Research

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7 pages, 1076 KiB

Open AccessCommunication

Migration: A Neglected Potential Contribution of HCl-Oxidized Au(0)

by Zilong Zhang, Haifeng Zhang, Bolin Wang, Yuxue Yue and Jia Zhao

Molecules 2023, 28(4), 1600; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules28041600 - 07 Feb 2023

Cited by 4 | Viewed by 993

In this study, the typical oxidation process of Au/C catalysts exposed to HCl is presented. Although the process violates the standard electrode potentials, the “oxidized” tendency of Au(0) species is analyzed. This oxidation behavior can only be triggered over the Au/C sample within [...] Read more.

In this study, the typical oxidation process of Au/C catalysts exposed to HCl is presented. Although the process violates the standard electrode potentials, the “oxidized” tendency of Au(0) species is analyzed. This oxidation behavior can only be triggered over the Au/C sample within residual cationic Au species, and terminated over the completely metallic Au(0)/C sample. This study demonstrates that the presence of surface chlorination species cannot facilitate the oxidation of Au(0) and Au(I) when the sample is treated with HCl alone, which excludes the oxidation paths of: Au(0) → Au(III) and Au(I) → Au(III). The reported “HCl-oxidized Au(0)” behavior is partially caused by the migration of Au(III) species in the carbon bulk-phase, which occurs outside the XPS detection limit region and into the detection limit rather than the “HCl-oxidized Au(0)” itself. The mechanism of driving the bulk-phase Au(III) migrated from the steady destabilized state to the carbon surface is then studied. This study demonstrates that the migration of Au cannot be neglected behind the curious oxidation phenomenon by HCl, which provides a new perspective for the oxidation of other noble metals by HCl. Full article

(This article belongs to the Special Issue Functionalized Metal–Organic Frameworks for Sensing and Catalytic Application)

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16 pages, 3799 KiB

Open AccessArticle

Tuning Size and Properties of Zinc Ascorbate Metal-Organic Framework via Acid Modulation

by Tia Kristian Tajnšek, Nataša Zabukovec Logar and Matjaž Mazaj

Molecules 2023, 28(1), 253; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules28010253 - 28 Dec 2022

Cited by 1 | Viewed by 1594

Abstract

One of the biggest advantages of MOFs is the possibility of modifying their properties and tuning their inherent activity (i.e., sorption, storage, catalytic activity etc.). Textural properties can be tuned by manipulating process and compositional parameters, among which, the effect of additives can [...] Read more.

One of the biggest advantages of MOFs is the possibility of modifying their properties and tuning their inherent activity (i.e., sorption, storage, catalytic activity etc.). Textural properties can be tuned by manipulating process and compositional parameters, among which, the effect of additives can be even further distinguished among them based on the way they affect these properties. Beyond the effect that additives have on the size and morphology of nanoMOFs, there is also an effect on properties via creating point defects—missing linker and missing node defects. In this study, we investigated the effect of four monotopic acid modulators—formic, acetic, dichloroacetic and propionic acid, their concentration and the heating type (conventional and microwave—MW) on the size, morphology and textural properties of a recently discovered bioNICS1. It was confirmed that the proposed seesaw model for the controlled size of nanoMOF crystals is less applicable in the case of MW-assisted synthesis, in comparison to conventional heating. In the case of formic acid- and propionic acid-modified materials, we demonstrated that the type of additive plays a different role in crystal growth and generation of defects, implying high tunability being crucial for a material’s structure–property performance optimization. Full article

(This article belongs to the Special Issue Functionalized Metal–Organic Frameworks for Sensing and Catalytic Application)

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12 pages, 3292 KiB

Open AccessArticle

Filling Polyoxoanions into MIL-101(Fe) for Adsorption of Organic Pollutants with Facile and Complete Visible Light Photocatalytic Decomposition

by Qing Lan, Sujuan Jin, Bohan Yang, Zhiming Zhang, Xuyang Li, Haiquan Xie, Xiaoli Jin, Huan Zhang and Qiang Zhao

Molecules 2022, 27(11), 3404; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules27113404 - 25 May 2022

Cited by 10 | Viewed by 1977

Abstract

Transition metal-substituted polyoxometalates (POMs) were filled into a metal–organic framework (MOF) to construct a series of POM@MOF composites (PMo₁₂O₄₀@MIL-101, PMo₁₁VO₄₀@MIL-101, PMo₁₀V₂O₄₀@MIL-101). The composite materials possess ultra-high adsorption ability, especially [...] Read more.

