect of 1D/0D heterostructure and inserted ferroelectric layer for boosting photoelectrochemical water oxidation

Abstract

The poor visible light utilization and inferior charge separation efficiency of the TiO₂ photoanode restrict its photoelectrochemical (PEC) activity for water oxidation. Therefore, herein, we report a dual-regulation charge separation strategy with a synergistic effect between a 1D/0D heterostructure and inserted ferroelectric layer in a TiO₂/SrTiO₃/CdS (nanorod/ferroelectric/quantum dot) composite photoanode to boost the PEC performance of TiO₂. The ferroelectric SrTiO₃ (STO) nanolayer exhibited a polar charge-induced electric field from the STO/CdS interface toward the TiO₂/STO interface, resulting from strong and endurable spontaneous polarization. The polar charge-induced electric field, assisted by the TiO₂/STO/CdS ternary heterojunction with cascade energy band alignment, simultaneously endowed persistent and rapid charge separation in the bulk and at TiO₂/STO/CdS interfaces, which enhanced the charge separation efficiency by 148% compared to that of pure TiO₂. Meanwhile, the obtained TiO₂/STO/CdS photoanode allowed the integration of boosted charge carrier density, easier hole extraction and increased active sites from the outer CdS 0D quantum dots. Consequently, the TiO₂/STO/CdS photoanode presented a prominently improved photocurrent of 1.85 mA cm⁻² (at 1.23 V vs. RHE), which was 7.4 times that of TiO₂. Thus, this integrated regulation strategy may open an avenue to pursue enhanced charge separation assisted by broadened light absorption for converting solar energy into fuel.