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•Fe(III)-based MOF was firstly applied to the photocatalytic reduction reaction.•MIL-53(Fe) exhibited an outstanding photocatalytic activity for reduction of Cr(VI).•A first ...systematic study of the Fe(III)-based MOF as bifunctional photocatalyst.•Dyes and Cr(VI) could be also converted simultaneously over MIL-53(Fe).•MIL-53(Fe) was performed a stable and reusable visible-light-driven photocatalyst.
A bifunctional photocatalyst-Fe-benzenedicarboxylate (MIL-53(Fe)) has been synthesized successfully via a facile solvothermal method. The resulting MIL-53(Fe) photocatalyst exhibited an excellent visible light (λ≥ 420nm) photocatalytic activity for the reduction of Cr(VI), the reduction rate have reached about 100% after 40min of visible light irradiation, which has been more efficient than that of N-doped TiO2 (85%) under identical experimental conditions. Further experimental results have revealed that the photocatalytic activity of MIL-53(Fe) for the reduction of Cr(VI) can be drastically affected by the pH value of the reaction solution, the hole scavenger and atmosphere. Moreover, MIL-53(Fe) has exhibited considerable photocatalytic activity in the mixed systems (Cr(VI)/dyes). After 6h of visible light illumination, the reduction ratio of Cr(VI) and the degradation ratio of dyes have been exceed 60% and 80%, respectively. More significantly, the synergistic effect can also be found during the process of photocatalytic treatment of Cr(VI) contained wastewater under the same photocatalytic reaction conditions, which makes it a potential candidate for environmental restoration. Finally, a possible reaction mechanism has also been investigated in detail.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Proper design and preparation of high-performance and stable dual functional photocatalytic materials remains a significant objective of research. In this work, highly dispersed Pd nanoparticles of ...about 3-6 nm in diameter are immobilized in the metal-organic framework (MOF) UiO-66(NH₂) via a facile one-pot hydrothermal method. The resulting Pd@UiO-66(NH₂) nanocomposite exhibits an excellent reusable and higher visible light photocatalytic activity for reducing Cr(vi) compared with UiO-66(NH₂) owing to the high dispersion of Pd nanoparticles and their close contact with the matrix, which lead to the enhanced light harvesting and more efficient separation of photogenerated electron-hole pairs. More significantly, the Pd@UiO-66(NH₂) could be used for simultaneous photocatalytic degradation of organic pollutants, like methyl orange (MO) and methylene blue (MB), and reduction of Cr(vi) with even further enhanced activity in the binary system, which could be attributed to the synergetic effect between photocatalytic oxidation and reduction by individually consuming photogenerated holes and electrons. This work represents the first example of using the MOFs-based materials as dual functional photocatalyst to remove different categories of pollutants simultaneously. Our finding not only proves great potential for the design and application of MOFs-based materials but also might bring light to new opportunities in the development of new high-performance photocatalysts.
Metal-organic frameworks (MOFs) have been arousing a great interest owing to their unique physicochemical properties. In this work, Zr-benzenedicarboxylate (UiO-66) and its derivative, ...Zr-2-NH2-benzenedicarboxylate (UiO-66(NH2)), are successfully prepared via a facile solvothermal method and applied to photocatalytic reactions. Powder X-ray diffraction (XRD) confirms the isoreticular nature of UiO-66 and UiO-66(NH2), while Fourier transformed infrared spectra (FTIR) prove the effective presence of amino group. UV-vis diffuse reflectance spectra (DRS) show the photoabsorption edge of UiO-66 could be shifted to the visible light region by simply introducing the amino group (-NH2) on the organic ligand. Importantly, UiO-66(NH2) is proved to perform as an efficient multifunctional visible-light-driven photocatalyst with high stability and considerable recyclability in both the photocatalytic selective oxidation of alcohols to aldehydes using molecular oxygen as oxidant and catalytic reduction of aqueous Cr(VI) to Cr(III) under ambient conditions. Furthermore, the possible reaction mechanism has also been investigated in detail. This work makes a systematic attempt to understand the reaction of photocatalytic selective oxidation of alcohols over MOFs and represents the first example to report the identification of MOFs as promising visible-light photocatalysts toward reduction of aqueous Cr(VI). More significantly, our finding also provides a new way to design MOFs-based photocatalysts, that is, by tuning the predesigned ligands with specific functional groups, the optical absorption properties of MOFs can be flexibly modulated, and then the effective solar energy conversion can be expected.
UiO-66-X (X = H, NH2, NO2, Br) have been successfully synthesized and tested for their photocatalytic activity in water treatment. Results show that electronic effect of the ligand substituents ...greatly affects the photocatalytic activity of UiO-66. The rates obtained by different substituents are linearly correlated with their Hammett coefficients.
