Chinese Journal of Catalysis ›› 2022, Vol. 43 ›› Issue (8): 2249-2258.DOI: 10.1016/S1872-2067(22)64109-3

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Direct Z-scheme photochemical hybrid systems: Loading porphyrin-based metal-organic cages on graphitic-C3N4 to dramatically enhance photocatalytic hydrogen evolution

Yang Lei, Jian-Feng Huang, Xin-Ao Li, Chu-Ying Lv, Chao-Ping Hou, Jun-Min Liu()   

  1. The Key Laboratory of Low-Carbon Chemistry & Energy Conservation of Guangdong Province, School of Materials Science and Engineering, Sun Yat-sen University, Guangzhou 510275, Guangdong, China
  • Received:2022-02-23 Accepted:2022-04-15 Online:2022-08-18 Published:2022-06-20
  • Contact: Jun-Min Liu
  • Supported by:
    National Natural Science Foundation of China(21975291);National Natural Science Foundation of China(21572280);Natural Science Foundation of Guangdong Province(2019A1515011640);Natural Science Foundation of Guangdong Province(2022A1515011949);Natural Science Foundation of Guangdong Province(2020A1515110474);Natural Science Foundation of Guangdong Province(2018A030313479)

Abstract:

The rational design of photochemical molecular device (PMD) and its hybrid system has great potential in improving the activity of photocatalytic hydrogen production. A series of Pd6L3 type metal-organic cages, denoted as MOC-Py-M (M = H, Cu, and Zn), are designed for PMDs by combining metalloporphyrin-based ligands with catalytically active Pd2+ centers. These metal-organic cages (MOCs) are first successfully hybridized with graphitic carbon nitride (g-C3N4) to form direct Z-scheme heterogeneous MOC-Py-M/g-C3N4 (M = H, Cu, and Zn) photocatalysts via π-π interactions. Benefiting from its better light absorption ability, the MOC-Py-Zn/g-C3N4 catalyst exhibits high H2 production activity under visible light (10348 μmol g-1 h-1), far superior to MOC-Py-H/g-C3N4 and MOC-Py-Cu/g-C3N4. Moreover, the MOC-Py-Zn/g-C3N4 system obtains an enhanced turn over number (TON) value of 32616 within 100 h, outperforming the homogenous MOC-Py-Zn (TON of 507 within 100 h), which is one of the highest photochemical hybrid systems based on MOC for visible-light-driven hydrogen generation. This confirms the direct Z-scheme heterostructure can promote effective charge transfer, expand the visible light absorption region, and protect the cages from decomposition in MOC-Py-Zn/g-C3N4. This work presents a creative example that direct Z-scheme PMD-based systems for effective and persistent hydrogen generation from water under visible light are obtained by heterogenization approach using homogeneous porphyrin-based MOCs and g-C3N4 semiconductors.

Key words: Porphyrin-based metal-organic cage, g-C3N4, Photochemical molecular device, Direct Z-scheme heterostructure, Photocatalytic hydrogen evolution, from water