Noble Metals Can Have Different Effects on Photocatalysis Over Metal–Organic Frameworks (MOFs): A Case Study on M/NH2-MIL-125(Ti) (M=Pt and Au)

Authors

  • Dengrong Sun,

    1. Research Institute of Photocatalysis, State Key Laboratory of Photocatalysis on Energy and Environment, Fuzhou University, Fuzhou, 350002 (P.R. China)
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  • Wenjun Liu,

    1. Research Institute of Photocatalysis, State Key Laboratory of Photocatalysis on Energy and Environment, Fuzhou University, Fuzhou, 350002 (P.R. China)
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  • Dr. Yanghe Fu,

    1. Research Institute of Photocatalysis, State Key Laboratory of Photocatalysis on Energy and Environment, Fuzhou University, Fuzhou, 350002 (P.R. China)
    2. Current affiliation: Institute of Physical Chemistry, Zhejiang Normal University, Jinhua, 321004 (P.R. China)
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  • Zhenxing Fang,

    1. College of Chemistry, Fuzhou University, Fuzhou 350002 (P.R. China)
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  • Fangxiang Sun,

    1. Research Institute of Photocatalysis, State Key Laboratory of Photocatalysis on Energy and Environment, Fuzhou University, Fuzhou, 350002 (P.R. China)
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  • Prof. Dr. Xianzhi Fu,

    1. Research Institute of Photocatalysis, State Key Laboratory of Photocatalysis on Energy and Environment, Fuzhou University, Fuzhou, 350002 (P.R. China)
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  • Prof. Dr. Yongfan Zhang,

    Corresponding author
    1. College of Chemistry, Fuzhou University, Fuzhou 350002 (P.R. China)
    2. Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, Xiamen, 361005 (P.R. China)
    • Yongfan Zhang, College of Chemistry, Fuzhou University, Fuzhou 350002 (P.R. China)

      Zhaohui Li, Research Institute of Photocatalysis, State Key Laboratory of Photocatalysis on Energy and Environment, Fuzhou University, Fuzhou, 350002 (P.R. China)

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  • Prof. Dr. Zhaohui Li

    Corresponding author
    1. Research Institute of Photocatalysis, State Key Laboratory of Photocatalysis on Energy and Environment, Fuzhou University, Fuzhou, 350002 (P.R. China)
    2. College of Chemistry, Fuzhou University, Fuzhou 350002 (P.R. China)
    • Yongfan Zhang, College of Chemistry, Fuzhou University, Fuzhou 350002 (P.R. China)

      Zhaohui Li, Research Institute of Photocatalysis, State Key Laboratory of Photocatalysis on Energy and Environment, Fuzhou University, Fuzhou, 350002 (P.R. China)

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Abstract

M-doped NH2-MIL-125(Ti) (M=Pt and Au) were prepared by using the wetness impregnation method followed by a treatment with H2 flow. The resultant samples were characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray absorption fine structure (XAFS) analyses, N2-sorption BET surface area, and UV/Vis diffuse reflectance spectroscopy (DRS). The photocatalytic reaction carried out in saturated CO2 with triethanolamine (TEOA) as sacrificial agent under visible-light irradiations showed that the noble metal-doping on NH2-MIL-125(Ti) promoted the photocatalytic hydrogen evolution. Unlike that over pure NH2-MIL-125(Ti), in which only formate was produced, both hydrogen and formate were formed over Pt- and Au-loaded NH2-MIL-125(Ti). However, Pt and Au have different effects on the photocatalytic performance for formate production. Compared with pure NH2-MIL-125(Ti), Pt/NH2-MIL-125(Ti) showed an enhanced activity for photocatalytic formate formation, whereas Au has a negative effect on this reaction. To elucidate the origin of the different photocatalytic performance, electron spin resonance (ESR) analyses and density functional theory (DFT) calculations were carried out over M/NH2-MIL-125(Ti).The photocatalytic mechanisms over M/NH2-MIL-125(Ti) (M=Pt and Au) were proposed. For the first time, the hydrogen spillover from the noble metal Pt to the framework of NH2-MIL-125(Ti) and its promoting effect on the photocatalytic CO2 reduction is revealed. The elucidation of the mechanism on the photocatalysis over M/NH2-MIL-125(Ti) can provide some guidance in the development of new photocatalysts based on MOF materials. This study also demonstrates the potential of using noble metal-doped MOFs in photocatalytic reactions involving hydrogen as a reactant, like hydrogenation reactions.

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