In this work, MIL-53(Fe)-reduced graphene oxide (M53-RGO) nanocomposites have been successfully fabricated by a facile and efficient electrostatic self-assembly strategy for improving the ...interfacial contact between RGO and the MIL-53(Fe). Compared with D-M53-RGO (direct synthesis of MIL-53(Fe)-reduced graphene oxide nanocomposites via one-pot solvothermal approach), M53-RGO nanocomposites exhibit improved photocatalytic activity compared with the D-M53-RGO under identical experimental conditions. After 80 min of visible light illumination (λ ≥ 420 nm), the reduction ratio of Cr(VI) is rapidly increased to 100%, which is also higher than that of reference sample (N-doped TiO2). More significantly, the M53-RGO nanocomposites are proven to perform as bifunctional photocatalysts with considerable activity in the mixed systems (Cr(VI)/dyes) under visible light, which made it a potential candidate for industrial wastewater treatment. Combining with photoelectrochemical analyses, it could be revealed that the introduction of RGO would minimize the recombination of photogenerated electron–hole pairs. Additionally, the effective interfacial contact between MIL-53(Fe) and RGO surface would further accelerate the transfer of photogenerated electrons, leading to the enhancement of photocatalytic activity of M53-RGO toward photocatalytic reactions. Finally, a possible photocatalytic reaction mechanism is also investigated in detail.
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IJS, KILJ, NUK, PNG, UL, UM
Proper design and preparation of high-performance and stable dual functional photocatalytic materials remains a significant objective of research. In this work, highly dispersed noble-metal ...nanoparticles (Au, Pd, Pt) were immobilized on MIL-100(Fe) (denoted M@MIL-100(Fe)) using a facile room-temperature photodeposition technique. The resulting M@MIL-100(Fe) (M = Au, Pd, and Pt) nanocomposites exhibited enhanced photoactivities toward photocatalytic degradation of methyl orange (MO) and reduction of heavy-metal Cr(VI) ions under visible-light irradiation (λ ≥ 420 nm) compared with blank-MIL-100(Fe). Combining these results with photoelectrochemical analyses revealed that noble-metal deposition can effectively improve the charge-separation efficiency of MIL-100(Fe) under visible-light irradiation. This phenomenon in turn leads to the enhancement of visible-light-driven photoactivity of M@MIL-100(Fe) toward photocatalytic redox reactions. In particular, the Pt@MIL-100(Fe) with an average Pt particle size of 2 nm exhibited remarkably enhanced photoactivities compared with those of M@MIL-100(Fe) (M = Au and Pd), which can be attributed to the integrative effect of the enhanced light absorption intensity and more efficient separation of the photogenerated charge carrier. In addition, possible photocatalytic reaction mechanisms are also proposed.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
CdS nanorods have been successfully decorated on the surface of MOF (metal-organic framework) UiO-66(NH sub(2)) viaa facile room-temperature photodeposition technique in a controlled manner. ...Electrochemical measurements indicate that the CdS photodeposition proceeds viathe preferential reduction of Cd ions to Cd super(0) followed by chemical reaction with S sub(8). The photocatalytic performances of the obtained CdS-UiO-66(NH sub(2)) nanocomposites have been evaluated by selective oxidation of various alcohol substrates using molecular oxygen as a benign oxidant. The results show that such CdS-UiO-66(NH sub(2)) nanocomposites exhibit considerable photocatalytic activity and stability, which may be due to the large specific surface area and the charge injection from CdS into UiO-66(NH sub(2)) leads to efficient and longer charge separation by reducing the recombination of electron-hole pairs. This work represents the first example of using MOFs not only as supports but also as electron providers to trigger the reaction for coupling MOFs with metal sulfides, thus fabricating novel MOF-CdS nanocomposite systems and improving their photocatalytic activity. It is hoped that our findings could offer useful information and open a new window for the design of novel MOF-semiconductor nanocomposites as efficient visible light driven photocatalysts.
The recovery process is a key determinant of system resilience because it describes the capability of a system to restore its performance after a disruption. In this work, we construct recovery ...functions that satisfy the necessary conditions to model the performance of critical infrastructure systems over time, during periods of loss and restoration following a disruptive event. To characterize the responses by various systems, we estimate the parameters of those functions by using empirical data about major infrastructure disruptions, including their recovery processes. The validity of our procedure is then illustrated by applying data from the three major utility companies that served New Jersey in the aftermath of Hurricane Sandy. Models are selected via standard methods to compare those recovery processes. Our results indicate that the recovery functions proposed here can capture the sensitivity of a system response to key parameters, thereby supporting the design of a more resilient system.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
We report the first use of polymeric carbon nitride (CN) for the catalytic selective oxidation of H
S. The as-prepared CN with unique ultrathin "nanomeshes" structure exhibits excellent H
S ...conversion and high S selectivity. In particular, the CN nanomesh also displays better durability in the desulfurization reaction than traditional catalysts, such as carbon- and iron-based materials.
A Ternary composite UiO-66/CdS/1% reduced graphene oxide (RGO) was successfully prepared, with a photocatalytic hydrogen evolution rate 13.8 times as high as that of pure commercial CdS. It shows ...great advantages over the perfect composite photocatalyst-P25/CdS/1%RGO.
