Metal–organic frameworks as semiconductors

Silva, Cláudia G.; Corma, Avelino; Garcı́a, Hermenegildo

doi:10.1039/b924937k

Cited by 467 publications

(279 citation statements)

References 75 publications

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“…Interestingly, MOFs are also a class of potential semiconductors [257], which could be also directly applied in the photocatalytic CO 2 reduction as photocatalysts [258][259][260][261]. For example, Fu et al [259] reported that a photoactive Ti-containing metal-organic framework, NH 2 -MIL-125(Ti), exhibited a good photocatalytic activity for reduction of CO 2 to formate anion under visible light irradiation.…”

Section: Increased Surface Area For Co 2 Adsorptionmentioning

confidence: 99%

Design and fabrication of semiconductor photocatalyst for photocatalytic reduction of CO2 to solar fuel

et al. 2014

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The shortage of fossil fuels and the disastrous pollution of the environment have led to an increasing interest in artificial photosynthesis. The photocatalytic conversion of CO 2 into solar fuel is believed to be one of the best methods to overcome both the energy crisis and environmental problems. It is of significant importance to efficiently manage the surface reactions and the photo-generated charge carriers to maximize the activity and selectivity of semiconductor photocatalysts for photoconversion of CO 2 and H 2 O to solar fuel. To date, a variety of strategies have been developed to boost their photocatalytic activity and selectivity for CO 2 photoreduction. Based on the analysis of limited factors in improving the photocatalytic efficiency and selectivity, this review attempts to summarize these strategies and their corresponding design principles, including increased visible-light excitation, promoted charge transfer and separation, enhanced adsorption and activation of CO 2 , accelerated CO 2 reduction kinetics and suppressed undesirable reaction. Furthermore, we not only provide a summary of the recent progress in the rational design and fabrication of highly active and selective photocatalysts for the photoreduction of CO 2 , but also offer some fundamental insights into designing highly efficient photocatalysts for water splitting or pollutant degradation. INTRODUCTIONThe shortage of the energy supply and the problem of disastrous environmental pollution have been recognized as two main challenges in the near future [1]. It is a better way to efficiently and inexpensively convert solar energy into chemical fuels by developing an artificial photosynthetic (APS) system because solar fuels are high density energy carriers with long-term storage capacity. The most important and challenging reactions in APS-the photocatalytic water splitting into H 2 and O 2 (water reduction and oxidation) [2][3][4] and photoreduction of CO 2 to solar fuel, such as CH 4 and CH 3 OH [5,6] have been extensively studied since the photocatalytic water splitting on TiO 2 electrodes was discovered by Honda and Fujishima in 1972 [7]. The photocatalytic reduction of CO 2 by means of solar energy has attracted growing attention in the recent years, which 1 State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China 2 College of Science, South China Agricultural University, Guangzhou 510642, China 3 Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia * Corresponding author (email: jiaguoyu@yahoo.com) is also believed to be one of the best methods to overcome both global warming and energy crisis [8]. However, it is also generally thought that photocatalytic CO 2 reduction is a more complex and difficult process than H 2 production due to preferential H 2 production and low selectivity for the carbon species produced [9,10]. The progress achieved in the photoreduction of CO 2 is still far behind that in wate...

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Section: Increased Surface Area For Co 2 Adsorptionmentioning

confidence: 99%

Design and fabrication of semiconductor photocatalyst for photocatalytic reduction of CO2 to solar fuel

et al. 2014

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“…2 Particular focus is placed on applications of these materials in gas storage and separation (such as hydrogen, methane or carbon dioxide), 3 but now functionalities of MOFs include those long associated with conventional inorganic solid materials 4 such as electronic, 5 magnetic, 6 multiferroic 7 and catalytic properties. 8 The attraction of MOFs lies in the scope for the 'design' of new materials by combination of a metal centre that has a particular coordination preference with an organic ligand of specific geometry and binding configuration to yield a network with some degree of predictability of both structural and chemical properties.…”

