Photocatalytic Synthesis of CdS(core)–CdSe(shell) Quantum Dots with a Heteroepitaxial Junction on TiO2: Photoelectrochemical Hydrogen Generation from Water. Issue 20 (28th August 2017)

• Record Type: Journal Article
• Authors: Kitazono, Kaoru; Akashi, Ryo; Fujiwara, Keigo; Akita, Atsunobu; Naya, Shin‐ichi; Fujishima, Musashi; Tada, Hiroaki
• Is Part Of: Chemphyschem. Volume 18:Issue 20(2017)
• Page Start: 2840
• Page End: 2845
• Publication Date: 2017-08-28
• Subjects: epitaxial junctions -- hydrogen evolution -- photoelectrochemical cell -- quantum dots -- water splitting; Chemistry, Physical and theoretical -- Periodicals; 541.05
• DOI: 10.1002/cphc.201700708
• Languages: English
• ISSNs: 1439-4235

Abstract

Abstract: A major challenge in chemistry for the synthesis of hetero‐nanostructures is to build up atomically commensurate interfaces for smooth interfacial charge transfer. Photodeposition of CdSe on a CdS‐preloaded mesoporous TiO2 nanocrystalline film yields CdS(core)–CdSe(shell) quantum dots (CdS@CdSe/mp‐TiO2 ) with a heteroepitaxial nanojunction at 298 K. Two‐electrode quantum‐dot‐sensitized photoelectrochemical (QD‐SPEC) cells with the structure photoanode |0.25 M Na2 S, 0.35 M Na2 SO3 (solvent=water)| cathode were fabricated. The CdS@CdSe QD‐SPEC cell affords a solar‐to‐current efficiency (STCE) of 0.03 % without external bias under illumination of simulated sunlight ( λ >430 nm, AM 1.5, one sun). By applying 0.1 V between the electrodes, the STCE increases up to 0.048 %, far surpassing the CdS/mp‐TiO2 and CdSe/mp‐TiO2 photoanode cells. The CdS–CdSe interfacial analysis by high‐resolution transmission electron microscopy and the band energy analysis taking the size quantization and the electrolyte effect indicate that the excellent performance of the CdS@CdSe/mp‐TiO2 photoanode originates from the effective charge separation due to the cascade‐like band edge alignment and the heteroepitaxial junction between CdS and CdSe QDs. In addition, high surface coverage of TiO2 with QDs can contribute to the reduction in the loss of the electron transport from TiO2 to the electron collecting electrode. Abstract : Catch the sun : Photodeposition of CdSe on a CdS‐preloaded mesoporous TiO2 nanocrystalline film yields CdS(core)–CdSe(shell) quantum dots (CdS@CdSe/mp‐TiO2 ) with a heteroepitaxial nanojunction at 298 K. Two‐electrode quantum‐dot‐sensitized photoelectrochemical (QD‐SPEC) cells were fabricated and demonstrated a solar‐to‐current efficiency of 0.03 % without external bias under simulated sunlight ( λ >430 nm, AM 1.5, one sun).