CdSe Quantum Dots Supported on Sb₂S₃ Nanorods as S-Scheme Heterojunction Photoanode in Photoelectrochemical Cells

The narrow bandgap semiconductor Sb2S3 has been extensively utilized in solar cells for its impressive light absorption coefficient and carrier mobility. However, a large number of deep energy defects provide carrier recombination sites that limit its photoelectrochemical (PEC) performance. In this study, Sb2S3 nanorods (NRs) and CdSe quantum dots (QDs) were successfully prepared, and Sb2S3/CdSe-annealed quasi-one-dimensional heterojunction photoanodes with the S-scheme were constructed. The Sb2S3/CdSe-annealed composite photoelectrode achieves a 12 times increase in photocurrent density compared to the 0.4 mA cm–2 of the Sb2S3 photoelectrode. Overall, the synergistic effect of the [hk1]-oriented Sb2S3 NRs and the S-scheme heterojunction promotes carrier transport, achieving a spatial separation of photogenerated carriers and efficiently weakening the recombination of the electron–hole pair. This study provides a simple method for the low-cost development of Sb2S3 NRs with [hk1] orientation and an idea to enhance its development in the PEC water splitting direction.