Section: Introductionmentioning

confidence: 99%

A time-resolved diffraction study of a window of stability in the synthesis of a copper carboxylate metal–organic framework

et al. 2011

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An in situ, time-resolved energy dispersive powder X-ray diffraction study of the solvothermal crystallisation of the copper(II) 4,4 0 ,4 00 -benzene-1,3,5-triyl-tris(benzoate) metal-organic framework MOF-14 shows how reaction conditions must be carefully chosen to allow successful preparation of the material, since on prolonged heating at $120 C the material irreversibly collapses into Cu 2 O under solvothermal conditions in less than 2 hours. This situation is in contrast to the related Cu(II)-containing metal-organic framework HKUST-1, which shows solvothermal stability over similar temperatures and reaction times. The kinetics of crystallisation of both MOFs are examined using a mathematical model proposed by Gualtieri for zeolite crystallisation: this allows separation of the nucleation and growth regimes to yield two rate constants. Arrhenius analysis gives activation energies that reveal in both cases the crystallisations are nucleation controlled. For MOF-14 we can additionally simulate its decomposition as dissolution of the first-formed interpenetrating structure: this produces a complete picture of the solvothermal stability of MOF-14 as nucleation-growth crystallisation, with some evidence of secondary nucleation, followed by dissolution.

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“…The intrinsic lack of affinity between the inorganic and organic phases causes the formation of non-selective voids that lead to signicant losses in selectivity. 33 Many solutions suggested to promote adhesion, such as using compatibilisers, 34,35 silylation, 36 priming 37,38 etc., have proven to be material-and time-intensive, and sometimes fail to enhance dispersion.magnetism, 41 semiconductors, 42 and drug delivery. 43 For gas separation, MOFs are very attractive owing to their tailorable chemistry, tunable composition, well-dened pore size, pore exibility, and breathing effects.…”

Section: 30mentioning

confidence: 99%

Mixed matrix membranes prepared from non-dried MOFs for CO₂/CH₄ separations

2016

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Mixed matrix membranes (MMMs) aim at combining the processibility of polymers with the molecular sieving of fillers to improve gas separation performance. Metal-organic frameworks (MOFs) are a new family of materials with promising potential as fillers. The first part of this work reports on exploiting the versatility of MOF synthesis routes by forming ZIF-8 particles in polymer solutions to subsequently cast membranes directly from the solution. Although MOFs can be synthesised in a polymer medium, the decline in the synthesis yield does not allow for high loading in the MMMs. The second part describes a method for preparing MMMs with the commercial polyimide (PI) Matrimid® and ZIF-8, ZIF-7 and NH 2 -MIL-53(Al) as non-dried filler with 30 wt% and 50 wt% loading. A comparison of this method with the conventional approach of drying MOFs prior to incorporation exhibits the flexibility MOFs provide in membrane synthesis, in contrast to e.g. zeolites which intrinsically have to be calcined to become useful. The membranes with non-dried MOFs show some improvement in performance as compared to the unfilled polymer-only membranes, while those with dried MOFs even lose the inherent selectivity of the polymer.

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Metal–organic frameworks as semiconductors

Cited by 467 publications

References 75 publications

Design and fabrication of semiconductor photocatalyst for photocatalytic reduction of CO2 to solar fuel

Design and fabrication of semiconductor photocatalyst for photocatalytic reduction of CO2 to solar fuel

A time-resolved diffraction study of a window of stability in the synthesis of a copper carboxylate metal–organic framework

Mixed matrix membranes prepared from non-dried MOFs for CO₂/CH₄ separations

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Metal–organic frameworks as semiconductors

Cited by 467 publications

References 75 publications

Design and fabrication of semiconductor photocatalyst for photocatalytic reduction of CO2 to solar fuel

Design and fabrication of semiconductor photocatalyst for photocatalytic reduction of CO2 to solar fuel

A time-resolved diffraction study of a window of stability in the synthesis of a copper carboxylate metal–organic framework

Mixed matrix membranes prepared from non-dried MOFs for CO2/CH4 separations

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Mixed matrix membranes prepared from non-dried MOFs for CO₂/CH₄ separations