Charge transfer modulation in layer-by-layer-assembled multilayered photoanodes for solar water oxidation

Recent years have witnessed a rise in the construction of transition metal chalcogenide (TMS)-based heterostructured photocatalysts in terms of their excellent light absorption and suitable energy level alignment. Nevertheless, controllable modulation of photoinduced charge separation/transfer towar...

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Bibliographic Details
Published in:Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2019, Vol.7 (39), p.22487-22499
Main Authors: Hou, Shuo, Dai, Xiao-Cheng, Li, Yu-Bing, Huang, Ming-Hui, Li, Tao, Wei, Zhi-Quan, He, Yunhui, Xiao, Guangcan, Xiao, Fang-Xing
Format: Article
Language:English
Subjects:
Assembly
Catalysis
Channels
Charge transfer
Construction
Current carriers
Electromagnetic absorption
Energy conversion
Energy levels
Flow channels
Heterostructures
Irradiation
Light irradiation
Modulation
Oxidation
Photoanodes
Photocatalysis
Photocatalysts
Photoredox catalysis
Polyethyleneimine
Quantum dots
Separation
Solar energy
Solar energy conversion
Tellurium
Titanium dioxide
Transition metal compounds
Water splitting
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Summary:Recent years have witnessed a rise in the construction of transition metal chalcogenide (TMS)-based heterostructured photocatalysts in terms of their excellent light absorption and suitable energy level alignment. Nevertheless, controllable modulation of photoinduced charge separation/transfer toward target active sites for photoredox catalysis still constitutes an enduringly challenging issue. Herein, tailor-made negatively charged mercaptoacetic acid (MAA)-capped CdX@MAA (X = Se, Te, S) quantum dot (QD) and positively charged ultra-thin branched poly-ethyleneimine (BPEI) layer building blocks were alternately assembled on the hierarchically ordered TiO 2 nanotube array (NP-TNTA) framework for general electrostatic layer-by-layer (LbL) assembly of spatially multilayered NP-TNTAs/(BPEI/CdX QDs) n (X = Se, Te, S) photoanodes. The ultra-thin BPEI polymer layer integrated in-between the interface of CdX QDs functions as a cascade hole transfer channel for efficiently extracting the holes photoexcited over neighboring CdX QD layers, and simultaneously, alternately deposited CdX QD layers serve as an efficacious photosensitizer for constructing directional electron flow channels. The unique integration mode and intimate interfacial interaction endowed by LbL assembly render the well-defined NP-TNTAs/(BPEI/CdX QDs) n multilayered heterostructures a high-efficiency photoanode toward photoelectrochemical (PEC) water splitting under both simulated solar and visible light irradiation, greatly outperforming the single and binary counterparts on account of in situ generation of two spatially separated charge transfer channels, ultimately synergistically boosting the separation efficiency and prolonging the lifetime of charge carriers. Our work would open up new frontiers for strategically mediating the interfacial charge transfer and advancing rational construction of heterostructured photocatalysts for solar energy conversion. Two spatially separated charge transfer channels were constructed in multilayered photoanodes for efficient solar water oxidation under both simulated and visible light irradiation.
ISSN:2050-7488
2050-7496
DOI:10.1039/c9ta08107k