Chinese Journal of Catalysis ›› 2022, Vol. 43 ›› Issue (2): 442-450.DOI: 10.1016/S1872-2067(21)63840-8

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Wheel-shaped icosanuclear Cu-containing polyoxometalate catalyst: Mechanistic and stability studies on light-driven hydrogen generation

Yeqin Feng, Lin Qin, Junhao Zhang, Fangyu Fu#(), Huijie Li, Hua Xiang, Hongjin Lv*()   

  1. MOE Key Laboratory of Cluster Science, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 102488, China
  • Received:2021-03-30 Accepted:2021-03-30 Online:2022-02-18 Published:2021-05-20
  • Contact: Fangyu Fu, Hongjin Lv
  • Supported by:
    This work was supported by the National Natural Science Foundation of China(21871025);This work was supported by the National Natural Science Foundation of China(21831001);This work was supported by the National Natural Science Foundation of China(22001016);the Recruitment Program of Global Experts (Young Talents);BIT Excellent Young Scholars Research Fund;the China Postdoctoral Science Foundation(2020TQ0038)

Abstract:

In this paper, we report the synthesis and characterization of a wheel-shaped icosanuclear Cu-containing polyoxometalate (POM), K12Li13[Cu20Cl(OH)24(H2O)12(P8W48O184)]·22H2O (K12Li13-Cu20P8W48). The resulting cation-exchanged tetrabutylammonium salt of the polyoxoanion Cu20P8W48 (TBA-Cu20P8W48) exhibits high efficiency for visible-light-driven H2 production in the presence of an [Ir(ppy)2(dtbbpy)][PF6] photosensitizer and a triethanolamine electron donor. Under optimal conditions, the turnover number for H2 production reaches ~2892 after 5 h of photocatalysis and thereafter continuously increases to ~13400 in a long-term 120 h reaction, representing the best performance among all reported transition-metal-substituted POM catalysts. Mechanistic studies confirm the existence of reductive and oxidative quenching processes, of which the reductive quenching pathway is dominant. Various stability tests demonstrate that the TBA-Cu20P8W48 catalyst slowly dissociates Cu ions under turnover conditions; however, both the starting TBA-Cu20P8W48 and its molecular decomposition products are dominant active species for efficient and long-term H2 production.

Key words: Polyoxometalates, Icosanuclear copper substitution, Light-driven hydrogen production, Photocatalytic mechanism, Stability study