Transition metal-substituted polyoxometalates (POMs) were filled into a metal–organic framework (MOF) to construct a series of POM@MOF composites (PMo₁₂O₄₀@MIL-101, PMo₁₁VO₄₀@MIL-101, PMo₁₀V₂O₄₀@MIL-101). The composite materials possess ultra-high adsorption ability, especially for PMo₁₀V₂O₄₀@MIL-101, with an adsorption capacity of 912.5 mg·g⁻¹ for cationic antibiotic tetracycline in wastewater, much higher than that of isolated MIL-101(Fe) and the commonly used adsorption materials, such as activated carbon and graphene oxide. In particular, they can be used as efficient photocatalysts for the photodegradation of antibiotics under visible light irradiation. The complete photodegradation of the adsorbed species can induce the facile reusability of these composites for multiple cycles. This work opens an avenue to introduce POMs into an MOF matrix for the simultaneous adsorption and photodegradation of antibiotics. Full article

(This article belongs to the Special Issue Functionalized Metal–Organic Frameworks for Sensing and Catalytic Application)

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9 pages, 4062 KiB

Open AccessArticle

Facile in Situ Transformation of NiOOH into MOF-74(Ni)/NiO OH Heterogeneous Composite for Enchancing Electrocatalytic Methanol Oxidation

by Wei-Qun Zhou, Ben-Jun Xi, Xi-Wen Chang, Bin Wang, Xue-Qian Wu, Shuang Li, Ya-Pan Wu and Dong-Sheng Li

Molecules 2022, 27(7), 2113; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules27072113 - 25 Mar 2022

Cited by 6 | Viewed by 2678

Abstract

A new MOF-74(Ni)/NiOOH heterogeneous composite was synthesized via NiOOH microsphere precursor. The electrocatalytic methanol oxidation reactions’ (MOR) performance was assessed. The as-prepared MOF-74(Ni)/NiOOH exhibited excellent activity with high peak current density (27.62 mA·cm⁻²) and high mass activity (243.8 mA·mg⁻¹). [...] Read more.

A new MOF-74(Ni)/NiOOH heterogeneous composite was synthesized via NiOOH microsphere precursor. The electrocatalytic methanol oxidation reactions’ (MOR) performance was assessed. The as-prepared MOF-74(Ni)/NiOOH exhibited excellent activity with high peak current density (27.62 mA·cm⁻²) and high mass activity (243.8 mA·mg⁻¹). The enhanced activity could be a result of the synergistic effect of the MOF-74(Ni)/NiOOH heterocomposite providing more exposed active sites, a beneficial diffusion path between the catalyst surface and electrolyte, and improved conductivity, favorable for improving MOR performance. Full article

(This article belongs to the Special Issue Functionalized Metal–Organic Frameworks for Sensing and Catalytic Application)

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13 pages, 2596 KiB

Open AccessArticle

Stable Zinc-Based Metal-Organic Framework Photocatalyst for Effective Visible-Light-Driven Hydrogen Production

by Li-Long Dang, Ting-Ting Zhang, Ting-Ting Li, Tian Chen, Ying Zhao, Chen-Chen Zhao and Lu-Fang Ma

Molecules 2022, 27(6), 1917; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules27061917 - 16 Mar 2022

Cited by 10 | Viewed by 2315

Abstract

Herein, a new Zn-MOF material, [Zn(L1)(L2)], 1, was built successfully through a one-pot solvothermal method. The 3D MOF structure was determined by Single X-ray diffraction analysis, IR, and elemental analysis. A series of PXRD tests of 1 after [...] Read more.

Herein, a new Zn-MOF material, [Zn(L1)(L2)], 1, was built successfully through a one-pot solvothermal method. The 3D MOF structure was determined by Single X-ray diffraction analysis, IR, and elemental analysis. A series of PXRD tests of 1 after being immersed in different solvents and pH solutions demonstrated the good stability of 1. Interestingly, this material displayed high catalytic activity for the visible-light-driven hydrogen generation under the illumination of white LED in pure water or a mixture of DMF and H₂O without additional photosensitizers and cocatalysts. Besides, the studies also showed that the catalytic activity changed constantly as well as the solvent ratio adjustment of DMF and H₂O from 4:6 to 2:8. Additionally, the catalytic activity reached the best value (743 μmol g⁻¹ h⁻¹) when the solvent ratio was 4:6. The heterogeneous nature and recyclability of the MOF catalyst, as well as several factors that affect the catalytic activity, were investigated and described in detail. Moreover, the photocatalytic mechanism for the hydrogen generation of 1 was also proposed based on the fluorescence spectra and UV-vis absorption. Full article

(This article belongs to the Special Issue Functionalized Metal–Organic Frameworks for Sensing and Catalytic Application)

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Review

Jump to: Research

17 pages, 5355 KiB

Open AccessReview

Tetrahedral Imidazolate Frameworks with Auxiliary Ligands (TIF-Ax): Synthetic Strategies and Applications

by Tong Hao, Hui-Zi Li, Fei Wang and Jian Zhang

Molecules 2023, 28(16), 6031; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules28166031 - 12 Aug 2023

Viewed by 786

Abstract

Zeolitic imidazolate frameworks (ZIFs) are an important subclass of metal–organic frameworks (MOFs). Recently, we reported a new kind of MOF, namely tetrahedral imidazolate frameworks with auxiliary ligands (TIF-Ax), by adding linear ligands (Hint) into the zinc–imidazolate system. Introducing linear ligands into the M [...] Read more.

