A universal strategy boosting photoelectrochemical water oxidation by utilizing MXene nanosheets as hole transfer mediators

[Display omitted] •A novel interfacial charge modulation system for PEC water oxidation was designed.•MNs were utilized as hole transfer mediators between semiconductors and co-catalysts.•The ternary structure of the photoanodes could protect the MNs from oxidation.•Outstanding activity for PEC wate...

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Bibliographic Details
Published in:Applied catalysis. B, Environmental Environmental, 2021-11, Vol.297, p.120268, Article 120268
Main Authors: Yang, Gaoliang, Li, Sijie, Wang, Xusheng, Ding, Bing, Li, Yunxiang, Lin, Huiwen, Tang, Daiming, Ren, Xiaohui, Wang, Qi, Luo, Shunqin, Ye, Jinhua
Format: Article
Language:English
Subjects:
Catalysts
Charge transfer
Chemical evolution
Electric fields
Ferric oxide
Hole mobility
Hole transfer mediators
Interface modulation
MXene nanosheets
MXenes
Nanosheets
Oxidation
Photoelectric effect
Photoelectrocatalysis
Recombination
Zinc oxide
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Summary:[Display omitted] •A novel interfacial charge modulation system for PEC water oxidation was designed.•MNs were utilized as hole transfer mediators between semiconductors and co-catalysts.•The ternary structure of the photoanodes could protect the MNs from oxidation.•Outstanding activity for PEC water oxidation was achieved with optimized photoanodes.•The proposed strategy displayed the universality for efficient PEC water oxidation. As the rapid development of oxygen evolution catalysts (OECs) for photoanodes, the issue of charge transfer at the interface of OEC and semiconductor, which becomes the key challenge for the photoelectrochemical (PEC) efficiency, has been rarely addressed and should be taken seriously. Herein, a novel charge transfer system for PEC water oxidation is designed by inserting MXene nanosheets (MNs) between α-Fe2O3 and OEC. In this system, MNs act as the hole transfer mediators to efficiently suppress the interfacial charge recombination owing to the high hole mobility of MNs and the formation of built-in electric field at the MNs/α-Fe2O3 junction. Meanwhile, the OEC layers, in turn, can protect the MNs from oxidation to achieve prominent stability. The optimized photoanode of Co-Pi/MNs/α-Fe2O3 can achieve a remarkable photocurrent density, up to 3.20 mA cm−2 at 1.23 V vs. reversible hydrogen electrode (RHE) under AM 1.5 G illumination. An impressive cathodic onset potential shift of ∼250 mV is obtained on Co-Pi/MNs/α-Fe2O3 compared with the pristine α-Fe2O3. Furthermore, this strategy is also applicable to other photoanode materials, such as BiVO4, WO3 and ZnO, verifying the versatility by utilizing the MNs as hole transfer mediators for efficient photogenerated charge separation to enhance the PEC water oxidation.
ISSN:0926-3373
1873-3883
DOI:10.1016/j.apcatb.2021.120268