The photocatalytic activity and photostability of CdS quantum dot (QD) can be remarkably enhanced by hybridization with Rh-substituted layered titanate nanosheet even at very low Rh substitution rate (<1%). Mesoporous CdS-Ti(5.2-x)/6Rhx/2O2 nanohybrids are synthesized by a self-assembly of exfoliated Ti(5.2-x)/6Rhx/2O2 nanosheets with CdS QDs. The partial substitution of Rh3+/Rh4+ ions for Ti4+ ions in layered titanate is quite effective in enhancing an electronic coupling between hybridized CdS and titanate components via the formation of interband Rh 4d states. A crucial role of Rh substituent ion in the internal electron transfer is obviously evidenced from in situ X-ray absorption spectroscopy showing the elongation of (RhO) bond under visible light irradiation. This is the first spectroscopic evidence for the important role of substituent ion in the photoinduced electron transfer of hybrid-type photocatalyst. The CdS-Ti(5.2-x)/6Rhx/2O2 nanohybrids show much higher photocatalytic activity for H2 production and better photostability than do CdS and unsubstituted CdS-TiO2 nanohybrid. This result is ascribable to the enhancement of visible light absorptivity, the depression of electron-hole recombination, and the enhanced hole curing of CdS upon Rh substitution. The present study underscores that the hybridization with composition-controlled inorganic nanosheet provides a novel efficient methodology to optimize the photo-related functionalities of semiconductor nanocrystal.
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. NRF‐2014R1A2A1A10052809), by the National Research Foundation of Korea Grant funded by the Korean Government (MEST) (NRF‐2010‐C1AAA001‐2010‐0029065), and by the Cooperative Research Program for Agriculture Science & Technology Development (No. PJ01083001), Rural Development Administration, Republic of Korea. The experiments at PAL were supported in part by MOST and POSTECH. J. M. Lee acknowledges the Solvay Scholarship.
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All Science Journal Classification (ASJC) codes
- Materials Science(all)