Metal Organic Frameworks Based Materials for Heterogeneous Photocatalysis

Abstract

The increase in environmental pollution due to the excessive use of fossil fuels has prompted the development of alternative and sustainable energy sources. As an abundant and sustainable energy, solar energy represents the most attractive and promising clean energy source for replacing fossil fuels. Metal organic frameworks (MOFs) are easily constructed and can be tailored towards favorable photocatalytic properties in pollution degradation, organic transformations, CO₂ reduction and water splitting. In this review, we first summarize the different roles of MOF materials in the photoredox chemical systems. Then, the typical applications of MOF materials in heterogeneous photocatalysis are discussed in detail. Finally, the challenges and opportunities in this promising field are evaluated.

Keywords: heterogeneous photocatalysis; metal-organic framework; solar energy.

Figure 1

(a) UV/Vis spectra of (a) MIL-125(Ti) and (b) NH2-MIL-125(Ti). The inset shows the samples. (b) Proposed mechanism for the photocatalytic CO₂ reduction over NH2-MIL-125(Ti) under visible light irradiation. Reproduced with permission from Reference [33]. Copyright 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim (c) UV/Vis solid-state absorption spectra of H₂TCPP[AlOH]₂ and Zn_0.986(12)H₂TCPP[AlOH]₂. (d) The photocatalytic reaction using Zn_0.986(12)H₂TCPP[AlOH]₂. (i) Reaction involving Zn_0.986(12)H₂TCPP[AlOH]₂, methyl viologen, colloidal platinum, and sacrificial EDTA. (ii) Reaction involving Zn_0.986(12)H₂TCPP[AlOH]₂, colloidal platinum, and sacrificial EDTA. Reproduced with permission from Reference [36]. Copyright 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Figure 2

(a) Schematic illustration showing the synthesis of Pt@MIL-125/Au and the corresponding Pt/MIL-125/Au and MIL-125/Au analogues. (b) Typical TEM images of (a) Pt@MIL-125, (b) Pt/MIL-125, (c) Pt@MIL-125/Au, and (d) Pt/MIL-125/Au. Reproduced with permission from Reference [46]. Copyright 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Figure 3

(a) TEM of (a) MIL-125-NH2, (b) Ag₃PO₄ NPs, (c) Ag₃PO₄@NH₂-MIL-125, and (d) high magnification of the particle edge of Ag₃PO₄@NH₂-MIL-125. (b) Photocatalytic decompositions of MB with Ag₃PO₄, NH₂-MIL-125, Ag₃PO₄@NH₂-MIL-125 composites and commercial TiO₂ (P25) under visible-light irradiation. (c) Photocatalytic decompositions of RhB with Ag₃PO₄, NH₂-MIL-125, Ag₃PO₄@NH₂-MIL-125 composites and commercial TiO2 (P25) under visible-light irradiation. Reproduced with permission from Reference [69]. Copyright 2017 Elsevier B.V. (d) The degradation efficiency (C_t/C₀) of PBS in presence of Pristine HKUST-1, Ag₃PO₄/HKUST-1 and Ag/Ag₃PO₄/HKUST-1. (e) Schematic diagram showing the band structure and Z-Scheme separation of photoinduced electron hole pairs at the interface of the Ag/Ag₃PO₄/HKUST-1 catalyst under visible light irradiation. (f) The repeated experiments of photocatalytic degradation of PBS over the Ag/Ag₃PO₄/HKUST-1 catalyst. Reproduced with permission from Reference [70]. Copyright 2017 Elsevier B.V.

Figure 4

(a) Schematic illustration of ZnO@N-NpC formation. (b) Photodegradation cures of MB as a function of UV irradiation time in the presence of catalysts commercial ZnO, ZIF-8, ZIF-8(700N) and ZnO@N-NpC(24 h). (c) The MB photocatalysis repeatability test. Reproduced with permission from Reference [77]. Copyright 2017 Elsevier Inc. (d) TEM images of (a) Fe₃O₄@HKUST-1 core–shell microspheres, (b) Fe₃O₄@CuO, (c and d) Fe₃O₄@C/Cu. (e) Photodegradation of different catalytic conditions under visible light irradiation. (f) Hysteresis loops recorded at 300 K of (a) Fe₃O₄@CuO, (b) Fe₃O₄@C/Cu and (c) the as-prepared Fe₃O₄@HKUST-1 (inset: separation of Fe₃O₄@CuO and Fe₃O₄@C/Cu from solution under an external magnetic field). Reproduced with permission from Reference [78]. Copyright 2013 Elsevier B.V.

Figure 5

(a) Proposed mechanism of energy transfer (EnT) in SO-PCN. (b) Illustration of switching operation in SO-PCN. (c) Photo-oxidation of DHN catalyzed by SO-PCN in the presence of oxygen and light irradiation. (d) UV/Vis spectra of photo-oxidation of DHN in CH₃CN catalyzed by SO-PCN. Inset: Absorbance of juglone (λ = 419 nm) as a function of reaction time. Reproduced with permission from Reference [89]. Copyright 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Figure 6

Photo-Oxygenation of Sulfides. Reproduced with permission from Reference [90]. Copyright 2014 American Chemical Society.

Figure 7

Light-induced catalytic performance for N-alkylation of amines with alcohols over Pd₁Au₁@MIL-100(Fe). Reproduced with permission from Reference [92]. Copyright 2018 Elsevier Inc.

Figure 8

Structures of Re_n-MOF and Ag⊂Re_n-MOF for plasmon-enhanced photocatalytic CO₂ conversion. (a) Zr₆O₄(OH)₄(−CO₂)₁₂ secondary building units are combined with BPDC and ReTC linkers to form Re_n-MOF. The structure of Re₃-MOF identified from single-crystal X-ray diffraction is shown. The 12 coordinated Zr-based metal clusters are interconnected by 21 BPDC and three ReTC linkers in a face-centered cubic array. Atom labeling scheme: C, black; O, red; Zr, blue polyhedra; Re, yellow; Cl, green; H atoms are omitted for clarity. (b) Re_n-MOF coated on an Ag nanocube for enhanced photocatalytic conversion of CO₂. Reproduced with permission from Reference [98]. Copyright 2016 American Chemical Society.

Figure 9

TEM images of ZnO@Co₃O₄ prepared from ZIF-8@ZIF-67: (a) before and (c) after photocatalytic CO₂ reduction. Schematic illustration of the photocatalytic CO₂ reduction with (b) ZnO@Co₃O₄. (d) CH₄ evolution over various samples under UV-vis irradiation. Reproduced with permission from Reference [100]. Copyright the Royal Society of Chemistry 2016.

Figure 10

(a) Schematic illustration showing the synthesis of Al-TCPP-Pt for photocatalytic hydrogen production. (b) Photocatalytic hydrogen production rates of Al-TCPP, Al-TCPP-PtNPs, and Al-TCPP-0.1Pt (inset: the calculated TOFs of Al-TCPP-PtNPs and Al-TCPP-0.1Pt). Reproduced with permission from Reference [105]. Copyright 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Figure 11

Schematic illustration of the electrostatic interaction assembly of ZnO/GO and Cu-BTC and its photocatalytic H₂ evolution mechanism. Reproduced with permission from Reference [74]. Copyright Tsinghua University Press and Springer-Verlag GmbH Germany 2017.