Covalent-organic framework based Z-scheme heterostructured noble-metal-free photocatalysts for visible-light-driven hydrogen evolution

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2020-02, Vol.8 (8), p.4334-434
• Main Authors: Zhang, Yang-Peng, Tang, Hong-Liang, Dong, Hong, Gao, Meng-Yao, Li, Chang-Cheng, Sun, Xiao-Jun, Wei, Jin-Zhi, Qu, Yang, Li, Zhi-Jun, Zhang, Feng-Ming
• Format: Article
• Language: English
• Subjects: Aluminum; Catalysts; Composite materials; Construction; Electrons; Evolution; Ferric oxide; Heterostructures; Hybrids; Hydrogen; Hydrogen evolution; Irradiation; Light irradiation; Noble metals; Photocatalysis; Photocatalysts; Separation
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/c9ta12870k

The construction of a Z-scheme heterostructured system is an effective way to improve the separation of photogenerated electrons-holes and the hydrogen evolution activity of photocatalysts. In this work, for the first time, we report a class of covalent-organic framework (COF) based Z-scheme heterostructured hybrids for efficient visible-light-driven photocatalytic hydrogen evolution. An excellent visible-light harvesting COF, TpPa-2-COF, was chosen to integrate with α-Fe 2 O 3 for the construction of Z-scheme hybrids. As a result, the α-Fe 2 O 3 /TpPa-2-COF (3 : 7) hybrid material shows an optimal hydrogen evolution rate of 3.77 mmol h −1 g −1 without the participation of any noble metal co-catalyst. This hydrogen evolution rate is about 53 times higher than that of the parent TpPa-2-COF under the same conditions and comparable to that with a Pt (2 wt%) co-catalyst. Further investigations confirm that the tight integration of α-Fe 2 O 3 and 2D COFs can effectively promote the transfer of photogenerated electrons from the CB of α-Fe 2 O 3 to the VB of COFs thus leading to an efficient separation of photogenerated charges of the COF and a greatly enhanced photoactivity. Considering the first report of the COF-based Z-scheme heterostructure as a noble-metal-free photocatalyst for efficient hydrogen evolution, this work may open a new pathway for the further design and synthesis of COF-based hybrid photocatalysts for efficient H 2 evolution. A COF-based Z-scheme heterostructure hybrids (α-Fe 2 O 3 /TpPa-2-COF) for noble-metal-free photocatalytic hydrogen evolution.