Zeolitic imidazolate frameworks (ZIFs) are an important subclass of metal–organic frameworks (MOFs). Recently, we reported a new kind of MOF, namely tetrahedral imidazolate frameworks with auxiliary ligands (TIF-Ax), by adding linear ligands (Hint) into the zinc–imidazolate system. Introducing linear ligands into the M²⁺-imidazolate system overcomes the limitation of imidazole derivatives. Thanks to the synergistic effect of two different types of ligands, a series of new TIF-Ax with interesting topologies and a special pore environment has been reported, and they have attracted extensive attention in gas adsorption, separation, catalysis, heavy metal ion capture, and so on. In this review, we give a comprehensive overview of TIF-Ax, including their synthesis methods, structural diversity, and multi-field applications. Finally, we also discuss the challenges and perspectives of the rational design and syntheses of new TIF-Ax from the aspects of their composition, solvent, and template. This review provides deep insight into TIF-Ax and a reference for scholars with backgrounds of porous materials, gas separation, and catalysis. Full article

(This article belongs to the Special Issue Functionalized Metal–Organic Frameworks for Sensing and Catalytic Application)

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22 pages, 3178 KiB

Open AccessReview

Metal–Organic Frameworks for Electrocatalytic Sensing of Hydrogen Peroxide

by Shuhan Wang, Tong Zhang, Xukun Zhu, Shu Zu, Zexin Xie, Xiaoxiang Lu, Mingdao Zhang, Li Song and Yachao Jin

Molecules 2022, 27(14), 4571; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules27144571 - 18 Jul 2022

Cited by 16 | Viewed by 2846

Abstract

The electrochemical detection of hydrogen peroxide (H₂O₂) has become more and more important in industrial production, daily life, biological process, green energy chemistry, and other fields (especially for the detection of low concentration of H₂O_2). Metal [...] Read more.

The electrochemical detection of hydrogen peroxide (H₂O₂) has become more and more important in industrial production, daily life, biological process, green energy chemistry, and other fields (especially for the detection of low concentration of H₂O_2). Metal organic frameworks (MOFs) are promising candidates to replace the established H₂O₂ sensors based on precious metals or enzymes. This review summarizes recent advances in MOF-based H₂O₂ electrochemical sensors, including conductive MOFs, MOFs with chemical modifications, MOFs-composites, and MOF derivatives. Finally, the challenges and prospects for the optimization and design of H₂O₂ electrochemical sensors with ultra-low detection limit and long-life are presented. Full article

(This article belongs to the Special Issue Functionalized Metal–Organic Frameworks for Sensing and Catalytic Application)

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33 pages, 54462 KiB

Open AccessReview

Recent Progress in Metal-Organic Framework Based Fluorescent Sensors for Hazardous Materials Detection

by Dan Zhao, Shuang Yu, Wen-Jie Jiang, Zhi-Hao Cai, Dan-Li Li, Ya-Lan Liu and Zhi-Zhou Chen

Molecules 2022, 27(7), 2226; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules27072226 - 29 Mar 2022

Cited by 29 | Viewed by 4660

Abstract

Population growth and industrial development have exacerbated environmental pollution of both land and aquatic environments with toxic and harmful materials. Luminescence-based chemical sensors crafted for specific hazardous substances operate on host-guest interactions, leading to the detection of target molecules down to the nanomolar [...] Read more.

Population growth and industrial development have exacerbated environmental pollution of both land and aquatic environments with toxic and harmful materials. Luminescence-based chemical sensors crafted for specific hazardous substances operate on host-guest interactions, leading to the detection of target molecules down to the nanomolar range. Particularly, the luminescence-based sensors constructed on the basis of metal-organic frameworks (MOFs) are of increasing interest, as they can not only compensate for the shortcomings of traditional detection techniques, but also can provide more sensitive detection for analytes. Recent years have seen MOFs-based fluorescent sensors show outstanding advantages in the field of hazardous substance identification and detection. Here, we critically discuss the application of MOFs for the detection of a broad scope of hazardous substances, including hazardous gases, heavy metal ions, radioactive ions, antibiotics, pesticides, nitro-explosives, and some harmful solvents as well as luminous and sensing mechanisms of MOF-based fluorescent sensors. The outlook and several crucial issues of this area are also discussed, with the expectation that it may help arouse widespread attention on exploring fluorescent MOFs (LMOFs) in potential sensing applications. Full article

(This article belongs to the Special Issue Functionalized Metal–Organic Frameworks for Sensing and Catalytic Application)

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